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Groups > sci.electronics.equipment > #367 > unrolled thread
| Started by | "Commander Kinsey" <CFKinsey@military.org.jp> |
|---|---|
| First post | 2020-06-18 14:03 +0100 |
| Last post | 2020-06-24 20:03 +0000 |
| Articles | 20 on this page of 103 — 11 participants |
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Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-06-18 14:03 +0100
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-06-18 14:28 +0100
Re: Error of % + digits? Pimpom <nobody@nowhere.com> - 2020-06-18 20:08 +0530
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-06-18 15:41 +0100
Re: Error of % + digits? Ralph Mowery <rmowery28146@earthlink.net> - 2020-06-18 18:16 -0400
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-06-18 23:48 +0100
Re: Error of % + digits? Ralph Mowery <rmowery28146@earthlink.net> - 2020-06-18 19:38 -0400
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-06-19 21:46 +0100
Re: Error of % + digits? Ralph Mowery <rmowery28146@earthlink.net> - 2020-06-19 18:55 -0400
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-06-19 23:59 +0100
Re: Error of % + digits? Pimpom <nobody@nowhere.com> - 2020-06-20 12:09 +0530
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-06-20 13:03 +0100
Re: Error of % + digits? Ralph Mowery <rmowery28146@earthlink.net> - 2020-06-20 11:24 -0400
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-06-20 16:58 +0100
Re: Error of % + digits? Pimpom <nobody@nowhere.com> - 2020-06-20 23:28 +0530
Re: Error of % + digits? Ralph Mowery <rmowery28146@earthlink.net> - 2020-06-20 14:15 -0400
Re: Error of % + digits? Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-06-20 23:54 +0100
Re: Error of % + digits? Cydrome Leader <presence@MUNGEpanix.com> - 2020-06-26 05:10 +0000
Re: Error of % + digits? Ralph Mowery <rmowery28146@earthlink.net> - 2020-06-26 11:27 -0400
Re: Error of % + digits? Cydrome Leader <presence@MUNGEpanix.com> - 2020-06-27 06:40 +0000
Re: Error of % + digits? Ralph Mowery <rmowery28146@earthlink.net> - 2020-06-27 09:55 -0400
Re: Error of % + digits? Cydrome Leader <presence@MUNGEpanix.com> - 2020-06-29 02:59 +0000
Re: Error of % + digits? Ralph Mowery <rmowery28146@earthlink.net> - 2020-06-29 10:54 -0400
Re: Error of % + digits? Cydrome Leader <presence@MUNGEpanix.com> - 2020-06-30 03:28 +0000
Re: Error of % + digits? Jeroen Belleman <jeroen@nospam.please> - 2020-06-20 20:18 +0200
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-06-24 18:37 +0100
Re: Error of % + digits? Cydrome Leader <presence@MUNGEpanix.com> - 2020-06-26 04:54 +0000
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-11 21:38 +0100
Re: Error of % + digits? Cydrome Leader <presence@MUNGEpanix.com> - 2020-07-13 03:21 +0000
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-13 13:32 +0100
Re: Error of % + digits? Cydrome Leader <presence@MUNGEpanix.com> - 2020-06-26 04:23 +0000
Re: Error of % + digits? Pimpom <nobody@nowhere.com> - 2020-06-26 14:02 +0530
Re: Error of % + digits? Cydrome Leader <presence@MUNGEpanix.com> - 2020-06-27 06:56 +0000
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-12 18:45 +0100
Re: Error of % + digits? Pimpom <nobody@nowhere.com> - 2020-07-12 23:31 +0530
Re: Error of % + digits? Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-07-12 20:21 +0100
Re: Error of % + digits? Pimpom <nobody@nowhere.com> - 2020-07-13 10:23 +0530
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-13 13:36 +0100
Re: Error of % + digits? Pimpom <nobody@nowhere.com> - 2020-07-13 20:57 +0530
Re: Error of % + digits? Jeroen Belleman <jeroen@nospam.please> - 2020-07-13 17:39 +0200
Re: Error of % + digits? Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-07-13 21:04 +0100
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-20 21:35 +0100
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-20 21:36 +0100
