Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > sci.electronics.design > #460255 > unrolled thread
| Started by | bitrex <bitrex@de.lete.earthlink.net> |
|---|---|
| First post | 2017-05-14 13:50 -0400 |
| Last post | 2017-05-16 14:05 +0000 |
| Articles | 20 on this page of 134 — 16 participants |
Back to article view | Back to sci.electronics.design
Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 13:50 -0400
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 11:27 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-14 19:19 +0000
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 15:24 -0400
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 12:54 -0700
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:02 -0400
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 13:10 -0700
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:16 -0400
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:18 -0400
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 14:14 -0700
Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-15 19:51 +0100
Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 13:17 -0700
Re: Fast buffer idea Clifford Heath <clifford.heath@gmail.com> - 2017-05-17 09:14 +1000
Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 16:26 -0700
Re: Fast buffer idea "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-05-17 02:04 -0500
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-14 20:26 +0000
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:31 -0400
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:43 -0400
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 14:17 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-14 21:53 +0000
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 16:14 -0700
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 19:59 -0400
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 20:06 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 00:16 +0000
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 20:10 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 03:28 +0000
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 20:48 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 04:17 +0000
Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 07:56 +0000
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 06:58 -0400
Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 12:59 +0000
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-15 07:01 -0700
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 10:09 -0400
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 10:18 -0400
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-15 08:56 -0700
Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 16:02 +0000
Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 10:33 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 18:15 +0000
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 14:25 -0400
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 14:26 -0400
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 16:24 +0000
Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 16:36 +0000
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 17:18 +0000
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 13:30 -0400
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 18:07 +0000
Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 19:19 +0000
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 19:45 +0000
Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-16 08:33 +0000
Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 19:13 +0000
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 15:33 -0400
Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-16 08:16 +0000
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-16 22:10 -0400
Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 19:10 +0000
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-15 08:55 -0700
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 12:51 -0400
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 12:56 -0400
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 13:05 -0400
Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 10:28 -0700
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 13:38 -0400
Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 11:29 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 18:41 +0000
Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 13:19 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 20:46 +0000
Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 13:56 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 21:00 +0000
Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 16:46 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-16 01:22 +0000
Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 11:16 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-16 18:55 +0000
Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 12:21 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-16 20:33 +0000
Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 14:00 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-16 21:21 +0000
Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 16:15 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-16 23:58 +0000
Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 17:51 -0700
Re: Fast buffer idea pcdhobbs@gmail.com - 2017-05-16 16:30 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-17 00:16 +0000
Re: Fast buffer idea pcdhobbs@gmail.com - 2017-05-16 18:05 -0700
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-16 20:05 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-25 01:13 +0000
Re: Fast buffer idea Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-05-24 21:43 -0400
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-30 03:16 +0000
Re: Fast buffer idea Ralph Barone <ralph@invalid.com> - 2017-05-17 02:26 +0000
Re: Fast buffer idea Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-17 08:34 +0200
Re: Fast buffer idea Ralph Barone <ralph@invalid.com> - 2017-05-17 14:31 +0000
Re: Fast buffer idea Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-05-17 10:39 -0400
Re: Fast buffer idea Reinhardt Behm <rbehm@hushmail.com> - 2017-05-17 23:02 +0800
Re: Fast buffer idea Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-16 21:24 +0200
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-16 20:12 -0700
Re: Fast buffer idea Winfield Hill <hill@rowland.harvard.edu> - 2017-05-25 04:38 -0700
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-25 07:28 -0700
Re: Fast buffer idea "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-05-26 08:54 -0500
Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-26 14:14 +0000
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-26 07:21 -0700
Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-16 20:27 +0100
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 15:05 -0400
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 15:19 -0400
Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 13:21 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 20:56 +0000
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 17:37 -0400
Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-15 19:50 +0100
Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 19:25 +0000
Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-16 20:19 +0100
Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 14:33 +0000
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 13:15 -0400
Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 19:05 +0000
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 15:38 -0400
Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-16 08:12 +0000
Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-16 18:47 +0000
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-16 21:52 -0400
Re: Fast buffer idea Winfield Hill <hill@rowland.harvard.edu> - 2017-05-25 05:05 -0700
Re: Fast buffer idea pcdhobbs@gmail.com - 2017-05-25 05:42 -0700
Re: Fast buffer idea Winfield Hill <hill@rowland.harvard.edu> - 2017-05-25 05:49 -0700
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-25 08:10 -0700
Re: Fast buffer idea Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-25 15:01 +0200
Re: Fast buffer idea "John Miles, KE5FX" <jmiles@gmail.com> - 2017-05-14 18:53 -0700
Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 02:45 +0000
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 15:23 -0400
Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-14 20:28 +0100
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:00 -0400
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:10 -0400
Re: Fast buffer idea Winfield Hill <hill@rowland.harvard.edu> - 2017-05-14 17:58 -0700
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 23:13 -0400
Re: Fast buffer idea Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-05-16 17:27 -0700
Re: Fast buffer idea Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-05-16 17:34 -0700
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 20:14 -0700
Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-15 19:42 +0100
Re: Fast buffer idea "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-05-16 03:29 -0500
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-16 06:57 -0700
Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-16 22:47 -0400
Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-16 20:18 -0700
Re: Fast buffer idea "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-05-17 02:22 -0500
Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-16 14:05 +0000
Page 3 of 7 — ← Prev page 1 2 [3] 4 5 6 7 Next page →
| From | Steve Wilson <no@spam.com> |
|---|---|
| Date | 2017-05-15 16:24 +0000 |
| Message-ID | <XnsA7767E5052407idtokenpost@69.16.179.22> |
| In reply to | #460343 |
bitrex <bitrex@de.lete.earthlink.net> wrote: > On 05/15/2017 10:09 AM, bitrex wrote: >> On 05/15/2017 10:01 AM, John Larkin wrote: >> >>> BW is 230 MHz as a unity-gain buffer. Each half of the dual will >>> source and sink 88 mA. And there are lots of faster THS-series parts. >>> >>>> >>>> But indeed you can do that with a few NPNs of the old days, >>>> >>> >>> Post it. >> >> With discretes you can have: >> >> 1) wide bandwidth >> >> 2) low parts count >> >> 3) low quiescent current draw >> >> Pick two. > > The two transistor circuit Jan posted does have a pretty wide bandwidth > and a low parts count. It has a pretty nice small signal output > impedance, but its large-signal output impedance is bad. It also draws a > relatively large amount of quiescent current. I somehow missed the two transistor circuit that Jan posted. Can you please repost the link? Thanks
[toc] | [prev] | [next] | [standalone]
| From | Jan Panteltje <pNa0nStpealmtje@yahoo.com> |
|---|---|
| Date | 2017-05-15 16:36 +0000 |
| Message-ID | <ofcldu$n1m$1@gioia.aioe.org> |
| In reply to | #460364 |
On a sunny day (Mon, 15 May 2017 16:24:56 GMT) it happened Steve Wilson <no@spam.com> wrote in <XnsA7767E5052407idtokenpost@69.16.179.22>: >bitrex <bitrex@de.lete.earthlink.net> wrote: > >> On 05/15/2017 10:09 AM, bitrex wrote: >>> On 05/15/2017 10:01 AM, John Larkin wrote: >>> >>>> BW is 230 MHz as a unity-gain buffer. Each half of the dual will >>>> source and sink 88 mA. And there are lots of faster THS-series parts. >>>> >>>>> >>>>> But indeed you can do that with a few NPNs of the old days, >>>>> >>>> >>>> Post it. >>> >>> With discretes you can have: >>> >>> 1) wide bandwidth >>> >>> 2) low parts count >>> >>> 3) low quiescent current draw >>> >>> Pick two. >> >> The two transistor circuit Jan posted does have a pretty wide bandwidth >> and a low parts count. It has a pretty nice small signal output >> impedance, but its large-signal output impedance is bad. It also draws >a >> relatively large amount of quiescent current. > >I somehow missed the two transistor circuit that Jan posted. Can you >please repost the link? > >Thanks From: http://panteltje.com/panteltje/quadcopter/hud.html the circuit diagram: http://panteltje.com/panteltje/quadcopter/hud-0.1_circuit_diagram_IMG_5984.JPG bottom left: that has a gain of 2, so can drive a 75 Ohm cable with reasonable Zi. The DC path requires an other 75 Ohm at the end of the cable.
[toc] | [prev] | [next] | [standalone]
| From | Steve Wilson <no@spam.com> |
|---|---|
| Date | 2017-05-15 17:18 +0000 |
| Message-ID | <XnsA776875EB8A7idtokenpost@69.16.179.23> |
| In reply to | #460367 |
Jan Panteltje <pNa0nStpealmtje@yahoo.com> wrote: > On a sunny day (Mon, 15 May 2017 16:24:56 GMT) it happened Steve > Wilson <no@spam.com> wrote in > <XnsA7767E5052407idtokenpost@69.16.179.22>: > >>bitrex <bitrex@de.lete.earthlink.net> wrote: >> >>> On 05/15/2017 10:09 AM, bitrex wrote: >>>> On 05/15/2017 10:01 AM, John Larkin wrote: >>>> >>>>> BW is 230 MHz as a unity-gain buffer. Each half of the dual will >>>>> source and sink 88 mA. And there are lots of faster THS-series >>>>> parts. >>>>> >>>>>> >>>>>> But indeed you can do that with a few NPNs of the old days, >>>>>> >>>>> >>>>> Post it. >>>> >>>> With discretes you can have: >>>> >>>> 1) wide bandwidth >>>> >>>> 2) low parts count >>>> >>>> 3) low quiescent current draw >>>> >>>> Pick two. >>> >>> The two transistor circuit Jan posted does have a pretty wide >>> bandwidth and a low parts count. It has a pretty nice small signal >>> output impedance, but its large-signal output impedance is bad. It >>> also draws a relatively large amount of quiescent current. >> >>I somehow missed the two transistor circuit that Jan posted. Can you >>please repost the link? >> >>Thanks > > From: > http://panteltje.com/panteltje/quadcopter/hud.html > the circuit diagram: > http://panteltje.com/panteltje/quadcopter/hud-0.1_circuit_diagram_IMG > _5984.JPG bottom left: > that has a gain of 2, so can drive a 75 Ohm cable with reasonable Zi. > The DC path requires an other 75 Ohm at the end of the cable. OK, thanks. That is a Sziklai Pair with a voltage divider in the feedback path: https://en.wikipedia.org/wiki/Sziklai_pair It would normally have the same thermal drift as a simple base-emitter junction, but the divide by two may increase it. The output impedance may be increased due to the low loop gain. The bandwidth is determined by the transistors you use. But it is difficult to tell what the transistors are due to the poor clarity of the handwritten numbers. I can't read them even when I expand the drawing. I really wish you could convert some of your critical circuits to LTspice so we can see the operation a bit better. That would have a far greater impact for the value of your work.
