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Groups > sci.electronics.design > #742648 > unrolled thread
| Started by | john larkin <jl@glen--canyon.com> |
|---|---|
| First post | 2026-04-02 13:56 -0700 |
| Last post | 2026-04-10 17:34 +0100 |
| Articles | 20 on this page of 63 — 7 participants |
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silly circuit john larkin <jl@glen--canyon.com> - 2026-04-02 13:56 -0700
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-03 16:45 +1100
Re: silly circuit piglet <erichpwagner@hotmail.com> - 2026-04-03 06:47 +0000
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-03 04:31 -0700
Re: silly circuit "Don" <g@crcomp.net> - 2026-04-08 15:51 +0000
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-03 08:20 -0700
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-04 03:10 +1100
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-03 09:29 -0700
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-04 04:48 +1100
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-03 14:07 -0700
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-04 17:33 +1100
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-04 03:59 -0700
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-05 00:35 +1100
Re: silly circuit someone <2a59d59e3809f827ce709d3815e3950eef4a6a93af5557a93a7fdfba71460843@example.com> - 2026-04-09 03:30 +0000
Re: silly circuit "Edward Rawde" <invalid@invalid.invalid> - 2026-04-03 13:27 -0400
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-04 17:22 +1100
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-04 18:07 -0700
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-05 12:24 +1000
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-04 19:37 -0700
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-05 14:14 +1000
Re: silly circuit "Edward Rawde" <invalid@invalid.invalid> - 2026-04-05 01:10 -0400
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-05 01:57 -0700
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-06 02:59 +1000
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-05 10:10 -0700
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-06 03:47 +1000
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-05 11:02 -0700
Re: silly circuit "Edward Rawde" <invalid@invalid.invalid> - 2026-04-05 14:07 -0400
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-05 12:23 -0700
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-06 15:01 +1000
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-06 07:25 -0700
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-07 03:47 +1000
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-06 12:08 -0700
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-07 16:34 +1000
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-07 11:02 -0700
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-08 23:28 +1000
Re: silly circuit piglet <erichpwagner@hotmail.com> - 2026-04-08 16:13 +0000
Re: silly circuit piglet <erichpwagner@hotmail.com> - 2026-04-07 15:58 +0100
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-07 09:00 -0700
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-08 23:48 +1000
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-08 09:41 -0700
Re: silly circuit "Edward Rawde" <invalid@invalid.invalid> - 2026-04-06 11:56 -0400
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-07 03:55 +1000
Re: silly circuit "Edward Rawde" <invalid@invalid.invalid> - 2026-04-06 14:12 -0400
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-07 16:05 +1000
Re: silly circuit "Edward Rawde" <invalid@invalid.invalid> - 2026-04-07 09:27 -0400
Re: silly circuit Bill Sloman <bill.sloman@ieee.org> - 2026-04-08 01:53 +1000
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-07 09:06 -0700
Re: silly circuit "Edward Rawde" <invalid@invalid.invalid> - 2026-04-07 12:46 -0400
Re: silly circuit john larkin <jl@glen--canyon.com> - 2026-04-07 11:31 -0700
Re: silly circuit "Edward Rawde" <invalid@invalid.invalid> - 2026-04-07 16:06 -0400
Re: silly circuit "Edward Rawde" <invalid@invalid.invalid> - 2026-04-07 16:12 -0400
Re: silly circuit JM <sunaecoNoChoppedPork@gmail.com> - 2026-04-08 00:50 +0100
Re: silly circuit "Edward Rawde" <invalid@invalid.invalid> - 2026-04-07 22:35 -0400
Re: silly circuit "Edward Rawde" <invalid@invalid.invalid> - 2026-04-05 22:16 -0400
Re: silly circuit piglet <erichpwagner@hotmail.com> - 2026-04-05 22:27 +0100
Re: silly circuit someone <2a59d59e3809f827ce709d3815e3950eef4a6a93af5557a93a7fdfba71460843@example.com> - 2026-04-09 03:45 +0000
A fully floating BJT-based LED current driver "Don" <g@crcomp.net> - 2026-04-09 09:17 +0000
Re: A fully floating BJT-based LED current driver JM <sunaecoNoChoppedPork@gmail.com> - 2026-04-09 16:16 +0100
Re: A fully floating BJT-based LED current driver "Don" <g@crcomp.net> - 2026-04-09 22:03 +0000
Re: A fully floating BJT-based LED current driver john larkin <jl@glen--canyon.com> - 2026-04-09 16:46 -0700
Re: A fully floating BJT-based LED current driver john larkin <jl@glen--canyon.com> - 2026-04-09 16:57 -0700
Re: A fully floating BJT-based LED current driver "Don" <g@crcomp.net> - 2026-04-10 03:24 +0000
Re: A fully floating BJT-based LED current driver JM <sunaecoNoChoppedPork@gmail.com> - 2026-04-10 17:34 +0100
Page 3 of 4 — ← Prev page 1 2 [3] 4 Next page →
| From | "Edward Rawde" <invalid@invalid.invalid> |
|---|---|
| Date | 2026-04-06 11:56 -0400 |
| Message-ID | <10r0l3j$5hs$1@nnrp.usenet.blueworldhosting.com> |
| In reply to | #742753 |
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qveo5$1sobp$1@dont-email.me... > On 6/04/2026 4:07 am, Edward Rawde wrote: >> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qu787$1ije3$1@dont-email.me... >>> On 6/04/2026 3:10 am, john larkin wrote: >>>> On Mon, 6 Apr 2026 02:59:12 +1000, Bill Sloman <bill.sloman@ieee.org> >>>> wrote: >>>> >>>>> On 5/04/2026 6:57 pm, john larkin wrote: >>>>>> On Sun, 5 Apr 2026 01:10:08 -0400, "Edward Rawde" >>>>>> <invalid@invalid.invalid> wrote: >>>>>> >>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qsnim$15pr5$1@dont-email.me... >>>>>>>> On 5/04/2026 12:37 pm, john larkin wrote: >>>>>>>>> On Sun, 5 Apr 2026 12:24:42 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>> wrote: >>>>>>>>> >>>>>>>>>> On 5/04/2026 11:07 am, john larkin wrote: >>>>>>>>>>> On Thu, 02 Apr 2026 13:56:47 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>>> wrote: >>>>> >>>>> <snip> >>>>> >>>>>> Let's see Bill's circuit next. >>>>> >>>>> You needed find somebody silly enough to take this nonsense seriously. >>>>> Edward Rawde is apparently willing to play with you. I'm happy to leave >>>>> you in his capable hands. >>>> >>>> Please don't think that I am mocking you for being unable to design >>>> simple circuits. That would be unkind. >>> >>> I can't see why you bothered to post the EDN circuit in the first place. >>> It's obvious how it works. Without a specific load there's not a lot of point in discussing it and plausible alternatives. >> > >>> You don't seem to have enough sense to realise this. I suppose I could mock you about that, but you do a pretty good job of >>> sending yourself up all on your own. > > > > What's hard to understand about two or more LXZ1-PB01 LEDs? > > 12V isn't hard to find. > > Nobody who actually wanted to use the circuit would talk about "two or more LXZ1-PB01 LEDs". Diodes tend to fail short. I have no information on the extent to which these LEDs fail short but do you want the others to die quicker or continue working normally? > John Larkin wants to see it as some kind of teaching exercise, not realising that he'd failed the course when he asked how it > would start up. Instructing people who don't know how to learn - and don't seem to want to - is a pointless exercise. > > -- > Bill Sloman, Sydney >
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| From | Bill Sloman <bill.sloman@ieee.org> |
|---|---|
| Date | 2026-04-07 03:55 +1000 |
| Message-ID | <10r0s20$28hv3$4@dont-email.me> |
| In reply to | #742765 |
On 7/04/2026 1:56 am, Edward Rawde wrote: > "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qveo5$1sobp$1@dont-email.me... >> On 6/04/2026 4:07 am, Edward Rawde wrote: >>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qu787$1ije3$1@dont-email.me... >>>> On 6/04/2026 3:10 am, john larkin wrote: >>>>> On Mon, 6 Apr 2026 02:59:12 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote: >>>>>> On 5/04/2026 6:57 pm, john larkin wrote: >>>>>>> On Sun, 5 Apr 2026 01:10:08 -0400, "Edward Rawde" >>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qsnim$15pr5$1@dont-email.me... >>>>>>>>> On 5/04/2026 12:37 pm, john larkin wrote: >>>>>>>>>> On Sun, 5 Apr 2026 12:24:42 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>> wrote: >>>>>>>>>>> On 5/04/2026 11:07 am, john larkin wrote: >>>>>>>>>>>> On Thu, 02 Apr 2026 13:56:47 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>>>> wrote: <snip> >>> What's hard to understand about two or more LXZ1-PB01 LEDs? >>> 12V isn't hard to find. >> >> Nobody who actually wanted to use the circuit would talk about "two or more LXZ1-PB01 LEDs". > > Diodes tend to fail short. I have no information on the extent to which these LEDs fail short but > do you want the others to die quicker or continue working normally? The circuit is a constant current driver. If enough LEDS fail short you might end up dissipating enough power in the driver to blow it up too, but until that happened the surviving LEDs will see exactly the same current as they did before the other LEDs failed. >> John Larkin wants to see it as some kind of teaching exercise, not realising that he'd failed the course when he asked how it >> would start up. Instructing people who don't know how to learn - and don't seem to want to - is a pointless exercise. -- Bill Sloman, Sydney