Re: Error of % + digits? Pimpom <nobody@nowhere.com> - 2020-07-21 12:05 +0530
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-31 23:53 +0100
Re: Error of % + digits? Pimpom <nobody@nowhere.com> - 2020-08-01 14:31 +0530
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-13 13:35 +0100
Re: Error of % + digits? Cydrome Leader <presence@MUNGEpanix.com> - 2020-07-16 07:30 +0000
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-17 00:19 +0100
Re: Error of % + digits? Cydrome Leader <presence@MUNGEpanix.com> - 2020-07-21 01:13 +0000
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-08-04 22:27 +0100
Re: Error of % + digits? Cydrome Leader <presence@MUNGEpanix.com> - 2020-09-09 07:39 +0000
Re: Error of % + digits? Jasen Betts <jasen@xnet.co.nz> - 2020-07-17 12:15 +0000
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-28 19:02 +0100
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-13 13:38 +0100
Re: Error of % + digits? Rich <rich@example.invalid> - 2020-06-24 20:06 +0000
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-06-30 00:41 +0100
Re: Error of % + digits? Cydrome Leader <presence@MUNGEpanix.com> - 2020-06-30 03:52 +0000
Re: Error of % + digits? Ralph Mowery <rmowery28146@earthlink.net> - 2020-06-30 11:09 -0400
Re: Error of % + digits? Cydrome Leader <presence@MUNGEpanix.com> - 2020-07-02 05:45 +0000
Re: Error of % + digits? Jasen Betts <jasen@xnet.co.nz> - 2020-07-02 07:03 +0000
Re: Error of % + digits? Ralph Mowery <rmowery28146@earthlink.net> - 2020-07-02 10:41 -0400
Re: Error of % + digits? RheillyPhoull <Rheilly@bigslong.com> - 2020-07-03 09:20 +0800
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-16 20:09 +0100
Re: Separate amps jacks on multimeters Rich <rich@example.invalid> - 2020-07-17 14:02 +0000
Re: Separate amps jacks on multimeters "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-17 19:16 +0100
Re: Separate amps jacks on multimeters Rich <rich@example.invalid> - 2020-07-17 20:26 +0000
Re: Separate amps jacks on multimeters "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-17 21:44 +0100
Re: Separate amps jacks on multimeters Rich <rich@example.invalid> - 2020-07-17 22:37 +0000
Re: Separate amps jacks on multimeters "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-18 00:11 +0100
Re: Separate amps jacks on multimeters Ralph Mowery <rmowery28146@earthlink.net> - 2020-07-17 18:07 -0400
Re: Separate amps jacks on multimeters "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-17 23:31 +0100
Re: Separate amps jacks on multimeters Ralph Mowery <rmowery28146@earthlink.net> - 2020-07-17 19:10 -0400
Re: Separate amps jacks on multimeters "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-18 00:18 +0100
Re: Separate amps jacks on multimeters Ralph Mowery <rmowery28146@earthlink.net> - 2020-07-17 19:30 -0400
Re: Separate amps jacks on multimeters "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-28 22:16 +0100
Re: Separate amps jacks on multimeters Cydrome Leader <presence@MUNGEpanix.com> - 2020-07-22 04:24 +0000
Re: Separate amps jacks on multimeters Ralph Mowery <rmowery28146@earthlink.net> - 2020-07-22 12:28 -0400
Re: Separate amps jacks on multimeters Ralph Mowery <rmowery28146@earthlink.net> - 2020-07-17 19:25 -0400
Re: Separate amps jacks on multimeters Cydrome Leader <presence@MUNGEpanix.com> - 2020-07-22 04:20 +0000
Re: Separate amps jacks on multimeters Ralph Mowery <rmowery28146@earthlink.net> - 2020-07-22 12:23 -0400
Re: Error of % + digits? Jasen Betts <jasen@xnet.co.nz> - 2020-07-03 13:10 +0000
Re: Error of % + digits? Ralph Mowery <rmowery28146@earthlink.net> - 2020-07-03 10:14 -0400
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-16 20:10 +0100
Re: Error of % + digits? Ralph Mowery <rmowery28146@earthlink.net> - 2020-07-16 16:03 -0400
Re: Error of % + digits? Michael Terrell <terrell.michael.a@gmail.com> - 2020-07-16 13:13 -0700
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-17 00:02 +0100