[toc] | [prev] | [next] | [standalone]
| From | bitrex <bitrex@de.lete.earthlink.net> |
|---|---|
| Date | 2017-05-15 13:30 -0400 |
| Message-ID | <MAlSA.118066$ef.9536@fx34.iad> |
| In reply to | #460376 |
On 05/15/2017 01:18 PM, Steve Wilson wrote: > Jan Panteltje <pNa0nStpealmtje@yahoo.com> wrote: > >> On a sunny day (Mon, 15 May 2017 16:24:56 GMT) it happened Steve >> Wilson <no@spam.com> wrote in >> <XnsA7767E5052407idtokenpost@69.16.179.22>: >> >>> bitrex <bitrex@de.lete.earthlink.net> wrote: >>> >>>> On 05/15/2017 10:09 AM, bitrex wrote: >>>>> On 05/15/2017 10:01 AM, John Larkin wrote: >>>>> >>>>>> BW is 230 MHz as a unity-gain buffer. Each half of the dual will >>>>>> source and sink 88 mA. And there are lots of faster THS-series >>>>>> parts. >>>>>> >>>>>>> >>>>>>> But indeed you can do that with a few NPNs of the old days, >>>>>>> >>>>>> >>>>>> Post it. >>>>> >>>>> With discretes you can have: >>>>> >>>>> 1) wide bandwidth >>>>> >>>>> 2) low parts count >>>>> >>>>> 3) low quiescent current draw >>>>> >>>>> Pick two. >>>> >>>> The two transistor circuit Jan posted does have a pretty wide >>>> bandwidth and a low parts count. It has a pretty nice small signal >>>> output impedance, but its large-signal output impedance is bad. It >>>> also draws a relatively large amount of quiescent current. >>> >>> I somehow missed the two transistor circuit that Jan posted. Can you >>> please repost the link? >>> >>> Thanks >> >> From: >> http://panteltje.com/panteltje/quadcopter/hud.html >> the circuit diagram: >> http://panteltje.com/panteltje/quadcopter/hud-0.1_circuit_diagram_IMG >> _5984.JPG bottom left: >> that has a gain of 2, so can drive a 75 Ohm cable with reasonable Zi. >> The DC path requires an other 75 Ohm at the end of the cable. > > OK, thanks. > > That is a Sziklai Pair with a voltage divider in the feedback path: > > https://en.wikipedia.org/wiki/Sziklai_pair > > It would normally have the same thermal drift as a simple base-emitter > junction, but the divide by two may increase it. > > The output impedance may be increased due to the low loop gain. The > bandwidth is determined by the transistors you use. Its output impedance for large negative-going signals is _dogshit_, regardless of what the small-signal analysis feedback-loop-gain etc. calculations indicate. It can source current okay. It definitely can't sink it. It doesn't really matter for a composite video signal, though, because it's not really that wide a bandwidth signal. The only potentially difficult fast full-level transition I think of would be if you have to go from the "back porch" immediately to "full luminance."
[toc] | [prev] | [next] | [standalone]
| From | Steve Wilson <no@spam.com> |
|---|---|
| Date | 2017-05-15 18:07 +0000 |
| Message-ID | <XnsA7768FC3A2F00idtokenpost@69.16.179.23> |
| In reply to | #460378 |
bitrex <bitrex@de.lete.earthlink.net> wrote: > On 05/15/2017 01:18 PM, Steve Wilson wrote: >> That is a Sziklai Pair with a voltage divider in the feedback path: >> https://en.wikipedia.org/wiki/Sziklai_pair >> The output impedance may be increased due to the low loop gain. The >> bandwidth is determined by the transistors you use. > Its output impedance for large negative-going signals is _dogshit_, > regardless of what the small-signal analysis feedback-loop-gain etc. > calculations indicate. It can source current okay. It definitely can't > sink it. The negative swing depends on the pulldown resistor, same as any single- ended emitter follower. That should be obvious. These issues would be immediately apparent in a proper LTspice analysis. Unfortunately, with some users still devoted to ASCII-art or hand-drawn schematics, it is difficult or impossible to do a reasonable preliminary analysis. The author may have made an incredible blunder in the schematic, or it is impossible to determine the component values in a hand-drawn schematic. Often, you really can't tell if it is worth your time to investigate someone's idea. In most cases, with an ASCII-art or hand-drawn schematic, it is not worth the time to spend any effort on it. The author really doesn't know if it works or not. It could be difficult to detect errors in the posted drawing, since there is no error detection mechanism. But with a working LTspice model, it could be worth investigating. If it runs, it means it follows the author's intent. It depends on who authored it. Unfortunately, many beginners post LTspice circuits that are full of blunders. You can immediately tell their thinking is scrambled beyond hope. This is good information. I simply record their names and ignore anything they post so I don't waste any more of my time.