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| From | "Edward Rawde" <invalid@invalid.invalid> |
|---|---|
| Date | 2026-04-06 14:12 -0400 |
| Message-ID | <10r0t37$2cos$1@nnrp.usenet.blueworldhosting.com> |
| In reply to | #742780 |
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r0s20$28hv3$4@dont-email.me... > On 7/04/2026 1:56 am, Edward Rawde wrote: >> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qveo5$1sobp$1@dont-email.me... >>> On 6/04/2026 4:07 am, Edward Rawde wrote: >>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qu787$1ije3$1@dont-email.me... >>>>> On 6/04/2026 3:10 am, john larkin wrote: >>>>>> On Mon, 6 Apr 2026 02:59:12 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>> wrote: >>>>>>> On 5/04/2026 6:57 pm, john larkin wrote: >>>>>>>> On Sun, 5 Apr 2026 01:10:08 -0400, "Edward Rawde" >>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qsnim$15pr5$1@dont-email.me... >>>>>>>>>> On 5/04/2026 12:37 pm, john larkin wrote: >>>>>>>>>>> On Sun, 5 Apr 2026 12:24:42 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>>> wrote: >>>>>>>>>>>> On 5/04/2026 11:07 am, john larkin wrote: >>>>>>>>>>>>> On Thu, 02 Apr 2026 13:56:47 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>>>>> wrote: > > <snip> > >>>> What's hard to understand about two or more LXZ1-PB01 LEDs? >>>> 12V isn't hard to find. >>> >>> Nobody who actually wanted to use the circuit would talk about "two or more LXZ1-PB01 LEDs". >> >> Diodes tend to fail short. I have no information on the extent to which these LEDs fail short but >> do you want the others to die quicker or continue working normally? > > The circuit is a constant current driver. If enough LEDS fail short you might end up dissipating enough power in the driver to > blow it up too, but until that happened the surviving LEDs will see exactly the same current as they did before the other LEDs > failed. Thank you for your input, I will modify the specification as follows: Drive 500 mA +/- 50mA constant current though a string of 1,2,3 or 4 LXZ1-PB01 LEDs In the case of 0 LEDs (short circuit) no damage should occur and the current may be 500mA or lower. Cathode connection to LEDs should be grounded. Anode connection should be filtered as necessary so as to comply with CISPR 22 Class B. Input 12 - 15 V DC. High efficiency and low cost is required, depending on what can be achieved, so there is currently no exact target for efficiency or cost. Let me know when you have met this specification. Your design need not, of course, be anything like the design I posted. > >>> John Larkin wants to see it as some kind of teaching exercise, not realising that he'd failed the course when he asked how it >>> would start up. Instructing people who don't know how to learn - and don't seem to want to - is a pointless exercise. > > -- > Bill Sloman, Sydney > >
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| From | Bill Sloman <bill.sloman@ieee.org> |
|---|---|
| Date | 2026-04-07 16:05 +1000 |
| Message-ID | <10r26qm$2k1q7$2@dont-email.me> |
| In reply to | #742783 |
On 7/04/2026 4:12 am, Edward Rawde wrote: > "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r0s20$28hv3$4@dont-email.me... >> On 7/04/2026 1:56 am, Edward Rawde wrote: >>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qveo5$1sobp$1@dont-email.me... >>>> On 6/04/2026 4:07 am, Edward Rawde wrote: >>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qu787$1ije3$1@dont-email.me... >>>>>> On 6/04/2026 3:10 am, john larkin wrote: >>>>>>> On Mon, 6 Apr 2026 02:59:12 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>> wrote: >>>>>>>> On 5/04/2026 6:57 pm, john larkin wrote: >>>>>>>>> On Sun, 5 Apr 2026 01:10:08 -0400, "Edward Rawde" >>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qsnim$15pr5$1@dont-email.me... >>>>>>>>>>> On 5/04/2026 12:37 pm, john larkin wrote: >>>>>>>>>>>> On Sun, 5 Apr 2026 12:24:42 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>>>> wrote: >>>>>>>>>>>>> On 5/04/2026 11:07 am, john larkin wrote: >>>>>>>>>>>>>> On Thu, 02 Apr 2026 13:56:47 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>>>>>> wrote: >> >> <snip> >> >>>>> What's hard to understand about two or more LXZ1-PB01 LEDs? >>>>> 12V isn't hard to find. >>>> >>>> Nobody who actually wanted to use the circuit would talk about "two or more LXZ1-PB01 LEDs". >>> >>> Diodes tend to fail short. I have no information on the extent to which these LEDs fail short but >>> do you want the others to die quicker or continue working normally? >> >> The circuit is a constant current driver. If enough LEDS fail short you might end up dissipating enough power in the driver to >> blow it up too, but until that happened the surviving LEDs will see exactly the same current as they did before the other LEDs >> failed. > > Thank you for your input, I will modify the specification as follows: > > Drive 500 mA +/- 50mA constant current though a string of 1,2,3 or 4 LXZ1-PB01 LEDs > In the case of 0 LEDs (short circuit) no damage should occur and the current may be 500mA or lower. > Cathode connection to LEDs should be grounded. > Anode connection should be filtered as necessary so as to comply with CISPR 22 Class B. > Input 12 - 15 V DC. > High efficiency and low cost is required, depending on what can be achieved, > so there is currently no exact target for efficiency or cost. The EDN circuit specified BC557B and BC550B transistors https://www.onsemi.com/download/data-sheet/pdf/bc556b-d.pdf specifies an maximum continous current of 100mA, peak 200m https://www.onsemi.com/download/data-sheet/pdf/bc550-d.pdf specifies an maximum current of 100mA. They won't meet your specification. > Let me know when you have met this specification. Since the specification is nonsense in the context of this thread, I'm obviously not going to take it seriously. > Your design need not, of course, be anything like the design I posted. If you can't get the current levels right there's not a lot of point in looking at your "design'. I haven't done so because I don't take you all that seriously. >>>> John Larkin wants to see it as some kind of teaching exercise, not realising that he'd failed the course when he asked how it >>>> would start up. Instructing people who don't know how to learn - and don't seem to want to - is a pointless exercise. -- Bill Sloman, Sydney
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| From | "Edward Rawde" <invalid@invalid.invalid> |
|---|---|
| Date | 2026-04-07 09:27 -0400 |
| Message-ID | <10r30no$2gid$1@nnrp.usenet.blueworldhosting.com> |
| In reply to | #742796 |
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r26qm$2k1q7$2@dont-email.me... > On 7/04/2026 4:12 am, Edward Rawde wrote: >> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r0s20$28hv3$4@dont-email.me... >>> On 7/04/2026 1:56 am, Edward Rawde wrote: >>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qveo5$1sobp$1@dont-email.me... >>>>> On 6/04/2026 4:07 am, Edward Rawde wrote: >>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qu787$1ije3$1@dont-email.me... >>>>>>> On 6/04/2026 3:10 am, john larkin wrote: >>>>>>>> On Mon, 6 Apr 2026 02:59:12 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>> wrote: >>>>>>>>> On 5/04/2026 6:57 pm, john larkin wrote: >>>>>>>>>> On Sun, 5 Apr 2026 01:10:08 -0400, "Edward Rawde" >>>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qsnim$15pr5$1@dont-email.me... >>>>>>>>>>>> On 5/04/2026 12:37 pm, john larkin wrote: >>>>>>>>>>>>> On Sun, 5 Apr 2026 12:24:42 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>>>>> wrote: >>>>>>>>>>>>>> On 5/04/2026 11:07 am, john larkin wrote: >>>>>>>>>>>>>>> On Thu, 02 Apr 2026 13:56:47 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>>>>>>> wrote: >>> >>> <snip> >>> >>>>>> What's hard to understand about two or more LXZ1-PB01 LEDs? >>>>>> 12V isn't hard to find. >>>>> >>>>> Nobody who actually wanted to use the circuit would talk about "two or more LXZ1-PB01 LEDs". >>>> >>>> Diodes tend to fail short. I have no information on the extent to which these LEDs fail short but >>>> do you want the others to die quicker or continue working normally? >>> >>> The circuit is a constant current driver. If enough LEDS fail short you might end up dissipating enough power in the driver to >>> blow it up too, but until that happened the surviving LEDs will see exactly the same current as they did before the other LEDs >>> failed. >> >> Thank you for your input, I will modify the specification as follows: >> >> Drive 500 mA +/- 50mA constant current though a string of 1,2,3 or 4 LXZ1-PB01 LEDs >> In the case of 0 LEDs (short circuit) no damage should occur and the current may be 500mA or lower. >> Cathode connection to LEDs should be grounded. >> Anode connection should be filtered as necessary so as to comply with CISPR 22 Class B. >> Input 12 - 15 V DC. >> High efficiency and low cost is required, depending on what can be achieved, >> so there is currently no exact target for efficiency or cost. > > The EDN circuit specified BC557B and BC550B transistors > > https://www.onsemi.com/download/data-sheet/pdf/bc556b-d.pdf > specifies an maximum continous current of 100mA, peak 200m > > https://www.onsemi.com/download/data-sheet/pdf/bc550-d.pdf > specifies an maximum current of 100mA. > > They won't meet your specification. > >> Let me know when you have met this specification. > > Since the specification is nonsense in the context of this thread, I'm obviously not going to take it seriously. > >> Your design need not, of course, be anything like the design I posted. > > If you can't get the current levels right there's not a lot of point in looking at your "design'. I haven't done so because I > don't take you all that seriously. In other words you're not able to meet my specification which clearly requires more current than the EDN circuit. > >>>>> John Larkin wants to see it as some kind of teaching exercise, not realising that he'd failed the course when he asked how it >>>>> would start up. Instructing people who don't know how to learn - and don't seem to want to - is a pointless exercise. > > -- > Bill Sloman, Sydney >