Re: Error of % + digits? Ralph Mowery <rmowery28146@earthlink.net> - 2020-07-16 23:29 -0400
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-24 22:09 +0100
Re: Error of % + digits? Rich <rich@example.invalid> - 2020-07-24 22:58 +0000
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-25 00:31 +0100
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-17 00:01 +0100
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-16 18:51 +0100
Re: Error of % + digits? Cydrome Leader <presence@MUNGEpanix.com> - 2020-07-26 03:53 +0000
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-16 18:45 +0100
Re: Error of % + digits? Ralph Mowery <rmowery28146@earthlink.net> - 2020-07-16 15:53 -0400
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-16 18:46 +0100
Re: Error of % + digits? Michael Terrell <terrell.michael.a@gmail.com> - 2020-07-16 10:54 -0700
Re: Error of % + digits? "Commander Kinsey" <CFKinsey@military.org.jp> - 2020-07-17 00:15 +0100
Re: Error of % + digits? Cydrome Leader <presence@MUNGEpanix.com> - 2020-07-26 04:17 +0000
Re: Error of % + digits? Rich <rich@example.invalid> - 2020-06-30 07:59 +0000
Re: Error of % + digits? Dieter Michel <dmichel@prosound.de> - 2020-06-22 17:19 +0200
Re: Error of % + digits? Rich <rich@example.invalid> - 2020-06-24 20:03 +0000
Page 4 of 6 — ← Prev page 1 2 3 [4] 5 6 Next page →
| From | Jasen Betts <jasen@xnet.co.nz> |
|---|---|
| Date | 2020-07-02 07:03 +0000 |
| Message-ID | <rdk0ru$sai$1@gonzo.revmaps.no-ip.org> |
| In reply to | #405 |
On 2020-07-02, Cydrome Leader <presence@MUNGEpanix.com> wrote: > In sci.electronics.equipment Ralph Mowery <rmowery28146@earthlink.net> wrote: >> In article <rdecuc$m73$1@reader1.panix.com>, presence@MUNGEpanix.com >> says... >>> >>> > So should I assume the cheaper ones are lying? Or have they just made a rough estimate adding the two errors? >>> >>> might be both. I dug out my first DMM, a Wavetek DM2, circa 1990s. It might >>> have been from a raffle or something like that. >>> >>> The DC voltage specs range from 0.8% +1 digit (not bad really) over to the >>> AC ranges which are "1.2% RDG +10 Digits". If I had new leads, I'd trust it >>> with outlet voltage, but would stay away from 208volts. The meter has 3.5 >>> digits or max display of 1999. I'm figuring a real 100volt AC reading could >>> be 99 to 101 plus another error of +/- 1 volt for the 10 digits tolerance >>> on the display or count. so 100volts from your Japanese outlet reference >>> might read 98 to 102 volts. So while in the ballpark, it's better than you >>> can read off a Simpson 260 meter in the AC voltage range. I could be wrong >>> on this too. >>> >>> It's a pretty decent meter for poking at DC circuits for the tens of >>> dollars is must have cost when new. >>> >>> >> >> It seems that maybe due to modern manufactoring the meters are more >> accurate than they were 20 years ago. I bought some DC voltmeters from >> China. They display 3 digits. They read from 0 to 99.9 volts. I coulg >> get 4 of them for less than $ 15 including the shipping. I hooked all 4 >> of them in parallel with a Fluke 87 . Three of them tracked right along >> with the Fluke with the last digit sometimes being one high or low from >> 0 to 24 volts. The fourth one was off by an average of 2 on the last >> digit. I found an adjustment screw on the back of the meter and tweaked >> it and re ran the test. It then fell in line with the other meters. > > Have you run this test with AC? That seems to be where the wheels come > off. I brought up this thread to a friend and he mentioned his quest to > repair some sort of HP true RMS meter that uses a thermocouple and heater > to properly measure complex waveforms. I can't even guess how slow such a > meter might be. The heaters used in thermal printers manage a speed better than 10mS stuff done in a microchip (like LT1088) could be even faster. -- Jasen.