[toc] | [prev] | [next] | [standalone]
| From | Jan Panteltje <pNa0nStpealmtje@yahoo.com> |
|---|---|
| Date | 2017-05-15 19:19 +0000 |
| Message-ID | <ofcv0v$1a31$1@gioia.aioe.org> |
| In reply to | #460386 |
On a sunny day (Mon, 15 May 2017 18:07:57 GMT) it happened Steve Wilson <no@spam.com> wrote in <XnsA7768FC3A2F00idtokenpost@69.16.179.23>: >bitrex <bitrex@de.lete.earthlink.net> wrote: > >> On 05/15/2017 01:18 PM, Steve Wilson wrote: >>> That is a Sziklai Pair with a voltage divider in the feedback path: > >>> https://en.wikipedia.org/wiki/Sziklai_pair > >>> The output impedance may be increased due to the low loop gain. The >>> bandwidth is determined by the transistors you use. > >> Its output impedance for large negative-going signals is _dogshit_, >> regardless of what the small-signal analysis feedback-loop-gain etc. >> calculations indicate. It can source current okay. It definitely can't >> sink it. > >The negative swing depends on the pulldown resistor, same as any single- >ended emitter follower. That should be obvious. > >These issues would be immediately apparent in a proper LTspice analysis. > >Unfortunately, with some users still devoted to ASCII-art or hand-drawn >schematics, it is difficult or impossible to do a reasonable preliminary >analysis. Man you are way way out in the boonies, I can tell from just a few strokes if it wrks or not, Van Gogh could too. [My]Tronix is art, you are no art knower, just a wall painter using spice as paintbrush. ;-) THIS is why US can no longer send humming beans to space, You live in a virtual world. Its all over. The Matrix has you, no way back. ....
[toc] | [prev] | [next] | [standalone]
| From | Steve Wilson <no@spam.com> |
|---|---|
| Date | 2017-05-15 19:45 +0000 |
| Message-ID | <XnsA776A03A13A6Cidtokenpost@69.16.179.22> |
| In reply to | #460410 |
Jan Panteltje <pNa0nStpealmtje@yahoo.com> wrote: > On a sunny day (Mon, 15 May 2017 18:07:57 GMT) it happened Steve Wilson > <no@spam.com> wrote in <XnsA7768FC3A2F00idtokenpost@69.16.179.23>: >>These issues would be immediately apparent in a proper LTspice analysis. >> >>Unfortunately, with some users still devoted to ASCII-art or hand-drawn >>schematics, it is difficult or impossible to do a reasonable preliminary >>analysis. > > Man you are way way out in the boonies, > > I can tell from just a few strokes if it wrks or not, > Van Gogh could too. > [My]Tronix is art, you are no art knower, just a wall painter using spice > as paintbrush. > ;-) > > THIS is why US can no longer send humming beans to space, > You live in a virtual world. > Its all over. > The Matrix has you, no way back. > .... I am retired, so I am not so interested in hiring new enginers. If I were, I would use LTspice. SPICE has a huge learning curve that goes on forever. If a candidate cannot use LTspice, he is of no use to me. You cannot tell if a circuit will work by looking at it. You have to find a way to analyze it that is faster than pencil and paper. The old hybrid- pi models are useless to see if a circuit is usable. Unfortunately, these are stiil taught in engineering schools. My criteria for hiring a new employee would be to show how they are able to construct simple circuits in LTspice and show how they work. If they cannot do that, they are of very little use to me. Your claim that you can tell if a circuit works by simply looking at it is feeble. You need to prove it works, and LTspice is the best way to start.
[toc] | [prev] | [next] | [standalone]
| From | Jan Panteltje <pNa0nStpealmtje@yahoo.com> |
|---|---|
| Date | 2017-05-16 08:33 +0000 |
| Message-ID | <ofedg8$1c62$1@gioia.aioe.org> |
| In reply to | #460414 |
On a sunny day (Mon, 15 May 2017 19:45:04 GMT) it happened Steve Wilson <no@spam.com> wrote in <XnsA776A03A13A6Cidtokenpost@69.16.179.22>: >Jan Panteltje <pNa0nStpealmtje@yahoo.com> wrote: > >> On a sunny day (Mon, 15 May 2017 18:07:57 GMT) it happened Steve Wilson >> <no@spam.com> wrote in <XnsA7768FC3A2F00idtokenpost@69.16.179.23>: >>>These issues would be immediately apparent in a proper LTspice >analysis. >>> >>>Unfortunately, with some users still devoted to ASCII-art or hand-drawn >>>schematics, it is difficult or impossible to do a reasonable >preliminary >>>analysis. >> >> Man you are way way out in the boonies, >> >> I can tell from just a few strokes if it wrks or not, >> Van Gogh could too. >> [My]Tronix is art, you are no art knower, just a wall painter using >spice >> as paintbrush. >> ;-) >> >> THIS is why US can no longer send humming beans to space, >> You live in a virtual world. >> Its all over. >> The Matrix has you, no way back. >> .... > >I am retired, so I am not so interested in hiring new enginers. If I >were, I would use LTspice. SPICE has a huge learning curve that goes on >forever. If a candidate cannot use LTspice, he is of no use to me. > >You cannot tell if a circuit will work by looking at it. You have to find >a way to analyze it that is faster than pencil and paper. The old hybrid- >pi models are useless to see if a circuit is usable. Unfortunately, these >are stiil taught in engineering schools. > >My criteria for hiring a new employee would be to show how they are able >to construct simple circuits in LTspice and show how they work. If they >cannot do that, they are of very little use to me. > >Your claim that you can tell if a circuit works by simply looking at it >is feeble. You need to prove it works, and LTspice is the best way to >start. Hey, I am retired myself, so some time to play with stuff. There is such a thing as 'experience', I have seen thousands and thousands circuits, I have had to repair those too at times, I have a pretty good feel what fails and what does not. I did both design and repair of stuff, including very high end stuff from media to mil to science. To 'prove' something works there is only reality. I do not give a <...> if you (mathematically) prove say a wormhole to me (people do), but if I can buy it and travel through it and can come back to tell, I won't ask my money back. Hiring interviews is always interesting, there are often other forces than tech at work, say discrimination, personal preferences, friends of somebody... politics. Then, simple relay driver one transistor, forget the diode... I had a repair shop, let them repair a set. In show business there is 'the show must go on' you have to know the stuff in depth, enough to improvise and invent on the spot or fault find in 1 minute in equipment most here never even could fathom in 10 years of study. And, with electronics, things are always in motion, you study forever, [LT]spice is just a small niche in it all, toy basically. The human neural net configuration and weights is where it really is, that is why it is different for everybody. Until the day we can transfer that neural net configuration and weights, teh new kids on teh block will have to start again from scratch. But now they chase Pokemon and want Python... OK. And Dinos are no more either. You gotta give it to the last Dino, if he had a good time he was doing OK.