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| From | Bill Sloman <bill.sloman@ieee.org> |
|---|---|
| Date | 2026-04-08 01:53 +1000 |
| Message-ID | <10r39a4$2ug99$1@dont-email.me> |
| In reply to | #742800 |
On 7/04/2026 11:27 pm, Edward Rawde wrote: > "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r26qm$2k1q7$2@dont-email.me... >> On 7/04/2026 4:12 am, Edward Rawde wrote: >>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r0s20$28hv3$4@dont-email.me... >>>> On 7/04/2026 1:56 am, Edward Rawde wrote: >>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qveo5$1sobp$1@dont-email.me... >>>>>> On 6/04/2026 4:07 am, Edward Rawde wrote: >>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qu787$1ije3$1@dont-email.me... >>>>>>>> On 6/04/2026 3:10 am, john larkin wrote: >>>>>>>>> On Mon, 6 Apr 2026 02:59:12 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>> wrote: >>>>>>>>>> On 5/04/2026 6:57 pm, john larkin wrote: >>>>>>>>>>> On Sun, 5 Apr 2026 01:10:08 -0400, "Edward Rawde" >>>>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qsnim$15pr5$1@dont-email.me... >>>>>>>>>>>>> On 5/04/2026 12:37 pm, john larkin wrote: >>>>>>>>>>>>>> On Sun, 5 Apr 2026 12:24:42 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>>>>>> wrote: >>>>>>>>>>>>>>> On 5/04/2026 11:07 am, john larkin wrote: >>>>>>>>>>>>>>>> On Thu, 02 Apr 2026 13:56:47 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>>>>>>>> wrote: >>>> >>>> <snip> >>>> >>>>>>> What's hard to understand about two or more LXZ1-PB01 LEDs? >>>>>>> 12V isn't hard to find. >>>>>> >>>>>> Nobody who actually wanted to use the circuit would talk about "two or more LXZ1-PB01 LEDs". >>>>> >>>>> Diodes tend to fail short. I have no information on the extent to which these LEDs fail short but >>>>> do you want the others to die quicker or continue working normally? >>>> >>>> The circuit is a constant current driver. If enough LEDS fail short you might end up dissipating enough power in the driver to >>>> blow it up too, but until that happened the surviving LEDs will see exactly the same current as they did before the other LEDs >>>> failed. >>> >>> Thank you for your input, I will modify the specification as follows: >>> >>> Drive 500 mA +/- 50mA constant current though a string of 1,2,3 or 4 LXZ1-PB01 LEDs >>> In the case of 0 LEDs (short circuit) no damage should occur and the current may be 500mA or lower. >>> Cathode connection to LEDs should be grounded. >>> Anode connection should be filtered as necessary so as to comply with CISPR 22 Class B. >>> Input 12 - 15 V DC. >>> High efficiency and low cost is required, depending on what can be achieved, >>> so there is currently no exact target for efficiency or cost. >> >> The EDN circuit specified BC557B and BC550B transistors >> >> https://www.onsemi.com/download/data-sheet/pdf/bc556b-d.pdf >> specifies an maximum continous current of 100mA, peak 200m >> >> https://www.onsemi.com/download/data-sheet/pdf/bc550-d.pdf >> specifies an maximum current of 100mA. >> >> They won't meet your specification. >> >>> Let me know when you have met this specification. >> >> Since the specification is nonsense in the context of this thread, I'm obviously not going to take it seriously. >> >>> Your design need not, of course, be anything like the design I posted. >> >> If you can't get the current levels right there's not a lot of point in looking at your "design'. I haven't done so because I >> don't take you all that seriously. > > In other words you're not able to meet my specification which clearly requires more > current than the EDN circuit. But you are posing a different kind of problem - not one that I would have any trouble solving, since I once set up a 20A constant current drive for xenon arc lamps and a bunch of them worked for years - but not one that has much to do with this thread, which did start with John Larkin bitching about the EDN circuit. >>>>>> John Larkin wants to see it as some kind of teaching exercise, not realising that he'd failed the course when he asked how it >>>>>> would start up. Instructing people who don't know how to learn - and don't seem to want to - is a pointless exercise. -- Bill Sloman, Sydney
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| From | john larkin <jl@glen--canyon.com> |
|---|---|
| Date | 2026-04-07 09:06 -0700 |
| Message-ID | <hjaatk1mged6g36r5r9iej70btidivgq0t@4ax.com> |
| In reply to | #742800 |
On Tue, 7 Apr 2026 09:27:18 -0400, "Edward Rawde" <invalid@invalid.invalid> wrote: >"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r26qm$2k1q7$2@dont-email.me... >> On 7/04/2026 4:12 am, Edward Rawde wrote: >>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r0s20$28hv3$4@dont-email.me... >>>> On 7/04/2026 1:56 am, Edward Rawde wrote: >>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qveo5$1sobp$1@dont-email.me... >>>>>> On 6/04/2026 4:07 am, Edward Rawde wrote: >>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qu787$1ije3$1@dont-email.me... >>>>>>>> On 6/04/2026 3:10 am, john larkin wrote: >>>>>>>>> On Mon, 6 Apr 2026 02:59:12 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>> wrote: >>>>>>>>>> On 5/04/2026 6:57 pm, john larkin wrote: >>>>>>>>>>> On Sun, 5 Apr 2026 01:10:08 -0400, "Edward Rawde" >>>>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qsnim$15pr5$1@dont-email.me... >>>>>>>>>>>>> On 5/04/2026 12:37 pm, john larkin wrote: >>>>>>>>>>>>>> On Sun, 5 Apr 2026 12:24:42 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>>>>>> wrote: >>>>>>>>>>>>>>> On 5/04/2026 11:07 am, john larkin wrote: >>>>>>>>>>>>>>>> On Thu, 02 Apr 2026 13:56:47 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>>>>>>>> wrote: >>>> >>>> <snip> >>>> >>>>>>> What's hard to understand about two or more LXZ1-PB01 LEDs? >>>>>>> 12V isn't hard to find. >>>>>> >>>>>> Nobody who actually wanted to use the circuit would talk about "two or more LXZ1-PB01 LEDs". >>>>> >>>>> Diodes tend to fail short. I have no information on the extent to which these LEDs fail short but >>>>> do you want the others to die quicker or continue working normally? >>>> >>>> The circuit is a constant current driver. If enough LEDS fail short you might end up dissipating enough power in the driver to >>>> blow it up too, but until that happened the surviving LEDs will see exactly the same current as they did before the other LEDs >>>> failed. >>> >>> Thank you for your input, I will modify the specification as follows: >>> >>> Drive 500 mA +/- 50mA constant current though a string of 1,2,3 or 4 LXZ1-PB01 LEDs >>> In the case of 0 LEDs (short circuit) no damage should occur and the current may be 500mA or lower. >>> Cathode connection to LEDs should be grounded. >>> Anode connection should be filtered as necessary so as to comply with CISPR 22 Class B. >>> Input 12 - 15 V DC. >>> High efficiency and low cost is required, depending on what can be achieved, >>> so there is currently no exact target for efficiency or cost. >> >> The EDN circuit specified BC557B and BC550B transistors >> >> https://www.onsemi.com/download/data-sheet/pdf/bc556b-d.pdf >> specifies an maximum continous current of 100mA, peak 200m >> >> https://www.onsemi.com/download/data-sheet/pdf/bc550-d.pdf >> specifies an maximum current of 100mA. >> >> They won't meet your specification. >> >>> Let me know when you have met this specification. >> >> Since the specification is nonsense in the context of this thread, I'm obviously not going to take it seriously. >> >>> Your design need not, of course, be anything like the design I posted. >> >> If you can't get the current levels right there's not a lot of point in looking at your "design'. I haven't done so because I >> don't take you all that seriously. > >In other words you're not able to meet my specification which clearly requires more >current than the EDN circuit. > Take a look at the cute little TI switchers, like TPS562208. Simple, spread-spectrum, cheap. We pay 21 cents for that one. There are higher voltage parts in the family. I think one could design a switchmode 500 mA LED current limiter with that chip and maybe 5 cheap passives. John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics
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| From | "Edward Rawde" <invalid@invalid.invalid> |
|---|---|
| Date | 2026-04-07 12:46 -0400 |
| Message-ID | <10r3cdq$18a5$1@nnrp.usenet.blueworldhosting.com> |
| In reply to | #742804 |