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| From | Ralph Mowery <rmowery28146@earthlink.net> |
|---|---|
| Date | 2020-07-02 10:41 -0400 |
| Message-ID | <MPG.3967bbf9e219d905989f40@news.east.earthlink.net> |
| In reply to | #405 |
In article <rdjsa6$28b$1@reader1.panix.com>, presence@MUNGEpanix.com says... > > Have you run this test with AC? That seems to be where the wheels come > off. I brought up this thread to a friend and he mentioned his quest to > repair some sort of HP true RMS meter that uses a thermocouple and heater > to properly measure complex waveforms. I can't even guess how slow such a > meter might be. > > > I had 3 or 4 of the Harbor Freight 'free' multimeters. The ones that > > usually sell for around $ 5. They seem to be reasonable accurate for > > the money. Plenty accurate for the home user to test things around the > > house. I do admit that the safety issue of putting them across the 120 > > or 240 volt power wires is somewhat doubtful. I sure would not use one > > where I worked to put across the 480 volt 3 phase system that is fused > > with 200 amps. > > I'm pretty timid with anything upstream from a plain outlet. I had an > edison base fuse burst in my hand once. Never seen one come apart before. > It was just a 120v lighting circuit, but right off the service panel. > There's way more excitement near those things. > > I have not ran any tests for AC . The things I work with don't care about very much about being accurate to more than around 5 %. Usually it is more of do I have a voltage/current or not. When I work on most anything other than low voltage (below 100 volts) I ues either my Simpson 260 analog meter or a Fluke meter that is rated for cat 3 and 4. If you have not heard of the Cat numbers, they are for devices used in different power circuits. I don't know the numbers off hand, but it goes something like this, Cat 1 is for low voltage items, Cat 2 for things like stoves and refrigerators, Cat 3 for homw wiring,and Cat 4 for the very high power circuits like I often worked on like the 480 volt AC and 300 amps. For a real scare you should see some of the safety movies that Fluke put out. They show under test conditions what can hapen to inexpensive meters and their meters under different conditions like having the meter set for amps and putting across a 480 volt circuit that has plenty of amps .
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| From | RheillyPhoull <Rheilly@bigslong.com> |
|---|---|
| Date | 2020-07-03 09:20 +0800 |
| Message-ID | <M8-dnVKqZKBoGmPDnZ2dnUU7-a2dnZ2d@westnet.com.au> |
| In reply to | #407 |
On 2/07/2020 10:41 pm, Ralph Mowery wrote: > In article <rdjsa6$28b$1@reader1.panix.com>, presence@MUNGEpanix.com > says... >> >> Have you run this test with AC? That seems to be where the wheels come >> off. I brought up this thread to a friend and he mentioned his quest to >> repair some sort of HP true RMS meter that uses a thermocouple and heater >> to properly measure complex waveforms. I can't even guess how slow such a >> meter might be. >> >>> I had 3 or 4 of the Harbor Freight 'free' multimeters. The ones that >>> usually sell for around $ 5. They seem to be reasonable accurate for >>> the money. Plenty accurate for the home user to test things around the >>> house. I do admit that the safety issue of putting them across the 120 >>> or 240 volt power wires is somewhat doubtful. I sure would not use one >>> where I worked to put across the 480 volt 3 phase system that is fused >>> with 200 amps. >> >> I'm pretty timid with anything upstream from a plain outlet. I had an >> edison base fuse burst in my hand once. Never seen one come apart before. >> It was just a 120v lighting circuit, but right off the service panel. >> There's way more excitement near those things. >> >> > > I have not ran any tests for AC . The things I work with don't care > about very much about being accurate to more than around 5 %. Usually > it is more of do I have a voltage/current or not. > > When I work on most anything other than low voltage (below 100 volts) I > ues either my Simpson 260 analog meter or a Fluke meter that is rated > for cat 3 and 4. If you have not heard of the Cat numbers, they are for > devices used in different power circuits. I don't know the numbers off > hand, but it goes something like this, Cat 1 is for low voltage items, > Cat 2 for things like stoves and refrigerators, Cat 3 for homw > wiring,and Cat 4 for the very high power circuits like I often worked on > like the 480 volt AC and 300 amps. > > For a real scare you should see some of the safety movies that Fluke put > out. They show under test conditions what can hapen to inexpensive > meters and their meters under different conditions like having the > meter set for amps and putting across a 480 volt circuit that has plenty > of amps . > Ahh the old "Leaving it on amps" trick. How many of us can say they never did it ?