[toc] | [prev] | [next] | [standalone]
| From | Jan Panteltje <pNa0nStpealmtje@yahoo.com> |
|---|---|
| Date | 2017-05-15 19:13 +0000 |
| Message-ID | <ofculk$19cu$1@gioia.aioe.org> |
| In reply to | #460378 |
On a sunny day (Mon, 15 May 2017 13:30:20 -0400) it happened bitrex <bitrex@de.lete.earthlink.net> wrote in <MAlSA.118066$ef.9536@fx34.iad>: >On 05/15/2017 01:18 PM, Steve Wilson wrote: >> Jan Panteltje <pNa0nStpealmtje@yahoo.com> wrote: >> >>> On a sunny day (Mon, 15 May 2017 16:24:56 GMT) it happened Steve >>> Wilson <no@spam.com> wrote in >>> <XnsA7767E5052407idtokenpost@69.16.179.22>: >>> >>>> bitrex <bitrex@de.lete.earthlink.net> wrote: >>>> >>>>> On 05/15/2017 10:09 AM, bitrex wrote: >>>>>> On 05/15/2017 10:01 AM, John Larkin wrote: >>>>>> >>>>>>> BW is 230 MHz as a unity-gain buffer. Each half of the dual will >>>>>>> source and sink 88 mA. And there are lots of faster THS-series >>>>>>> parts. >>>>>>> >>>>>>>> >>>>>>>> But indeed you can do that with a few NPNs of the old days, >>>>>>>> >>>>>>> >>>>>>> Post it. >>>>>> >>>>>> With discretes you can have: >>>>>> >>>>>> 1) wide bandwidth >>>>>> >>>>>> 2) low parts count >>>>>> >>>>>> 3) low quiescent current draw >>>>>> >>>>>> Pick two. >>>>> >>>>> The two transistor circuit Jan posted does have a pretty wide >>>>> bandwidth and a low parts count. It has a pretty nice small signal >>>>> output impedance, but its large-signal output impedance is bad. It >>>>> also draws a relatively large amount of quiescent current. >>>> >>>> I somehow missed the two transistor circuit that Jan posted. Can you >>>> please repost the link? >>>> >>>> Thanks >>> >>> From: >>> http://panteltje.com/panteltje/quadcopter/hud.html >>> the circuit diagram: >>> http://panteltje.com/panteltje/quadcopter/hud-0.1_circuit_diagram_IMG >>> _5984.JPG bottom left: >>> that has a gain of 2, so can drive a 75 Ohm cable with reasonable Zi. >>> The DC path requires an other 75 Ohm at the end of the cable. >> >> OK, thanks. >> >> That is a Sziklai Pair with a voltage divider in the feedback path: >> >> https://en.wikipedia.org/wiki/Sziklai_pair >> >> It would normally have the same thermal drift as a simple base-emitter >> junction, but the divide by two may increase it. >> >> The output impedance may be increased due to the low loop gain. The >> bandwidth is determined by the transistors you use. > >Its output impedance for large negative-going signals is _dogshit_, >regardless of what the small-signal analysis feedback-loop-gain etc. >calculations indicate. It can source current okay. It definitely can't >sink it. > >It doesn't really matter for a composite video signal, though, because >it's not really that wide a bandwidth signal. The only potentially >difficult fast full-level transition I think of would be if you have to >go from the "back porch" immediately to "full luminance." Well that is same as from black to white, works fine tough. that is just the PNP conducting pulling the output. This circuit has been used for video by me many many times. Never ever failed.