"john larkin" <jl@glen--canyon.com> wrote in message news:hjaatk1mged6g36r5r9iej70btidivgq0t@4ax.com... > On Tue, 7 Apr 2026 09:27:18 -0400, "Edward Rawde" > <invalid@invalid.invalid> wrote: > >>"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r26qm$2k1q7$2@dont-email.me... >>> On 7/04/2026 4:12 am, Edward Rawde wrote: >>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r0s20$28hv3$4@dont-email.me... >>>>> On 7/04/2026 1:56 am, Edward Rawde wrote: >>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qveo5$1sobp$1@dont-email.me... >>>>>>> On 6/04/2026 4:07 am, Edward Rawde wrote: >>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qu787$1ije3$1@dont-email.me... >>>>>>>>> On 6/04/2026 3:10 am, john larkin wrote: >>>>>>>>>> On Mon, 6 Apr 2026 02:59:12 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>> wrote: >>>>>>>>>>> On 5/04/2026 6:57 pm, john larkin wrote: >>>>>>>>>>>> On Sun, 5 Apr 2026 01:10:08 -0400, "Edward Rawde" >>>>>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qsnim$15pr5$1@dont-email.me... >>>>>>>>>>>>>> On 5/04/2026 12:37 pm, john larkin wrote: >>>>>>>>>>>>>>> On Sun, 5 Apr 2026 12:24:42 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>>>>>>> wrote: >>>>>>>>>>>>>>>> On 5/04/2026 11:07 am, john larkin wrote: >>>>>>>>>>>>>>>>> On Thu, 02 Apr 2026 13:56:47 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>>>>>>>>> wrote: >>>>> >>>>> <snip> >>>>> >>>>>>>> What's hard to understand about two or more LXZ1-PB01 LEDs? >>>>>>>> 12V isn't hard to find. >>>>>>> >>>>>>> Nobody who actually wanted to use the circuit would talk about "two or more LXZ1-PB01 LEDs". >>>>>> >>>>>> Diodes tend to fail short. I have no information on the extent to which these LEDs fail short but >>>>>> do you want the others to die quicker or continue working normally? >>>>> >>>>> The circuit is a constant current driver. If enough LEDS fail short you might end up dissipating enough power in the driver to >>>>> blow it up too, but until that happened the surviving LEDs will see exactly the same current as they did before the other LEDs >>>>> failed. >>>> >>>> Thank you for your input, I will modify the specification as follows: >>>> >>>> Drive 500 mA +/- 50mA constant current though a string of 1,2,3 or 4 LXZ1-PB01 LEDs >>>> In the case of 0 LEDs (short circuit) no damage should occur and the current may be 500mA or lower. >>>> Cathode connection to LEDs should be grounded. >>>> Anode connection should be filtered as necessary so as to comply with CISPR 22 Class B. >>>> Input 12 - 15 V DC. >>>> High efficiency and low cost is required, depending on what can be achieved, >>>> so there is currently no exact target for efficiency or cost. >>> >>> The EDN circuit specified BC557B and BC550B transistors >>> >>> https://www.onsemi.com/download/data-sheet/pdf/bc556b-d.pdf >>> specifies an maximum continous current of 100mA, peak 200m >>> >>> https://www.onsemi.com/download/data-sheet/pdf/bc550-d.pdf >>> specifies an maximum current of 100mA. >>> >>> They won't meet your specification. >>> >>>> Let me know when you have met this specification. >>> >>> Since the specification is nonsense in the context of this thread, I'm obviously not going to take it seriously. >>> >>>> Your design need not, of course, be anything like the design I posted. >>> >>> If you can't get the current levels right there's not a lot of point in looking at your "design'. I haven't done so because I >>> don't take you all that seriously. >> >>In other words you're not able to meet my specification which clearly requires more >>current than the EDN circuit. >> > > Take a look at the cute little TI switchers, like TPS562208. Simple, > spread-spectrum, cheap. We pay 21 cents for that one. There are higher > voltage parts in the family. > > I think one could design a switchmode 500 mA LED current limiter with > that chip and maybe 5 cheap passives. Do any similar parts exist which have LTSpice models? > > > John Larkin > Highland Tech Glen Canyon Design Center > Lunatic Fringe Electronics
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| From | john larkin <jl@glen--canyon.com> |
|---|---|
| Date | 2026-04-07 11:31 -0700 |
| Message-ID | <jviatklk108hs6oad36v8hdlpg90u5irl2@4ax.com> |
| In reply to | #742805 |
On Tue, 7 Apr 2026 12:46:49 -0400, "Edward Rawde" <invalid@invalid.invalid> wrote: >"john larkin" <jl@glen--canyon.com> wrote in message news:hjaatk1mged6g36r5r9iej70btidivgq0t@4ax.com... >> On Tue, 7 Apr 2026 09:27:18 -0400, "Edward Rawde" >> <invalid@invalid.invalid> wrote: >> >>>"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r26qm$2k1q7$2@dont-email.me... >>>> On 7/04/2026 4:12 am, Edward Rawde wrote: >>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r0s20$28hv3$4@dont-email.me... >>>>>> On 7/04/2026 1:56 am, Edward Rawde wrote: >>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qveo5$1sobp$1@dont-email.me... >>>>>>>> On 6/04/2026 4:07 am, Edward Rawde wrote: >>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qu787$1ije3$1@dont-email.me... >>>>>>>>>> On 6/04/2026 3:10 am, john larkin wrote: >>>>>>>>>>> On Mon, 6 Apr 2026 02:59:12 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>>> wrote: >>>>>>>>>>>> On 5/04/2026 6:57 pm, john larkin wrote: >>>>>>>>>>>>> On Sun, 5 Apr 2026 01:10:08 -0400, "Edward Rawde" >>>>>>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qsnim$15pr5$1@dont-email.me... >>>>>>>>>>>>>>> On 5/04/2026 12:37 pm, john larkin wrote: >>>>>>>>>>>>>>>> On Sun, 5 Apr 2026 12:24:42 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>>>>>>>> wrote: >>>>>>>>>>>>>>>>> On 5/04/2026 11:07 am, john larkin wrote: >>>>>>>>>>>>>>>>>> On Thu, 02 Apr 2026 13:56:47 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>>>>>>>>>> wrote: >>>>>> >>>>>> <snip> >>>>>> >>>>>>>>> What's hard to understand about two or more LXZ1-PB01 LEDs? >>>>>>>>> 12V isn't hard to find. >>>>>>>> >>>>>>>> Nobody who actually wanted to use the circuit would talk about "two or more LXZ1-PB01 LEDs". >>>>>>> >>>>>>> Diodes tend to fail short. I have no information on the extent to which these LEDs fail short but >>>>>>> do you want the others to die quicker or continue working normally? >>>>>> >>>>>> The circuit is a constant current driver. If enough LEDS fail short you might end up dissipating enough power in the driver to >>>>>> blow it up too, but until that happened the surviving LEDs will see exactly the same current as they did before the other LEDs >>>>>> failed. >>>>> >>>>> Thank you for your input, I will modify the specification as follows: >>>>> >>>>> Drive 500 mA +/- 50mA constant current though a string of 1,2,3 or 4 LXZ1-PB01 LEDs >>>>> In the case of 0 LEDs (short circuit) no damage should occur and the current may be 500mA or lower. >>>>> Cathode connection to LEDs should be grounded. >>>>> Anode connection should be filtered as necessary so as to comply with CISPR 22 Class B. >>>>> Input 12 - 15 V DC. >>>>> High efficiency and low cost is required, depending on what can be achieved, >>>>> so there is currently no exact target for efficiency or cost. >>>> >>>> The EDN circuit specified BC557B and BC550B transistors >>>> >>>> https://www.onsemi.com/download/data-sheet/pdf/bc556b-d.pdf >>>> specifies an maximum continous current of 100mA, peak 200m >>>> >>>> https://www.onsemi.com/download/data-sheet/pdf/bc550-d.pdf >>>> specifies an maximum current of 100mA. >>>> >>>> They won't meet your specification. >>>> >>>>> Let me know when you have met this specification. >>>> >>>> Since the specification is nonsense in the context of this thread, I'm obviously not going to take it seriously. >>>> >>>>> Your design need not, of course, be anything like the design I posted. >>>> >>>> If you can't get the current levels right there's not a lot of point in looking at your "design'. I haven't done so because I >>>> don't take you all that seriously. >>> >>>In other words you're not able to meet my specification which clearly requires more >>>current than the EDN circuit. >>> >> >> Take a look at the cute little TI switchers, like TPS562208. Simple, >> spread-spectrum, cheap. We pay 21 cents for that one. There are higher >> voltage parts in the family. >> >> I think one could design a switchmode 500 mA LED current limiter with >> that chip and maybe 5 cheap passives. > >Do any similar parts exist which have LTSpice models? > >> >> >> John Larkin >> Highland Tech Glen Canyon Design Center >> Lunatic Fringe Electronics > TI has Pspice models of many of their parts. I don't have much luck importing them into LT Spice, but I know that it can be done. I'd like to find someone to do that for me now and then, pick up something like the TPS chip and deliver a working LT sim. https://www.electronics-related.com/showthread/sci.electronics.design/892705-1.php It wouldn't be hard to breadboard the circuit. John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics
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| From | "Edward Rawde" <invalid@invalid.invalid> |
|---|---|
| Date | 2026-04-07 16:06 -0400 |
| Message-ID | <10r3o3u$vq7$1@nnrp.usenet.blueworldhosting.com> |
| In reply to | #742807 |
"john larkin" <jl@glen--canyon.com> wrote in message news:jviatklk108hs6oad36v8hdlpg90u5irl2@4ax.com... > On Tue, 7 Apr 2026 12:46:49 -0400, "Edward Rawde" > <invalid@invalid.invalid> wrote: > >>"john larkin" <jl@glen--canyon.com> wrote in message news:hjaatk1mged6g36r5r9iej70btidivgq0t@4ax.com... >>> On Tue, 7 Apr 2026 09:27:18 -0400, "Edward Rawde" >>> <invalid@invalid.invalid> wrote: >>> >>>>"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r26qm$2k1q7$2@dont-email.me... >>>>> On 7/04/2026 4:12 am, Edward Rawde wrote: >>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r0s20$28hv3$4@dont-email.me... >>>>>>> On 7/04/2026 1:56 am, Edward Rawde wrote: >>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qveo5$1sobp$1@dont-email.me... >>>>>>>>> On 6/04/2026 4:07 am, Edward Rawde wrote: >>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qu787$1ije3$1@dont-email.me... >>>>>>>>>>> On 6/04/2026 3:10 am, john larkin wrote: >>>>>>>>>>>> On Mon, 6 Apr 2026 02:59:12 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>>>> wrote: >>>>>>>>>>>>> On 5/04/2026 6:57 pm, john larkin wrote: >>>>>>>>>>>>>> On Sun, 5 Apr 2026 01:10:08 -0400, "Edward Rawde" >>>>>>>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qsnim$15pr5$1@dont-email.me... >>>>>>>>>>>>>>>> On 5/04/2026 12:37 pm, john larkin wrote: >>>>>>>>>>>>>>>>> On Sun, 5 Apr 2026 12:24:42 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>>>>>>>>> wrote: >>>>>>>>>>>>>>>>>> On 5/04/2026 11:07 am, john larkin wrote: >>>>>>>>>>>>>>>>>>> On Thu, 02 Apr 2026 13:56:47 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>>>>>>>>>>> wrote: >>>>>>> >>>>>>> <snip> >>>>>>> >>>>>>>>>> What's hard