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| From | "Commander Kinsey" <CFKinsey@military.org.jp> |
|---|---|
| Date | 2020-07-16 20:09 +0100 |
| Message-ID | <op.0nu3hup8wdg98l@glass> |
| In reply to | #408 |
On Fri, 03 Jul 2020 02:20:53 +0100, RheillyPhoull <Rheilly@bigslong.com> wrote: > On 2/07/2020 10:41 pm, Ralph Mowery wrote: >> In article <rdjsa6$28b$1@reader1.panix.com>, presence@MUNGEpanix.com >> says... >>> >>> Have you run this test with AC? That seems to be where the wheels come >>> off. I brought up this thread to a friend and he mentioned his quest to >>> repair some sort of HP true RMS meter that uses a thermocouple and heater >>> to properly measure complex waveforms. I can't even guess how slow such a >>> meter might be. >>> >>>> I had 3 or 4 of the Harbor Freight 'free' multimeters. The ones that >>>> usually sell for around $ 5. They seem to be reasonable accurate for >>>> the money. Plenty accurate for the home user to test things around the >>>> house. I do admit that the safety issue of putting them across the 120 >>>> or 240 volt power wires is somewhat doubtful. I sure would not use one >>>> where I worked to put across the 480 volt 3 phase system that is fused >>>> with 200 amps. >>> >>> I'm pretty timid with anything upstream from a plain outlet. I had an >>> edison base fuse burst in my hand once. Never seen one come apart before. >>> It was just a 120v lighting circuit, but right off the service panel. >>> There's way more excitement near those things. >>> >>> >> >> I have not ran any tests for AC . The things I work with don't care >> about very much about being accurate to more than around 5 %. Usually >> it is more of do I have a voltage/current or not. >> >> When I work on most anything other than low voltage (below 100 volts) I >> ues either my Simpson 260 analog meter or a Fluke meter that is rated >> for cat 3 and 4. If you have not heard of the Cat numbers, they are for >> devices used in different power circuits. I don't know the numbers off >> hand, but it goes something like this, Cat 1 is for low voltage items, >> Cat 2 for things like stoves and refrigerators, Cat 3 for homw >> wiring,and Cat 4 for the very high power circuits like I often worked on >> like the 480 volt AC and 300 amps. >> >> For a real scare you should see some of the safety movies that Fluke put >> out. They show under test conditions what can hapen to inexpensive >> meters and their meters under different conditions like having the >> meter set for amps and putting across a 480 volt circuit that has plenty >> of amps . >> > Ahh the old "Leaving it on amps" trick. How many of us can say they > never did it ? I find it crazy that you can select volts and have the wires in the amps holes. The switch should change the contacts. I've broken a meter doing that, just measuring the voltage on a car battery. £100 meter, but UNFUSED FFS! At least the mA range was fused, but they couldn't be bothered putting in a 20A fuse for the big range....
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| From | Rich <rich@example.invalid> |
|---|---|
| Date | 2020-07-17 14:02 +0000 |
| Subject | Re: Separate amps jacks on multimeters |
| Message-ID | <resb18$ejt$1@dont-email.me> |
| In reply to | #450 |
In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote: > On Fri, 03 Jul 2020 02:20:53 +0100, RheillyPhoull <Rheilly@bigslong.com> wrote: > >> On 2/07/2020 10:41 pm, Ralph Mowery wrote: >>> For a real scare you should see some of the safety movies that >>> Fluke put out. They show under test conditions what can hapen to >>> inexpensive meters and their meters under different conditions like >>> having the meter set for amps and putting across a 480 volt circuit >>> that has plenty of amps . >>> >> Ahh the old "Leaving it on amps" trick. How many of us can say they >> never did it ? > > I find it crazy that you can select volts and have the wires in the > amps holes. The switch should change the contacts. I've broken a > meter doing that, just measuring the voltage on a car battery. £100 > meter, but UNFUSED FFS! At least the mA range was fused, but they > couldn't be bothered putting in a 20A fuse for the big range.... The separate amps jacks exist for at least two reasons: 1) If the range switch also switched in/out the current shunt, then the user could accidentally create a short circult across the probe tips simply by turning the range switch to or across the amps measurement ranges. Even if they were quickly turning /across/ the amps settings ranges, a brief short circuit would be created, which would cause damage to the meter as well as the device under test depending upon what was connected at the time. 2) By having the amps jacks separate, the range switch itself does not have to have contacts beefy enough to carry the current for the amps settings. Remember, when measuring amps, the current being measured flows *through* the meter itself. This would require very different (and likely much more expensive) range switch contacts. Some meters do have sensors for the amps jacks that sound an alarm if the probes are inserted in the amps jacks but the range switch is on a different setting than amperes.