[toc] | [prev] | [next] | [standalone]
| From | bitrex <bitrex@de.lete.earthlink.net> |
|---|---|
| Date | 2017-05-15 15:33 -0400 |
| Message-ID | <0onSA.73595$jO6.6010@fx41.iad> |
| In reply to | #460408 |
On 05/15/2017 03:13 PM, Jan Panteltje wrote: > Well that is same as from black to white, works fine tough. > that is just the PNP conducting pulling the output. > This circuit has been used for video by me many many times. > Never ever failed. Ya I'm sure it works fine for composite video. If the risetime off the porches is a little sluggish I don't think it matters much; there isn't anything timing-critical to that transition as its just setting up the luminance "data." Might make the edges a little fuzzy? Like "vintage warmth"
[toc] | [prev] | [next] | [standalone]
| From | Jan Panteltje <pNa0nStpealmtje@yahoo.com> |
|---|---|
| Date | 2017-05-16 08:16 +0000 |
| Message-ID | <ofecgl$1aje$1@gioia.aioe.org> |
| In reply to | #460412 |
On a sunny day (Mon, 15 May 2017 15:33:15 -0400) it happened bitrex <bitrex@de.lete.earthlink.net> wrote in <0onSA.73595$jO6.6010@fx41.iad>: >On 05/15/2017 03:13 PM, Jan Panteltje wrote: > >> Well that is same as from black to white, works fine tough. >> that is just the PNP conducting pulling the output. >> This circuit has been used for video by me many many times. >> Never ever failed. > >Ya I'm sure it works fine for composite video. If the risetime off the >porches is a little sluggish I don't think it matters much; there isn't >anything timing-critical to that transition as its just setting up the >luminance "data." Might make the edges a little fuzzy? Like "vintage warmth" It (the amplifier) is > 5MHz bandwidth, this is analog NTSC send down from the drone at 5.something GHz. You do NOT want faster risetimes etc in analog PAL / NTSC video. It only adds crap (plenty HF noise in that FM link) . You are no video man it seems, you talk about 'porches' nobody in video does.
[toc] | [prev] | [next] | [standalone]
| From | bitrex <bitrex@de.lete.earthlink.net> |
|---|---|
| Date | 2017-05-16 22:10 -0400 |
| Message-ID | <siOSA.91240$sS7.36334@fx40.iad> |
| In reply to | #460479 |
On 05/16/2017 04:16 AM, Jan Panteltje wrote: > On a sunny day (Mon, 15 May 2017 15:33:15 -0400) it happened bitrex > <bitrex@de.lete.earthlink.net> wrote in <0onSA.73595$jO6.6010@fx41.iad>: > >> On 05/15/2017 03:13 PM, Jan Panteltje wrote: >> >>> Well that is same as from black to white, works fine tough. >>> that is just the PNP conducting pulling the output. >>> This circuit has been used for video by me many many times. >>> Never ever failed. >> >> Ya I'm sure it works fine for composite video. If the risetime off the >> porches is a little sluggish I don't think it matters much; there isn't >> anything timing-critical to that transition as its just setting up the >> luminance "data." Might make the edges a little fuzzy? Like "vintage warmth" > > It (the amplifier) is > 5MHz bandwidth, > this is analog NTSC send down from the drone at 5.something GHz. > You do NOT want faster risetimes etc in analog PAL / NTSC video. > It only adds crap (plenty HF noise in that FM link) . > You are no video man it seems, you talk about 'porches' nobody in video does. > No, I've never really designed or worked with analog video amps/RF modulators/NTSC etc. I'm in my 30s, for most of my adult life "video" means "you plug in the magic (digital) cable and it works." I only know the terms and a little bit about that technology, like 8 track players and vacuum-tube computers, from what you might call "books of historical interest" ;-)
[toc] | [prev] | [next] | [standalone]
| From | Jan Panteltje <pNa0nStpealmtje@yahoo.com> |
|---|---|
| Date | 2017-05-15 19:10 +0000 |
| Message-ID | <ofcuff$1938$1@gioia.aioe.org> |
| In reply to | #460376 |
On a sunny day (Mon, 15 May 2017 17:18:17 GMT) it happened Steve Wilson <no@spam.com> wrote in <XnsA776875EB8A7idtokenpost@69.16.179.23>: >Jan Panteltje <pNa0nStpealmtje@yahoo.com> wrote: > >> On a sunny day (Mon, 15 May 2017 16:24:56 GMT) it happened Steve >> Wilson <no@spam.com> wrote in >> <XnsA7767E5052407idtokenpost@69.16.179.22>: >> >>>bitrex <bitrex@de.lete.earthlink.net> wrote: >>> >>>> On 05/15/2017 10:09 AM, bitrex wrote: >>>>> On 05/15/2017 10:01 AM, John Larkin wrote: >>>>> >>>>>> BW is 230 MHz as a unity-gain buffer. Each half of the dual will >>>>>> source and sink 88 mA. And there are lots of faster THS-series >>>>>> parts. >>>>>> >>>>>>> >>>>>>> But indeed you can do that with a few NPNs of the old days, >>>>>>> >>>>>> >>>>>> Post it. >>>>> >>>>> With discretes you can have: >>>>> >>>>> 1) wide bandwidth >>>>> >>>>> 2) low parts count >>>>> >>>>> 3) low quiescent current draw >>>>> >>>>> Pick two. >>>> >>>> The two transistor circuit Jan posted does have a pretty wide >>>> bandwidth and a low parts count. It has a pretty nice small signal >>>> output impedance, but its large-signal output impedance is bad. It >>>> also draws a relatively large amount of quiescent current. >>> >>>I somehow missed the two transistor circuit that Jan posted. Can you >>>please repost the link? >>> >>>Thanks >> >> From: >> http://panteltje.com/panteltje/quadcopter/hud.html >> the circuit diagram: >> http://panteltje.com/panteltje/quadcopter/hud-0.1_circuit_diagram_IMG >> _5984.JPG bottom left: >> that has a gain of 2, so can drive a 75 Ohm cable with reasonable