to understand about two or more LXZ1-PB01 LEDs? >>>>>>>>>> 12V isn't hard to find. >>>>>>>>> >>>>>>>>> Nobody who actually wanted to use the circuit would talk about "two or more LXZ1-PB01 LEDs". >>>>>>>> >>>>>>>> Diodes tend to fail short. I have no information on the extent to which these LEDs fail short but >>>>>>>> do you want the others to die quicker or continue working normally? >>>>>>> >>>>>>> The circuit is a constant current driver. If enough LEDS fail short you might end up dissipating enough power in the driver >>>>>>> to >>>>>>> blow it up too, but until that happened the surviving LEDs will see exactly the same current as they did before the other >>>>>>> LEDs >>>>>>> failed. >>>>>> >>>>>> Thank you for your input, I will modify the specification as follows: >>>>>> >>>>>> Drive 500 mA +/- 50mA constant current though a string of 1,2,3 or 4 LXZ1-PB01 LEDs >>>>>> In the case of 0 LEDs (short circuit) no damage should occur and the current may be 500mA or lower. >>>>>> Cathode connection to LEDs should be grounded. >>>>>> Anode connection should be filtered as necessary so as to comply with CISPR 22 Class B. >>>>>> Input 12 - 15 V DC. >>>>>> High efficiency and low cost is required, depending on what can be achieved, >>>>>> so there is currently no exact target for efficiency or cost. >>>>> >>>>> The EDN circuit specified BC557B and BC550B transistors >>>>> >>>>> https://www.onsemi.com/download/data-sheet/pdf/bc556b-d.pdf >>>>> specifies an maximum continous current of 100mA, peak 200m >>>>> >>>>> https://www.onsemi.com/download/data-sheet/pdf/bc550-d.pdf >>>>> specifies an maximum current of 100mA. >>>>> >>>>> They won't meet your specification. >>>>> >>>>>> Let me know when you have met this specification. >>>>> >>>>> Since the specification is nonsense in the context of this thread, I'm obviously not going to take it seriously. >>>>> >>>>>> Your design need not, of course, be anything like the design I posted. >>>>> >>>>> If you can't get the current levels right there's not a lot of point in looking at your "design'. I haven't done so because I >>>>> don't take you all that seriously. >>>> >>>>In other words you're not able to meet my specification which clearly requires more >>>>current than the EDN circuit. >>>> >>> >>> Take a look at the cute little TI switchers, like TPS562208. Simple, >>> spread-spectrum, cheap. We pay 21 cents for that one. There are higher >>> voltage parts in the family. >>> >>> I think one could design a switchmode 500 mA LED current limiter with >>> that chip and maybe 5 cheap passives. >> >>Do any similar parts exist which have LTSpice models? >> >>> >>> >>> John Larkin >>> Highland Tech Glen Canyon Design Center >>> Lunatic Fringe Electronics >> > > TI has Pspice models of many of their parts. I don't have much luck > importing them into LT Spice, but I know that it can be done. > > I'd like to find someone to do that for me now and then, pick up > something like the TPS chip and deliver a working LT sim. I got TPS54302.LIB and made a symbol. The pin names don't match but presumably PH is SW and VSENSE is FB. I then tried to make Fig 7-1 in the data sheet but although it runs it does not so far do anything useful. > > https://www.electronics-related.com/showthread/sci.electronics.design/892705-1.php > > It wouldn't be hard to breadboard the circuit. > > > John Larkin > Highland Tech Glen Canyon Design Center > Lunatic Fringe Electronics
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| From | "Edward Rawde" <invalid@invalid.invalid> |
|---|---|
| Date | 2026-04-07 16:12 -0400 |
| Message-ID | <10r3of1$90n$1@nnrp.usenet.blueworldhosting.com> |
| In reply to | #742811 |
"Edward Rawde" <invalid@invalid.invalid> wrote in message news:10r3o3u$vq7$1@nnrp.usenet.blueworldhosting.com... > "john larkin" <jl@glen--canyon.com> wrote in message news:jviatklk108hs6oad36v8hdlpg90u5irl2@4ax.com... >> On Tue, 7 Apr 2026 12:46:49 -0400, "Edward Rawde" >> <invalid@invalid.invalid> wrote: >> >>>"john larkin" <jl@glen--canyon.com> wrote in message news:hjaatk1mged6g36r5r9iej70btidivgq0t@4ax.com... >>>> On Tue, 7 Apr 2026 09:27:18 -0400, "Edward Rawde" >>>> <invalid@invalid.invalid> wrote: >>>> >>>>>"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r26qm$2k1q7$2@dont-email.me... >>>>>> On 7/04/2026 4:12 am, Edward Rawde wrote: >>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r0s20$28hv3$4@dont-email.me... >>>>>>>> On 7/04/2026 1:56 am, Edward Rawde wrote: >>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qveo5$1sobp$1@dont-email.me... >>>>>>>>>> On 6/04/2026 4:07 am, Edward Rawde wrote: >>>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qu787$1ije3$1@dont-email.me... >>>>>>>>>>>> On 6/04/2026 3:10 am, john larkin wrote: >>>>>>>>>>>>> On Mon, 6 Apr 2026 02:59:12 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>>>>> wrote: >>>>>>>>>>>>>> On 5/04/2026 6:57 pm, john larkin wrote: >>>>>>>>>>>>>>> On Sun, 5 Apr 2026 01:10:08 -0400, "Edward Rawde" >>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qsnim$15pr5$1@dont-email.me... >>>>>>>>>>>>>>>>> On 5/04/2026 12:37 pm, john larkin wrote: >>>>>>>>>>>>>>>>>> On Sun, 5 Apr 2026 12:24:42 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>>>>>>>>>> wrote: >>>>>>>>>>>>>>>>>>> On 5/04/2026 11:07 am, john larkin wrote: >>>>>>>>>>>>>>>>>>>> On Thu, 02 Apr 2026 13:56:47 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>>>>>>>>>>>> wrote: >>>>>>>> >>>>>>>> <snip> >>>>>>>> >>>>>>>>>>> What's hard to understand about two or more LXZ1-PB01 LEDs? >>>>>>>>>>> 12V isn't hard to find. >>>>>>>>>> >>>>>>>>>> Nobody who actually wanted to use the circuit would talk about "two or more LXZ1-PB01 LEDs". >>>>>>>>> >>>>>>>>> Diodes tend to fail short. I have no information on the extent to which these LEDs fail short but >>>>>>>>> do you want the others to die quicker or continue working normally? >>>>>>>> >>>>>>>> The circuit is a constant current driver. If enough LEDS fail short you might end up dissipating enough power in the driver >>>>>>>> to >>>>>>>> blow it up too, but until that happened the surviving LEDs will see exactly the same current as they did before the other >>>>>>>> LEDs >>>>>>>> failed. >>>>>>> >>>>>>> Thank you for your input, I will modify the specification as follows: >>>>>>> >>>>>>> Drive 500 mA +/- 50mA constant current though a string of 1,2,3 or 4 LXZ1-PB01 LEDs >>>>>>> In the case of 0 LEDs (short circuit) no damage should occur and the current may be 500mA or lower. >>>>>>> Cathode connection to LEDs should be grounded. >>>>>>> Anode connection should be filtered as necessary so as to comply with CISPR 22 Class B. >>>>>>> Input 12 - 15 V DC. >>>>>>> High efficiency and low cost is required, depending on what can be achieved, >>>>>>> so there is currently no exact target for efficiency or cost. >>>>>> >>>>>> The EDN circuit specified BC557B and BC550B transistors >>>>>> >>>>>> https://www.onsemi.com/download/data-sheet/pdf/bc556b-d.pdf >>>>>> specifies an maximum continous current of 100mA, peak 200m >>>>>> >>>>>> https://www.onsemi.com/download/data-sheet/pdf/bc550-d.pdf >>>>>> specifies an maximum current of 100mA. >>>>>> >>>>>> They won't meet your specification. >>>>>> >>>>>>> Let me know when you have met this specification. >>>>>> >>>>>> Since the specification is nonsense in the context of this thread, I'm obviously not going to take it seriously. >>>>>> >>>>>>> Your design need not, of course, be anything like the design I posted. >>>>>> >>>>>> If you can't get the current levels right there's not a lot of point in looking at your "design'. I haven't done so because I >>>>>> don't take you all that seriously. >>>>> >>>>>In other words you're not able to meet my specification which clearly requires more >>>>>current than the EDN circuit. >>>>> >>>> >>>> Take a look at the cute little TI switchers, like TPS562208. Simple, >>>> spread-spectrum, cheap. We pay 21 cents for that one. There are higher >>>> voltage parts in the family. >>>> >>>> I think one could design a switchmode 500 mA LED current limiter with >>>> that chip and maybe 5 cheap passives. >>> >>>Do any similar parts exist which have LTSpice models? >>> >>>> >>>> >>>> John Larkin >>>> Highland Tech Glen Canyon Design Center >>>> Lunatic Fringe Electronics >>> >> >> TI has Pspice models of many of their parts. I don't have much luck >> importing them into LT Spice, but I know that it can be done. >> >> I'd like to find someone to do that for me now and then, pick up >> something like the TPS chip and deliver a working LT sim. > > I got TPS54302.LIB and made a symbol. The pin names don't match but presumably PH is SW > and VSENSE is FB. > > I then tried to make Fig 7-1 in the data sheet but although it runs it does not so far do anything useful. News just in. The alternate solver produces 5V at 3A into 1.7 ohm. Switching looks fine. > >> >> https://www.electronics-related.com/showthread/sci.electronics.design/892705-1.php >> >> It wouldn't be hard to breadboard the circuit. >> >> >> John Larkin >> Highland Tech Glen Canyon Design Center >> Lunatic Fringe Electronics > >
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| From | JM <sunaecoNoChoppedPork@gmail.com> |
|---|---|
| Date | 2026-04-08 00:50 +0100 |
| Message-ID | <mm5btkt1uc84ijgbkue7rqfqr8448ubb12@4ax.com> |
| In reply to | #742812 |