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| From | "Commander Kinsey" <CFKinsey@military.org.jp> |
|---|---|
| Date | 2020-07-17 19:16 +0100 |
| Subject | Re: Separate amps jacks on multimeters |
| Message-ID | <op.0nwvpyqqwdg98l@glass> |
| In reply to | #461 |
On Fri, 17 Jul 2020 15:02:16 +0100, Rich <rich@example.invalid> wrote: > In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote: >> On Fri, 03 Jul 2020 02:20:53 +0100, RheillyPhoull <Rheilly@bigslong.com> wrote: >> >>> On 2/07/2020 10:41 pm, Ralph Mowery wrote: >>>> For a real scare you should see some of the safety movies that >>>> Fluke put out. They show under test conditions what can hapen to >>>> inexpensive meters and their meters under different conditions like >>>> having the meter set for amps and putting across a 480 volt circuit >>>> that has plenty of amps . >>>> >>> Ahh the old "Leaving it on amps" trick. How many of us can say they >>> never did it ? >> >> I find it crazy that you can select volts and have the wires in the >> amps holes. The switch should change the contacts. I've broken a >> meter doing that, just measuring the voltage on a car battery. £100 >> meter, but UNFUSED FFS! At least the mA range was fused, but they >> couldn't be bothered putting in a 20A fuse for the big range.... > > The separate amps jacks exist for at least two reasons: > > 1) If the range switch also switched in/out the current shunt, then the > user could accidentally create a short circult across the probe tips > simply by turning the range switch to or across the amps measurement > ranges. Even if they were quickly turning /across/ the amps settings > ranges, a brief short circuit would be created, which would cause > damage to the meter as well as the device under test depending upon > what was connected at the time. Then you put the amps ranges on one end of the dial. You would never go through them. And what idiot turns the dial while it's connected?! > 2) By having the amps jacks separate, the range switch itself does not > have to have contacts beefy enough to carry the current for the amps > settings. Remember, when measuring amps, the current being measured > flows *through* the meter itself. This would require very different > (and likely much more expensive) range switch contacts. Or a relay. > Some meters do have sensors for the amps jacks that sound an alarm if > the probes are inserted in the amps jacks but the range switch is on a > different setting than amperes.
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| From | Rich <rich@example.invalid> |
|---|---|
| Date | 2020-07-17 20:26 +0000 |
| Subject | Re: Separate amps jacks on multimeters |
| Message-ID | <ret1h6$stk$1@dont-email.me> |
| In reply to | #462 |
In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote: > On Fri, 17 Jul 2020 15:02:16 +0100, Rich <rich@example.invalid> wrote: > >> In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote: >>> On Fri, 03 Jul 2020 02:20:53 +0100, RheillyPhoull <Rheilly@bigslong.com> wrote: >>> >>>> On 2/07/2020 10:41 pm, Ralph Mowery wrote: >>>>> For a real scare you should see some of the safety movies that >>>>> Fluke put out. They show under test conditions what can hapen to >>>>> inexpensive meters and their meters under different conditions like >>>>> having the meter set for amps and putting across a 480 volt circuit >>>>> that has plenty of amps . >>>>> >>>> Ahh the old "Leaving it on amps" trick. How many of us can say they >>>> never did it ? >>> >>> I find it crazy that you can select volts and have the wires in the >>> amps holes. The switch should change the contacts. I've broken a >>> meter doing that, just measuring the voltage on a car battery. £100 >>> meter, but UNFUSED FFS! At least the mA range was fused, but they >>> couldn't be bothered putting in a 20A fuse for the big range.... >> >> The separate amps jacks exist for at least two reasons: >> >> 1) If the range switch also switched in/out the current shunt, then the >> user could accidentally create a short circult across the probe tips >> simply by turning the range switch to or across the amps measurement >> ranges. Even if they were quickly turning /across/ the amps settings >> ranges, a brief short circuit would be created, which would cause >> damage to the meter as well as the device under test depending upon >> what was connected at the time. > > Then you put the amps ranges on one end of the dial. You would never > go through them. Some meters have range switches that rotate through a full 360 degrees with no stops - there would be no "end of the dial" in those instances. And even with an 'end of the dial' there is still the possibility of landing 'off by one' while turning the dial. > And what idiot turns the dial while it's connected?! The same idiot who'd leave the leads plugged into the amps jacks and then attempt to measure the voltage of a car battery (or some other low impedance high current voltage source). I suspect you would find changing the range switch while connected is much more common than your response implies. Esp. for switching up/down a range for meters that are not auto-ranging. >> 2) By having the amps jacks separate, the range switch itself does not >> have to have contacts beefy enough to carry the current for the amps >> settings. Remember, when measuring amps, the current being measured >> flows *through* the meter itself. This would require very different >> (and likely much more expensive) range switch contacts. > > Or a relay. Which also equates directly to added expense vs. having the user themselves be that "relay". And for battery powered meters, shorter battery life (due to the current consumed by the relay coil). It is also possible (this is a guess in my part) that the CAT ratings specify separate amps jacks for an added safety factor of "user must deliberately move lead to obtain short circuit through meter". As well, the user who'd leave the leads plugged into amps, and then try to measure voltage on car battery or other high current source is also just as likely to leave the range switch in the amps setting (after having measured current somewhere) and subsequently try to measure voltage. It is not possible to fully protect users who don't pay attention from doing stupid things. Either they forget to unplug from the amps jack, or they forget to switch away from the amps range, either way they get a local fireworks display of their own doing.