Zi. >> The DC path requires an other 75 Ohm at the end of the cable. > >OK, thanks. > >That is a Sziklai Pair with a voltage divider in the feedback path: > > https://en.wikipedia.org/wiki/Sziklai_pair > >It would normally have the same thermal drift as a simple base-emitter >junction, but the divide by two may increase it. > >The output impedance may be increased due to the low loop gain. The >bandwidth is determined by the transistors you use. > >But it is difficult to tell what the transistors are due to the poor >clarity of the handwritten numbers. I can't read them even when I expand >the drawing. > >I really wish you could convert some of your critical circuits to LTspice >so we can see the operation a bit better. That would have a far greater >impact for the value of your work. Well OK, it is BC547-B / BC557-B (B is the beta range) Sometimes I wonder what sort of monitor or viewer people use... It may be that in some cases LTspice can not do my circuits :-)
[toc] | [prev] | [next] | [standalone]
| From | John Larkin <jjlarkin@highlandtechnology.com> |
|---|---|
| Date | 2017-05-15 08:55 -0700 |
| Message-ID | <olijhcpho27g4v0p033dtk3ucnhrip9r78@4ax.com> |
| In reply to | #460340 |
On Mon, 15 May 2017 10:09:39 -0400, bitrex <bitrex@de.lete.earthlink.net> wrote: >On 05/15/2017 10:01 AM, John Larkin wrote: > >> BW is 230 MHz as a unity-gain buffer. Each half of the dual will >> source and sink 88 mA. And there are lots of faster THS-series parts. >> >>> >>> But indeed you can do that with a few NPNs of the old days, >>> >> >> Post it. > >With discretes you can have: > >1) wide bandwidth > >2) low parts count > >3) low quiescent current draw > >Pick two. But your circuit has 24 parts and doesn't even have a voltage gain of 1. Snoop the input current of that buffer. At 20 MHz, the overall current gain is less than 1. At 100 MHz, the current gain is about 0.1. You'd be better off with a piece of wire. Designing discrete stuff if fun, but engineers need to be pragmatic, too. Buying an opamps gets things done. It's disappointing that, when you design a really good discrete circuit, the parts go EOL and some smart-alec makes an IC that does it better. -- John Larkin Highland Technology, Inc lunatic fringe electronics
[toc] | [prev] | [next] | [standalone]
| From | bitrex <bitrex@de.lete.earthlink.net> |
|---|---|
| Date | 2017-05-15 12:51 -0400 |
| Message-ID | <X%kSA.57721$BW5.49809@fx28.iad> |
| In reply to | #460355 |
On 05/15/2017 11:55 AM, John Larkin wrote: > On Mon, 15 May 2017 10:09:39 -0400, bitrex > <bitrex@de.lete.earthlink.net> wrote: > >> On 05/15/2017 10:01 AM, John Larkin wrote: >> >>> BW is 230 MHz as a unity-gain buffer. Each half of the dual will >>> source and sink 88 mA. And there are lots of faster THS-series parts. >>> >>>> >>>> But indeed you can do that with a few NPNs of the old days, >>>> >>> >>> Post it. >> >> With discretes you can have: >> >> 1) wide bandwidth >> >> 2) low parts count >> >> 3) low quiescent current draw >> >> Pick two. > > But your circuit has 24 parts and doesn't even have a voltage gain of > 1. > > Snoop the input current of that buffer. At 20 MHz, the overall current > gain is less than 1. At 100 MHz, the current gain is about 0.1. You'd > be better off with a piece of wire. I'm not sure what "input current" you're looking at. I'm seeing an average current of around 600uA into the MOSFET gates at 100MHz. Integrating the source you get that it's sourcing about 100uW, and a simple a 50 ohm load termination is dissipating 10mW. Assuming 100uW is the max the source could provide, what kind of length of wire has a a transducer gain of 100? That's a neat trick!
[toc] | [prev] | [next] | [standalone]
| From | bitrex <bitrex@de.lete.earthlink.net> |
|---|---|
| Date | 2017-05-15 12:56 -0400 |
| Message-ID | <Z4lSA.28966$9o7.20615@fx12.iad> |
| In reply to | #460369 |
On 05/15/2017 12:51 PM, bitrex wrote: > On 05/15/2017 11:55 AM, John Larkin wrote: >> On Mon, 15 May 2017 10:09:39 -0400, bitrex >> <bitrex@de.lete.earthlink.net> wrote: >> >>> On 05/15/2017 10:01 AM, John Larkin wrote: >>> >>>> BW is 230 MHz as a unity-gain buffer. Each half of the dual will >>>> source and sink 88 mA. And there are lots of faster THS-series parts. >>>> >>>>> >>>>> But indeed you can do that with a few NPNs of the old days, >>>>> >>>> >>>> Post it. >>> >>> With discretes you can have: >>> >>> 1) wide bandwidth >>> >>> 2) low parts count >>> >>> 3) low quiescent current draw >>> >>> Pick two. >> >> But your circuit has 24 parts and doesn't even have a voltage gain of >> 1. >> >> Snoop the input current of that buffer. At 20 MHz, the overall current >> gain is less than 1. At 100 MHz, the current gain is about 0.1. You'd >> be better off with a piece of wire. > > I'm not sure what "input current" you're looking at. I'm seeing an > average current of around 600uA into the MOSFET gates at 100MHz. > > Integrating the source you get that it's sourcing about 100uW, and a > simple a 50 ohm load termination is dissipating 10mW. > > Assuming 100uW is the max the source could provide, what kind of length > of wire has a a transducer gain of 100? That's a neat trick! If I had a square-wave source capable of providing say 200mA P2P with an infinite slew rate and zero output impedance then indeed, a piece of wire would be the perfect output buffer. Where do I get one of those?