On Tue, 7 Apr 2026 16:12:15 -0400, "Edward Rawde" <invalid@invalid.invalid> wrote: >"Edward Rawde" <invalid@invalid.invalid> wrote in message news:10r3o3u$vq7$1@nnrp.usenet.blueworldhosting.com... >> "john larkin" <jl@glen--canyon.com> wrote in message news:jviatklk108hs6oad36v8hdlpg90u5irl2@4ax.com... >>> On Tue, 7 Apr 2026 12:46:49 -0400, "Edward Rawde" >>> <invalid@invalid.invalid> wrote: >>> >>>>"john larkin" <jl@glen--canyon.com> wrote in message news:hjaatk1mged6g36r5r9iej70btidivgq0t@4ax.com... >>>>> On Tue, 7 Apr 2026 09:27:18 -0400, "Edward Rawde" >>>>> <invalid@invalid.invalid> wrote: >>>>> >>>>>>"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r26qm$2k1q7$2@dont-email.me... >>>>>>> On 7/04/2026 4:12 am, Edward Rawde wrote: >>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r0s20$28hv3$4@dont-email.me... >>>>>>>>> On 7/04/2026 1:56 am, Edward Rawde wrote: >>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qveo5$1sobp$1@dont-email.me... >>>>>>>>>>> On 6/04/2026 4:07 am, Edward Rawde wrote: >>>>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qu787$1ije3$1@dont-email.me... >>>>>>>>>>>>> On 6/04/2026 3:10 am, john larkin wrote: >>>>>>>>>>>>>> On Mon, 6 Apr 2026 02:59:12 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>>>>>> wrote: >>>>>>>>>>>>>>> On 5/04/2026 6:57 pm, john larkin wrote: >>>>>>>>>>>>>>>> On Sun, 5 Apr 2026 01:10:08 -0400, "Edward Rawde" >>>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qsnim$15pr5$1@dont-email.me... >>>>>>>>>>>>>>>>>> On 5/04/2026 12:37 pm, john larkin wrote: >>>>>>>>>>>>>>>>>>> On Sun, 5 Apr 2026 12:24:42 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>>>>>>>>>>> wrote: >>>>>>>>>>>>>>>>>>>> On 5/04/2026 11:07 am, john larkin wrote: >>>>>>>>>>>>>>>>>>>>> On Thu, 02 Apr 2026 13:56:47 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>>>>>>>>>>>>> wrote: >>>>>>>>> >>>>>>>>> <snip> >>>>>>>>> >>>>>>>>>>>> What's hard to understand about two or more LXZ1-PB01 LEDs? >>>>>>>>>>>> 12V isn't hard to find. >>>>>>>>>>> >>>>>>>>>>> Nobody who actually wanted to use the circuit would talk about "two or more LXZ1-PB01 LEDs". >>>>>>>>>> >>>>>>>>>> Diodes tend to fail short. I have no information on the extent to which these LEDs fail short but >>>>>>>>>> do you want the others to die quicker or continue working normally? >>>>>>>>> >>>>>>>>> The circuit is a constant current driver. If enough LEDS fail short you might end up dissipating enough power in the driver >>>>>>>>> to >>>>>>>>> blow it up too, but until that happened the surviving LEDs will see exactly the same current as they did before the other >>>>>>>>> LEDs >>>>>>>>> failed. >>>>>>>> >>>>>>>> Thank you for your input, I will modify the specification as follows: >>>>>>>> >>>>>>>> Drive 500 mA +/- 50mA constant current though a string of 1,2,3 or 4 LXZ1-PB01 LEDs >>>>>>>> In the case of 0 LEDs (short circuit) no damage should occur and the current may be 500mA or lower. >>>>>>>> Cathode connection to LEDs should be grounded. >>>>>>>> Anode connection should be filtered as necessary so as to comply with CISPR 22 Class B. >>>>>>>> Input 12 - 15 V DC. >>>>>>>> High efficiency and low cost is required, depending on what can be achieved, >>>>>>>> so there is currently no exact target for efficiency or cost. >>>>>>> >>>>>>> The EDN circuit specified BC557B and BC550B transistors >>>>>>> >>>>>>> https://www.onsemi.com/download/data-sheet/pdf/bc556b-d.pdf >>>>>>> specifies an maximum continous current of 100mA, peak 200m >>>>>>> >>>>>>> https://www.onsemi.com/download/data-sheet/pdf/bc550-d.pdf >>>>>>> specifies an maximum current of 100mA. >>>>>>> >>>>>>> They won't meet your specification. >>>>>>> >>>>>>>> Let me know when you have met this specification. >>>>>>> >>>>>>> Since the specification is nonsense in the context of this thread, I'm obviously not going to take it seriously. >>>>>>> >>>>>>>> Your design need not, of course, be anything like the design I posted. >>>>>>> >>>>>>> If you can't get the current levels right there's not a lot of point in looking at your "design'. I haven't done so because I >>>>>>> don't take you all that seriously. >>>>>> >>>>>>In other words you're not able to meet my specification which clearly requires more >>>>>>current than the EDN circuit. >>>>>> >>>>> >>>>> Take a look at the cute little TI switchers, like TPS562208. Simple, >>>>> spread-spectrum, cheap. We pay 21 cents for that one. There are higher >>>>> voltage parts in the family. >>>>> >>>>> I think one could design a switchmode 500 mA LED current limiter with >>>>> that chip and maybe 5 cheap passives. >>>> >>>>Do any similar parts exist which have LTSpice models? >>>> >>>>> >>>>> >>>>> John Larkin >>>>> Highland Tech Glen Canyon Design Center >>>>> Lunatic Fringe Electronics >>>> >>> >>> TI has Pspice models of many of their parts. I don't have much luck >>> importing them into LT Spice, but I know that it can be done. >>> >>> I'd like to find someone to do that for me now and then, pick up >>> something like the TPS chip and deliver a working LT sim. >> >> I got TPS54302.LIB and made a symbol. The pin names don't match but presumably PH is SW >> and VSENSE is FB. >> >> I then tried to make Fig 7-1 in the data sheet but although it runs it does not so far do anything useful. > >News just in. The alternate solver produces 5V at 3A into 1.7 ohm. Switching looks fine. > >> Be careful - LTSpice can have lots of problems with pspice syntax which are not always apparent. Simulations can appear to run but in fact generate bollocks. LTSpice 26 is a great improvment over earlier versions in this regard. Attached is a TPS562208 sim - it looks OK in 26, but will run incorrectly in 25. https://mega.nz/file/g8EVHD7Z#4MDojAygdgfvhsauUKhFyutfCrkK3Q-_EHpxWMNtT2o -- This email has been checked for viruses by Avast antivirus software. www.avast.com
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| From | "Edward Rawde" <invalid@invalid.invalid> |
|---|---|
| Date | 2026-04-07 22:35 -0400 |
| Message-ID | <10r4etl$db6$1@nnrp.usenet.blueworldhosting.com> |
| In reply to | #742815 |
"JM" <sunaecoNoChoppedPork@gmail.com> wrote in message news:mm5btkt1uc84ijgbkue7rqfqr8448ubb12@4ax.com... > On Tue, 7 Apr 2026 16:12:15 -0400, "Edward Rawde" > <invalid@invalid.invalid> wrote: > >>"Edward Rawde" <invalid@invalid.invalid> wrote in message news:10r3o3u$vq7$1@nnrp.usenet.blueworldhosting.com... >>> "john larkin" <jl@glen--canyon.com> wrote in message news:jviatklk108hs6oad36v8hdlpg90u5irl2@4ax.com... >>>> On Tue, 7 Apr 2026 12:46:49 -0400, "Edward Rawde" >>>> <invalid@invalid.invalid> wrote: >>>> >>>>>"john larkin" <jl@glen--canyon.com> wrote in message news:hjaatk1mged6g36r5r9iej70btidivgq0t@4ax.com... >>>>>> On Tue, 7 Apr 2026 09:27:18 -0400, "Edward Rawde" >>>>>> <invalid@invalid.invalid> wrote: >>>>>> >>>>>>>"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r26qm$2k1q7$2@dont-email.me... >>>>>>>> On 7/04/2026 4:12 am, Edward Rawde wrote: >>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10r0s20$28hv3$4@dont-email.me... >>>>>>>>>> On 7/04/2026 1:56 am, Edward Rawde wrote: >>>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qveo5$1sobp$1@dont-email.me... >>>>>>>>>>>> On 6/04/2026 4:07 am, Edward Rawde wrote: >>>>>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qu787$1ije3$1@dont-email.me... >>>>>>>>>>>>>> On 6/04/2026 3:10 am, john larkin wrote: >>>>>>>>>>>>>>> On Mon, 6 Apr 2026 02:59:12 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>>>>>>> wrote: >>>>>>>>>>>>>>>> On 5/04/2026 6:57 pm, john larkin wrote: >>>>>>>>>>>>>>>>> On Sun, 5 Apr 2026 01:10:08 -0400, "Edward Rawde" >>>>>>>>>>>>>>>>> <invalid@invalid.invalid> wrote: >>>>>>>>>>>>>>>>>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qsnim$15pr5$1@dont-email.me... >>>>>>>>>>>>>>>>>>> On 5/04/2026 12:37 pm, john larkin wrote: >>>>>>>>>>>>>>>>>>>> On Sun, 5 Apr 2026 12:24:42 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>>>>>>>>>>>>>> wrote: >>>>>>>>>>>>>>>>>>>>> On 5/04/2026 11:07 am, john larkin wrote: >>>>>>>>>>>>>>>>>>>>>> On Thu, 02 Apr 2026 13:56:47 -0700, john larkin <jl@glen--canyon.com> >>>>>>>>>>>>>>>>>>>>>> wrote: >>>>>>>>>> >>>>>>>>>> <snip> >>>>>>>>>> >>>>>>>>>>>>> What's hard to understand about two or more LXZ1-PB01 LEDs? >>>>>>>>>>>>> 12V isn't hard to find. >>>>>>>>>>>> >>>>>>>>>>>> Nobody who actually wanted to use the circuit would talk about "two or more LXZ1-PB01 LEDs". >>>>>>>>>>> >>>>>>>>>>> Diodes tend to fail short. I have no information on the extent to which these LEDs fail short but >>>>>>>>>>> do you want the others to die quicker or continue working normally? >>>>>>>>>> >>>>>>>>>> The circuit is a constant current driver. If enough LEDS fail short you might end up dissipating enough power in the >>>>>>>>>> driver >>>>>>>>>> to >>>>>>>>>> blow it up too, but until that happened the surviving LEDs will see exactly the same current as they did before the other >>>>>>>>>> LEDs >>>>>>>>>> failed. >>>>>>>>> >>>>>>>>> Thank you for your input, I will modify the specification as follows: >>>>>>>>> >>>>>>>>> Drive 500 mA +/- 50mA constant current though a string of 1,2,3 or 4 LXZ1-PB01 LEDs >>>>>>>>> In the case of 0 LEDs (short circuit) no damage should occur and the current may be 500mA or lower. >>>>>>>>> Cathode connection to LEDs should be grounded. >>>>>>>>> Anode connection should be filtered as necessary so as to comply with CISPR 22 Class B. >>>>>>>>> Input 12 - 15 V DC. >>>>>>>>> High efficiency and low cost is required, depending on what can be achieved, >>>>>>>>> so there is currently no exact target for efficiency or cost. >>>>>>>> >>>>>>>> The EDN circuit specified BC557B and BC550B transistors >>>>>>>> >>>>>>>> https://www.onsemi.com/download/data-sheet/pdf/bc556b-d.pdf >>>>>>>> specifies an maximum continous current of 100mA, peak 200m >>>>>>>> >>>>>>>> https://www.onsemi.com/download/data-sheet/pdf/bc550-d.pdf >>>>>>>> specifies an maximum current of 100mA. >>>>>>>> >>>>>>>> They won't meet your specification. >>>>>>>> >>>>>>>>> Let me know when you have met this specification. >>>>>>>> >>>>>>>> Since the specification is nonsense in the context of this thread, I'm obviously not going to take it seriously. >>>>>>>> >>>>>>>>> Your design need not, of course, be anything like the design I