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| From | "Commander Kinsey" <CFKinsey@military.org.jp> |
|---|---|
| Date | 2020-07-17 21:44 +0100 |
| Subject | Re: Separate amps jacks on multimeters |
| Message-ID | <op.0nw2k3xcwdg98l@glass> |
| In reply to | #463 |
On Fri, 17 Jul 2020 21:26:15 +0100, Rich <rich@example.invalid> wrote: > In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote: >> On Fri, 17 Jul 2020 15:02:16 +0100, Rich <rich@example.invalid> wrote: >> >>> In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote: >>>> On Fri, 03 Jul 2020 02:20:53 +0100, RheillyPhoull <Rheilly@bigslong.com> wrote: >>>> >>>>> On 2/07/2020 10:41 pm, Ralph Mowery wrote: >>>>>> For a real scare you should see some of the safety movies that >>>>>> Fluke put out. They show under test conditions what can hapen to >>>>>> inexpensive meters and their meters under different conditions like >>>>>> having the meter set for amps and putting across a 480 volt circuit >>>>>> that has plenty of amps . >>>>>> >>>>> Ahh the old "Leaving it on amps" trick. How many of us can say they >>>>> never did it ? >>>> >>>> I find it crazy that you can select volts and have the wires in the >>>> amps holes. The switch should change the contacts. I've broken a >>>> meter doing that, just measuring the voltage on a car battery. £100 >>>> meter, but UNFUSED FFS! At least the mA range was fused, but they >>>> couldn't be bothered putting in a 20A fuse for the big range.... >>> >>> The separate amps jacks exist for at least two reasons: >>> >>> 1) If the range switch also switched in/out the current shunt, then the >>> user could accidentally create a short circult across the probe tips >>> simply by turning the range switch to or across the amps measurement >>> ranges. Even if they were quickly turning /across/ the amps settings >>> ranges, a brief short circuit would be created, which would cause >>> damage to the meter as well as the device under test depending upon >>> what was connected at the time. >> >> Then you put the amps ranges on one end of the dial. You would never >> go through them. > > Some meters have range switches that rotate through a full 360 degrees > with no stops - there would be no "end of the dial" in those instances. Then don't make them like that. > And even with an 'end of the dial' there is still the possibility of > landing 'off by one' while turning the dial. Then have a gap which is connected to nothing. >> And what idiot turns the dial while it's connected?! > > The same idiot who'd leave the leads plugged into the amps jacks and > then attempt to measure the voltage of a car battery Wrong. You adjust the dial to what you want to do, not remembering what you were measuring yesterday. Having only one thing to change makes it way easier to get it right. > (or some other low impedance high current voltage source). It only has to get over 20 amps to fuck the meter. > I suspect you would find changing the range switch while connected is > much more common than your response implies. Esp. for switching > up/down a range for meters that are not auto-ranging. Meters should always auto range. Mine all do, and I've never even considered adjusting the dial while it's connected. I'm not going to change between resistance, current, and volts and want to leave it connected to the same thing. >>> 2) By having the amps jacks separate, the range switch itself does not >>> have to have contacts beefy enough to carry the current for the amps >>> settings. Remember, when measuring amps, the current being measured >>> flows *through* the meter itself. This would require very different >>> (and likely much more expensive) range switch contacts. >> >> Or a relay. > > Which also equates directly to added expense vs. having the user > themselves be that "relay". No, because you save on an extra socket. > And for battery powered meters, shorter > battery life (due to the current consumed by the relay coil). Latching relays use very little indeed, like the one in my room thermostat. 2 AA batteries last years. > It is also possible (this is a guess in my part) that the CAT ratings > specify separate amps jacks for an added safety factor of "user must > deliberately move lead to obtain short circuit through meter". Then they're fools, because now "user can obtain short circuit by forgetting he was measuring current yesterday, or because a colleague was without him knowing". If it was selected on the dial, there is no possibility to make a mistake. You select what you want and that's what you get. It's illogical to have one thing pointing at volts while another thing is expecting current! Anyway, a simple fuse would solve all this. All you lose if you make a mistake is a fuse, not the internal workings of the meter, the test leads, the thing you're testing, and possibly your face. > As well, the user who'd leave the leads plugged into amps, and then try > to measure voltage on car battery or other high current source is also > just as likely to leave the range switch in the amps setting (after > having measured current somewhere) and subsequently try to measure > voltage. Nope. I pick up a multimeter and set it to what I'm about to measure. Same way as I don't drive into my house because I left my car in forward gear yesterday. > It is not possible to fully protect users who don't pay > attention from doing stupid things. Either they forget to unplug from > the amps jack, or they forget to switch away from the amps range, > either way they get a local fireworks display of their own doing. People make mistakes. The best equipment prevents this. My VW Golf for example would not allow me to select 1st gear when going 100mph. It was quite clever in fact. I could do that on purpose and it would drop one gear at a time to slow the car as quickly as possible to assist the brakes in an emergency. And yes I did try it a few times, one time I scared the shit out of the passenger (who had never seen an automatic gearbox before).