[toc] | [prev] | [next] | [standalone]
| From | bitrex <bitrex@de.lete.earthlink.net> |
|---|---|
| Date | 2017-05-15 13:05 -0400 |
| Message-ID | <AdlSA.10749$7j4.7349@fx22.iad> |
| In reply to | #460371 |
On 05/15/2017 12:56 PM, bitrex wrote: > > I'm not sure what "input current" you're looking at. I'm seeing an > average current of around 600uA into the MOSFET gates at 100MHz. > > Integrating the source you get that it's sourcing about 100uW, and a > simple a 50 ohm load termination is dissipating 10mW. > > Assuming 100uW is the max the source could provide, what kind of length > of wire has a a transducer gain of 100? That's a neat trick! Sorry, I screwed that up. The average current out of the source is 100uA
[toc] | [prev] | [next] | [standalone]
| From | John Larkin <jjlarkin@highland_snip_technology.com> |
|---|---|
| Date | 2017-05-15 10:28 -0700 |
| Message-ID | <p7ojhch70bdi76ol1rf0j1ntika7c4aqen@4ax.com> |
| In reply to | #460369 |
On Mon, 15 May 2017 12:51:03 -0400, bitrex <bitrex@de.lete.earthlink.net> wrote: >On 05/15/2017 11:55 AM, John Larkin wrote: >> On Mon, 15 May 2017 10:09:39 -0400, bitrex >> <bitrex@de.lete.earthlink.net> wrote: >> >>> On 05/15/2017 10:01 AM, John Larkin wrote: >>> >>>> BW is 230 MHz as a unity-gain buffer. Each half of the dual will >>>> source and sink 88 mA. And there are lots of faster THS-series parts. >>>> >>>>> >>>>> But indeed you can do that with a few NPNs of the old days, >>>>> >>>> >>>> Post it. >>> >>> With discretes you can have: >>> >>> 1) wide bandwidth >>> >>> 2) low parts count >>> >>> 3) low quiescent current draw >>> >>> Pick two. >> >> But your circuit has 24 parts and doesn't even have a voltage gain of >> 1. >> >> Snoop the input current of that buffer. At 20 MHz, the overall current >> gain is less than 1. At 100 MHz, the current gain is about 0.1. You'd >> be better off with a piece of wire. > >I'm not sure what "input current" you're looking at. I'm seeing an >average current of around 600uA into the MOSFET gates at 100MHz. I put a 1 mohm resistor in series with the signal generator and probed the current, with a sine wave signal input. Try it and see what you get. Assume 1 volt peak input at 100 MHz. And 600 uA peak (not average!) current. That works out to a capacitance of 1 pF. That sounds improbable. Ciss of that fet is 3600 pF. > >Integrating the source you get that it's sourcing about 100uW, and a >simple a 50 ohm load termination is dissipating 10mW. Apply a 1 volt 100 MHz sine input and measure the V+ supply current. > >Assuming 100uW is the max the source could provide, what kind of length >of wire has a a transducer gain of 100? That's a neat trick! -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
[toc] | [prev] | [next] | [standalone]
| From | bitrex <bitrex@de.lete.earthlink.net> |
|---|---|
| Date | 2017-05-15 13:38 -0400 |
| Message-ID | <7IlSA.115866$jP5.11583@fx03.iad> |
| In reply to | #460377 |
On 05/15/2017 01:28 PM, John Larkin wrote: >>> Snoop the input current of that buffer. At 20 MHz, the overall current >>> gain is less than 1. At 100 MHz, the current gain is about 0.1. You'd >>> be better off with a piece of wire. >> >> I'm not sure what "input current" you're looking at. I'm seeing an >> average current of around 600uA into the MOSFET gates at 100MHz. > > I put a 1 mohm resistor in series with the signal generator and probed > the current, with a sine wave signal input. Try it and see what you > get. How are the gate capacitances of the input MOSFETs supposed to be charged up and down with that fuckin' thing sitting in the way?! Fuck the circuit to hell and then complain it's bad?! Shit! :O
[toc] | [prev] | [next] | [standalone]
| From | John Larkin <jjlarkin@highland_snip_technology.com> |
|---|---|
| Date | 2017-05-15 11:29 -0700 |
| Message-ID | <ncsjhc9r176kl3q1cd2b9kcsaujqlf64pk@4ax.com> |
| In reply to | #460380 |
On Mon, 15 May 2017 13:38:11 -0400, bitrex <bitrex@de.lete.earthlink.net> wrote: >On 05/15/2017 01:28 PM, John Larkin wrote: > >>>> Snoop the input current of that buffer. At 20 MHz, the overall current >>>> gain is less than 1. At 100 MHz, the current gain is about 0.1. You'd >>>> be better off with a piece of wire. >>> >>> I'm not sure what "input current" you're looking at. I'm seeing an >>> average current of around 600uA into the MOSFET gates at 100MHz. >> >> I put a 1 mohm resistor in series with the signal generator and probed >> the current, with a sine wave signal input. Try it and see what you >> get. > >How are the gate capacitances of the input MOSFETs supposed to be >charged up and down with that fuckin' thing sitting in the way?! > >Fuck the circuit to hell and then complain it's bad?! Shit! :O mohm means milliohm, in SI units and in Spice. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
[toc] | [prev] | [next] | [standalone]
Page 3 of 7 — ← Prev page 1 2 [3] 4 5 6 7 Next page →
Back to top | Article view | sci.electronics.design
csiph-web