posted. >>>>>>>> >>>>>>>> If you can't get the current levels right there's not a lot of point in looking at your "design'. I haven't done so because >>>>>>>> I >>>>>>>> don't take you all that seriously. >>>>>>> >>>>>>>In other words you're not able to meet my specification which clearly requires more >>>>>>>current than the EDN circuit. >>>>>>> >>>>>> >>>>>> Take a look at the cute little TI switchers, like TPS562208. Simple, >>>>>> spread-spectrum, cheap. We pay 21 cents for that one. There are higher >>>>>> voltage parts in the family. >>>>>> >>>>>> I think one could design a switchmode 500 mA LED current limiter with >>>>>> that chip and maybe 5 cheap passives. >>>>> >>>>>Do any similar parts exist which have LTSpice models? >>>>> >>>>>> >>>>>> >>>>>> John Larkin >>>>>> Highland Tech Glen Canyon Design Center >>>>>> Lunatic Fringe Electronics >>>>> >>>> >>>> TI has Pspice models of many of their parts. I don't have much luck >>>> importing them into LT Spice, but I know that it can be done. >>>> >>>> I'd like to find someone to do that for me now and then, pick up >>>> something like the TPS chip and deliver a working LT sim. >>> >>> I got TPS54302.LIB and made a symbol. The pin names don't match but presumably PH is SW >>> and VSENSE is FB. >>> >>> I then tried to make Fig 7-1 in the data sheet but although it runs it does not so far do anything useful. >> >>News just in. The alternate solver produces 5V at 3A into 1.7 ohm. Switching looks fine. >> >>> > > Be careful - LTSpice can have lots of problems with pspice syntax > which are not always apparent. Simulations can appear to run but in > fact generate bollocks. LTSpice 26 is a great improvment over earlier > versions in this regard. Attached is a TPS562208 sim - it looks OK in > 26, but will run incorrectly in 25. > > https://mega.nz/file/g8EVHD7Z#4MDojAygdgfvhsauUKhFyutfCrkK3Q-_EHpxWMNtT2o Ok thanks for that. I have 26.0.1 > > -- > This email has been checked for viruses by Avast antivirus software. > www.avast.com
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| From | "Edward Rawde" <invalid@invalid.invalid> |
|---|---|
| Date | 2026-04-05 22:16 -0400 |
| Message-ID | <10qv52c$cuq$1@nnrp.usenet.blueworldhosting.com> |
| In reply to | #742738 |
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qu4d1$1hgp3$3@dont-email.me... > On 5/04/2026 6:57 pm, john larkin wrote: >> On Sun, 5 Apr 2026 01:10:08 -0400, "Edward Rawde" >> <invalid@invalid.invalid> wrote: >> >>> "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qsnim$15pr5$1@dont-email.me... >>>> On 5/04/2026 12:37 pm, john larkin wrote: >>>>> On Sun, 5 Apr 2026 12:24:42 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote: >>>>> >>>>>> On 5/04/2026 11:07 am, john larkin wrote: >>>>>>> On Thu, 02 Apr 2026 13:56:47 -0700, john larkin <jl@glen--canyon.com> >>>>>>> wrote: > > <snip> > >> Let's see Bill's circuit next. > > You needed find somebody silly enough to take this nonsense seriously. Edward Rawde is apparently willing to play with you. I'm > happy to leave you in his capable hands. The specification is as follows. Drive 500 mA +/- 50mA constant current though a string of 1,2,3 or 4 LXZ1-PB01 LEDs Cathode connection to LEDs should be grounded. Anode connection should be filtered as necessary so as to comply with CISPR 22 Class B. Input 12 - 15 V DC. High efficiency and low cost is required, depending on what can be achieved, so there is currently no exact target for efficiency or cost. > > -- > Bill Sloman, Sydney > >
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| From | piglet <erichpwagner@hotmail.com> |
|---|---|
| Date | 2026-04-05 22:27 +0100 |
| Message-ID | <10quk40$1locs$1@dont-email.me> |
| In reply to | #742718 |
On 05/04/2026 6:10 am, Edward Rawde wrote: > "Bill Sloman" <bill.sloman@ieee.org> wrote in message news:10qsnim$15pr5$1@dont-email.me... >> On 5/04/2026 12:37 pm, john larkin wrote: >>> On Sun, 5 Apr 2026 12:24:42 +1000, Bill Sloman <bill.sloman@ieee.org> >>> wrote: >>> >>>> On 5/04/2026 11:07 am, john larkin wrote: >>>>> On Thu, 02 Apr 2026 13:56:47 -0700, john larkin <jl@glen--canyon.com> >>>>> wrote: >>>>> >>>>>> >>>>>> https://www.edn.com/a-fully-floating-bjt-based-led-current-driver/ >>>>>> >>>>>> Why does it even start? >>>>>> >>>>>> Why not use a cc diode or a depletion fet? >>>> >>>>> That circuit may be very inefficient, depending on the LEDs and the >>>>> input voItage range, and could fry those dinky little transistors. It >>>>> should be a switcher. That could be done with 4 or 5 parts for about >>>>> 35 cents. >>>> >>>> EDN doesn't specify the transistors at all. >>> >>> ?????? >>> >>> It sure does, in plain sight. Silly little TO-92s. >> >> Oops. My mistake. Also EDNs. They didn't specify the LEDs to be driven, or with what current so specifying specific transistors >> was a mistake. >>> >>>> They don't have to be dinky. >>> >>> No, but they are. >>> >>>> A practical design couldn't start until the nature and number of LEDs >>>> being driven had been specified. If the designer was remarkably >>>> incompetent they could put together something that might fry the >>>> transistors. Since John Larkin may select his staff on their willingness >>>> to flatter him it might happen. None of the people I've worked with have >>>> ever been that silly - they made less obvious mistakes. >>> >>> Conservation of energy requires that the circuit dissipate >>> I*(Vsupply-Vled)... unless you use a switcher. >> >> So what? >> >>>>> It wouldn't be a constant-current block of course; constant-power. >>>> >>>> Why? You could do either. What you want from LEDs is constant >>>> brightness, which equates to constant current. The voltage drop across a >>>> LED isn't linearly dependent on the current through them, so that does >>>> come pretty close to constant power. >>> >>> A switcher would be constant power in and constant current out. And >>> very efficient. >> >> It might be. Switching losses are real, and inept design can make them quite large. >> >>> Give it a try. >> >> Specify the LEDs you want to drive, and the current you want to drive them at, and I might. Without that information the problem >> is undefined and perfectly insoluble. Since you wouldn't build the device, it would a waste of effort even if you produced a >> specification of what you wanted. >> >> -- >> Bill Sloman, Sydney > > Ok please make an equivalent of this but to your design standards and low cost. > Note that I'm not asking for criticism of this circuit. There are many reasons why > reality may not be the same as its simulation but I had fun doing it. > If it doesn't give a constant current of 500mA, open it in Notepad++ > Under Encoding, convert to ANSI and save it. > > Version 4.1 > SHEET 1 2820 680 > WIRE 976 -128 272 -128 > WIRE 1072 -128 1040 -128 > WIRE 16 -48 -16 -48 > WIRE 96 -48 16 -48 > WIRE 240 -48 96 -48 > WIRE 336 -48 240 -48 > WIRE 448 -48 336 -48 > WIRE 464 -48 448 -48 > WIRE 528 -48 464 -48 > WIRE 608 -48 528 -48 > WIRE 672 -48 608 -48 > WIRE 784 -48 768 -48 > WIRE 816 -48 784 -48 > WIRE 864 -48 816 -48 > WIRE 992 -48 944 -48 > WIRE 1024 -48 992 -48 > WIRE 1072 -48 1072 -128 > WIRE 1072 -48 1024 -48 > WIRE 1264 -48 1072 -48 > WIRE 1360 -48 1264 -48 > WIRE 240 -16 240 -48 > WIRE 336 -16 336 -48 > WIRE 1264 0 1264 -48 > WIRE 1360 0 1360 -48 > WIRE -16 32 -16 -48 > WIRE 608 32 608 -48 > WIRE 1168 32 608 32 > WIRE 448 64 448 -48 > WIRE 464 64 464 -48 > WIRE 96 80 96 -48 > WIRE 240 80 240 64 > WIRE 272 80 272 -128 > WIRE 272 80 240 80 > WIRE 336 80 336 64 > WIRE 384 80 336 80 > WIRE 416 80 384 80 > WIRE 816 80 816 -48 > WIRE 992 80 992 -48 > WIRE 1168 80 1168 32 > WIRE 336 96 336 80 > WIRE 336 96 304 96 > WIRE 656 96 480 96 > WIRE 688 96 688 0 > WIRE 688 96 656 96 > WIRE 1232 96 1200 96 > WIRE 1264 96 1264 64 > WIRE 1264 96 1232 96 > WIRE 240 112 240 80 > WIRE 384 112 240 112 > WIRE 416 112 384 112 > WIRE 528 112 528 -48 > WIRE 608 112 608 32 > WIRE 1104 112 1088 112 > WIRE 1136 112 1104 112 > WIRE 240 128 240 112 > WIRE 336 128 336 96 > WIRE 1312 128 1200 128 > WIRE 1360 128 1360 80 > WIRE 1360 128 1312 128 > WIRE 1360 160 1360 128 > WIRE -16 176 -16 112 > WIRE 240 240 240 208 > WIRE 336 240 336 208 > WIRE 336 240 240 240 > WIRE 384 240 336 240 > WIRE 432 240 432 128 > WIRE 432 240 384 240 > WIRE 448 240 448 128 > WIRE 448 240 432 240 > WIRE 464 240 464 128 > WIRE 464 240 448 240 > WIRE 528 240 528 176 > WIRE 528 240 464 240 > WIRE 544 240 528 240 > WIRE 608 240 608 176 > WIRE 608 240 544 240 > WIRE 1360 240 1360 224 > WIRE 1424 240 1360 240 > WIRE 1536 240 1424 240 > WIRE 1696 240 1600 240 > WIRE 1872 240 1760 240 > WIRE 544 272 544 240 > WIRE 1264 272 1264 96 > WIRE 1360 272 1360 240 > WIRE -16 368 -16 256 > WIRE 96 368 96 144 > WIRE 96 368 -16 368 > WIRE 544 368 544 352 > WIRE 544 368 96 368 > WIRE 816 368 816 144 > WIRE 816 368 544 368 > WIRE 992 368 992 144 > WIRE 992 368 816 368 > WIRE 1168 368 1168 144 > WIRE 1168 368 992 368 > WIRE 1264 368 1264 352 > WIRE 1264 368 1168 368 > WIRE 1360 368 1360 336 > WIRE 1360 368 1264 368 > WIRE 1872 368 1872 240 > WIRE 1872 368 1360 368 > WIRE -16 384 -16 368 > WIRE 304 448 304 96 > WIRE 992 448 304 448 > WIRE 1088 448 1088 112 > WIRE 1088 448 1072 448 > FLAG -16 384 0 > FLAG 16 -48 in > FLAG 784 -48 sw > FLAG 1024 -48 out > FLAG 1312 128 isense > FLAG 1232 96 iref > FLAG 1104 112 ifb > FLAG 384 80 cmp- > FLAG 384 112 cmp+ > FLAG 656 96 gate > FLAG 384 240 cmpv- > FLAG 1424 240 led > SYMBOL Comparators\\LT1719 448 32 R0 > WINDOW 0 27 27 Left 2 > WINDOW 3 -92 6 Left 2 > SYMATTR InstName U1 > SYMBOL res 320 112 R0 > WINDOW 0 41 34 Left 2 > WINDOW 3 35 64 Left 2 > SYMATTR InstName R4 > SYMATTR Value 10K > SYMATTR SpiceLine tol=1 pwr=0.1 > SYMBOL ind 960 -64 R90 > WINDOW 0 63 51 VBottom 2 > WINDOW 3 -27 53 VTop 2 > SYMATTR InstName L1 > SYMATTR Value 0.068m > SYMATTR SpiceLine Ipk=0.85 Rser=0.21 Rpar=0 Cpar=0 > SYMBOL res 1376 -16 M0 > WINDOW 0 -37 34 Left 2 > WINDOW 3 -57 63 Left 2 > SYMATTR InstName R8 > SYMATTR Value 0.68 > SYMATTR SpiceLine tol=1 pwr=0.1 > SYMBOL res 224 -32 R0 > WINDOW 0 -35 19 Left 2 > WINDOW 3 -49 48 Left 2 > SYMATTR InstName R1 > SYMATTR Value 10K > SYMATTR SpiceLine tol=1 pwr=0.1 > SYMBOL schottky 832 144 R180 > WINDOW 0 -42 30 Left 2 > WINDOW 3 -119 -3 Left 2 > SYMATTR InstName D2 > SYMATTR Value MBRS130L > SYMATTR Description Diode > SYMATTR Type diode > SYMBOL pmos 768 0 M270 > WINDOW 0 10 129 VLeft 2 > WINDOW 3 -10 67 VLeft 2 > SYMATTR InstName M1 > SYMATTR Value AO6407 > SYMBOL voltage -16 160 R0 > WINDOW 0 -75 16 Left 2 > WINDOW 3 -71 54 Left 2 > WINDOW 123 0 0 Left 0 > WINDOW 39 -185 81 Left 2 > SYMATTR InstName V3 > SYMATTR Value 12 > SYMBOL res -32 16 R0 > WINDOW 0 -39 29 Left 2 > WINDOW 3 -63 65 Left 2 > SYMATTR InstName R9 > SYMATTR Value 0.001 > SYMBOL zener 544 176 R180 > WINDOW 0 37 29 Left 2 > WINDOW 3 78 -5 Right 2 > SYMATTR InstName D1 > SYMATTR Value BZX84C6V2L > SYMBOL res 320 -32 R0 > WINDOW 0 40 7 Left 2 > WINDOW 3 37 33 Left 2 > SYMATTR InstName R3 > SYMATTR Value 10K > SYMATTR SpiceLine tol=1 pwr=0.1 > SYMBOL res 528 368 M180 > WINDOW 0 39 76 Left 2 > WINDOW 3 38 42 Left 2 > SYMATTR InstName R5 > SYMATTR Value 220 > SYMATTR SpiceLine tol=1 pwr=0.25 > SYMBOL cap 592 176 M180 > WINDOW 0 29 52 Left 2 > WINDOW 3 30 13 Left 2 > SYMATTR InstName C3 > SYMATTR Value 100n > SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.0337 Lser=180p mfg="Würth Elektronik" pn="885012104009 WCAP-CSGP 0201" type="X5R" > SYMBOL polcap 976 80 R0 > WINDOW 3 -11 59 Left 2 > WINDOW 0 27 9 Left 2 > SYMATTR Value 100000n > SYMATTR InstName C1 > SYMATTR Description Capacitor > SYMATTR Type cap > SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.9 Lser=0 mfg="AVX" pn="TAJD107M006" type="Tantalum" > SYMBOL res 224 112 R0 > WINDOW 0 -40 33 Left 2 > WINDOW 3 -52 57 Left 2 > SYMATTR InstName R2 > SYMATTR Value 10K > SYMATTR SpiceLine tol=1 pwr=0.1 > SYMBOL polcap 80 80 R0 > WINDOW 3 -27 60 Left 2 > WINDOW 0 -39 4 Left 2 > SYMATTR Value 100000n > SYMATTR InstName C2 > SYMATTR Description Capacitor > SYMATTR Type cap > SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.9 Lser=0 mfg="AVX" pn="TAJD107M006" type="Tantalum" > SYMBOL LED 1536 256 R270 > WINDOW 0 72 32 VTop 2 > WINDOW 3 0 32 VBottom 2 > SYMATTR InstName LED1 > SYMATTR Value LXZ1-PB01 > SYMBOL res 976 432 M90 > WINDOW 0 -2 59 VBottom 2 > WINDOW 3 35 64 VTop 2 > SYMATTR InstName R6 > SYMATTR Value 22K > SYMATTR SpiceLine tol=1 pwr=0.1 > SYMBOL cap 976 -144 M90 > WINDOW 0 -3 31 VBottom 2 > WINDOW 3 36 35 VTop 2 > SYMATTR InstName C5 > SYMATTR Value 10n > SYMATTR SpiceLine V=16 Irms=0 Rser=0.0747 Lser=525p mfg="Würth Elektronik" pn="885012210001 WCAP-CSGP 1812" type="X7R" > SYMBOL OpAmps\\OP07 1168 48 M0 > WINDOW 0 12 22 Left 2 > WINDOW 3 9 103 Left 2 > SYMATTR InstName U2 > SYMBOL res 1248 368 M180 > WINDOW 0 -40 81 Left 2 > WINDOW 3 -51 46 Left 2 > SYMATTR InstName R7 > SYMATTR Value 470 > SYMATTR SpiceLine tol=1 pwr=0.1 > SYMBOL schottky 1280 0 M0 > WINDOW 0 43 24 Left 2 > WINDOW 3 40 -8 Left 2 > SYMATTR InstName D3 > SYMATTR Value BAT54AHY > SYMATTR Description Diode > SYMATTR Type diode > SYMBOL FerriteBead 1360 192 R0 > SYMATTR InstName L2 > SYMATTR Value 6µ > SYMATTR SpiceLine Ipk=3 Rser=0.0102 Rpar=1220 Cpar=1.9p > SYMBOL cap 1344 272 R0 > SYMATTR InstName C4 > SYMATTR Value 1n > SYMATTR SpiceLine V=10 Irms=0 Rser=0.1909 Lser=177p mfg="Würth Elektronik" pn="885012205006 WCAP-CSGP 0402" type="X7R" > SYMBOL LED 1696 256 R270 > WINDOW 0 72 32 VTop 2 > WINDOW 3 0 32 VBottom 2 > SYMATTR InstName LED2 > SYMATTR Value LXZ1-PB01 > TEXT -24 440 Left 2 !.tran 0 0.001 0 1u startup > TEXT -24 480 Left 2 !.options plotwinsize=0 > > To light LEDs you can probably do without ICs or even capacitors, here is an almost-two-terminal very cheap and dirty switcher idea ... <https://www.dropbox.com/scl/fi/4w3k0rvr5g7up8occfsjj/Buck_Hysteretic.jpeg?rlkey=bb2nlbzyzprxrzegb9wfddem4&st=n3btk1il&raw=1> piglet
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| From | someone <2a59d59e3809f827ce709d3815e3950eef4a6a93af5557a93a7fdfba71460843@example.com> |
|---|---|
| Date | 2026-04-09 03:45 +0000 |
| Message-ID | <18a493794d041b26$1$2982030$4226dc73@news.newsgroupdirect.com> |
| In reply to | #742648 |
If you stand back from the microscopic current mirror circuit interpretation, the transistor equivalent of the DIAC using Q2,4,3, with a threshold of 2.5V or so, comes into focus. Then add in some current limiting/ regulating resistors here and there, and you end up with the floating current source. The BC557C has an absurdly small Early voltage and RCE, combined with the 'C' version beta in the range of 200-800, and start-up is a done deal. Voltage compliance shouldn't be a serious issue for driving LEDs, but it would be nice to see an analytic to that effect. AI hasn't penetrated deeply enough into our freebie CADs to give us that capabilty, so we're stuck with looking at graphs. -- For full context, visit https://www.electrondepot.com/electrodesign/silly-circuit-4400338-.htm
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| From | "Don" <g@crcomp.net> |
|---|---|
| Date | 2026-04-09 09:17 +0000 |
| Subject | A fully floating BJT-based LED current driver |
| Message-ID | <20260409a@crcomp.net> |
| In reply to | #742842 |
someone wrote:
> If you stand back from the microscopic current mirror circuit
> interpretation, the transistor equivalent of the DIAC using Q2,4,3,
> with a threshold of 2.5V or so, comes into focus. Then add in some
> current limiting/ regulating resistors here and there, and you end
> up with the floating current source. The BC557C has an absurdly
> small Early voltage and RCE, combined with the 'C' version beta in
> the range of 200-800, and start-up is a done deal. Voltage compliance
> shouldn't be a serious issue for driving LEDs, but it would be nice
> to see an analytic to that effect. AI hasn't penetrated deeply enough
> into our freebie CADs to give us that capabilty, so we're stuck with
> looking at graphs.
Excellent! Your circuit suggests some silicon secrets pertinent to the
120 VAC LED COB filaments mentioned by me elsewhere:
Allow me to transition this topic to 120 VAC LED COB filaments. This
picture shows such specimens, with the topmost powered-on and the
bottommost powered-off:
<https://crcomp.net/led/accob.png>
The protoboard's black wire connects to 120 ACV Line while its white
wire connects to Neutral. My goal is to discover the silicon secrets
in such a simple filament.
--
73, Don, KB7RPU veritas _|_
liberabit |
https://www.qsl.net/kb7rpu vos |
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| From | JM <sunaecoNoChoppedPork@gmail.com> |
|---|---|
| Date | 2026-04-09 16:16 +0100 |
| Subject | Re: A fully floating BJT-based LED current driver |
| Message-ID | <vjgftk1k5t0ukin3sftgfp9mjpqgtbegkk@4ax.com> |
| In reply to | #742846 |
On Thu, 9 Apr 2026 09:17:04 -0000 (UTC), "Don" <g@crcomp.net> wrote: >Allow me to transition this topic to 120 VAC LED COB filaments. This >picture shows such specimens, with the topmost powered-on and the >bottommost powered-off: > > <https://crcomp.net/led/accob.png> > >The protoboard's black wire connects to 120 ACV Line while its white >wire connects to Neutral. My goal is to discover the silicon secrets >in such a simple filament. Look up NUD4011 and it's alternatives, it'll be something that operates in a similar fashion. -- This email has been checked for viruses by Avast antivirus software. www.avast.com
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| From | "Don" <g@crcomp.net> |
|---|---|
| Date | 2026-04-09 22:03 +0000 |
| Subject | Re: A fully floating BJT-based LED current driver |
| Message-ID | <20260409b@crcomp.net> |
| In reply to | #742850 |
JM <sunaecoNoChoppedPork@gmail.com> wrote:
> On Thu, 9 Apr 2026 09:17:04 -0000 (UTC), "Don" <g@crcomp.net> wrote:
>
>>Allow me to transition this topic to 120 VAC LED COB filaments. This
>>picture shows such specimens, with the topmost powered-on and the
>>bottommost powered-off:
>>
>> <https://crcomp.net/led/accob.png>
>>
>>The protoboard's black wire connects to 120 ACV Line while its white
>>wire connects to Neutral. My goal is to discover the silicon secrets
>>in such a simple filament.
>
> Look up NUD4011 and it's alternatives, it'll be something that
> operates in a similar fashion.
Thank you.
--
73, Don, KB7RPU veritas _|_
liberabit |
https://www.qsl.net/kb7rpu vos |
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| From | john larkin <jl@glen--canyon.com> |
|---|---|
| Date | 2026-04-09 16:46 -0700 |
| Subject | Re: A fully floating BJT-based LED current driver |
| Message-ID | <5sdgtkl2jcbqq1l28a90742i1d4dbkdb7t@4ax.com> |
| In reply to | #742850 |
On Thu, 09 Apr 2026 16:16:34 +0100, JM <sunaecoNoChoppedPork@gmail.com> wrote: >On Thu, 9 Apr 2026 09:17:04 -0000 (UTC), "Don" <g@crcomp.net> wrote: > >>Allow me to transition this topic to 120 VAC LED COB filaments. This >>picture shows such specimens, with the topmost powered-on and the >>bottommost powered-off: >> >> <https://crcomp.net/led/accob.png> >> >>The protoboard's black wire connects to 120 ACV Line while its white >>wire connects to Neutral. My goal is to discover the silicon secrets >>in such a simple filament. > >Look up NUD4011 and it's alternatives, it'll be something that >operates in a similar fashion. That would need the NUD chip and a bridge rectifier and maybe a resistor and a varistor. I'd expect simpler and cheaper in that tiny gadget. What do you call that axial lead LED thing? John Larkin Highland Tech Glen Canyon Design Center Lunatic Fringe Electronics
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