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| From | Rich <rich@example.invalid> |
|---|---|
| Date | 2020-07-17 22:37 +0000 |
| Subject | Re: Separate amps jacks on multimeters |
| Message-ID | <ret96j$3es$1@dont-email.me> |
| In reply to | #464 |
In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote: > On Fri, 17 Jul 2020 21:26:15 +0100, Rich <rich@example.invalid> wrote: >> As well, the user who'd leave the leads plugged into amps, and then >> try to measure voltage on car battery or other high current source >> is also just as likely to leave the range switch in the amps setting >> (after having measured current somewhere) and subsequently try to >> measure voltage. > > Nope. I pick up a multimeter and set it to what I'm about to > measure. Same way as I don't drive into my house because I left my > car in forward gear yesterday. Interesting.... Yet you said this yesterday: From: "Commander Kinsey" <CFKinsey@military.org.jp> Date: Thu, 16 Jul 2020 20:09:20 +0100 Message-ID: <op.0nu3hup8wdg98l@glass> ... I find it crazy that you can select volts and have the wires in the amps holes. ... I've broken a meter doing that, just measuring the voltage on a car battery. A £100 meter, but UNFUSED FFS! ... One aspect of "set it to what I'm about to measure" should normally include: "are the leads in the correct jacks".
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| From | "Commander Kinsey" <CFKinsey@military.org.jp> |
|---|---|
| Date | 2020-07-18 00:11 +0100 |
| Subject | Re: Separate amps jacks on multimeters |
| Message-ID | <op.0nw9dfu1wdg98l@glass> |
| In reply to | #467 |
On Fri, 17 Jul 2020 23:37:07 +0100, Rich <rich@example.invalid> wrote: > In sci.electronics.equipment Commander Kinsey <CFKinsey@military.org.jp> wrote: >> On Fri, 17 Jul 2020 21:26:15 +0100, Rich <rich@example.invalid> wrote: >>> As well, the user who'd leave the leads plugged into amps, and then >>> try to measure voltage on car battery or other high current source >>> is also just as likely to leave the range switch in the amps setting >>> (after having measured current somewhere) and subsequently try to >>> measure voltage. >> >> Nope. I pick up a multimeter and set it to what I'm about to >> measure. Same way as I don't drive into my house because I left my >> car in forward gear yesterday. > > Interesting.... > > Yet you said this yesterday: > > From: "Commander Kinsey" <CFKinsey@military.org.jp> > Date: Thu, 16 Jul 2020 20:09:20 +0100 > Message-ID: <op.0nu3hup8wdg98l@glass> > > ... > > I find it crazy that you can select volts and have the wires in the > amps holes. ... I've broken a meter doing that, just measuring the > voltage on a car battery. A £100 meter, but UNFUSED FFS! > > ... > > One aspect of "set it to what I'm about to measure" should normally > include: "are the leads in the correct jacks". No, because it's illogical to change two things to set one thing.
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| From | Ralph Mowery <rmowery28146@earthlink.net> |
|---|---|
| Date | 2020-07-17 18:07 -0400 |
| Subject | Re: Separate amps jacks on multimeters |
| Message-ID | <MPG.397beb2d3e0a941d989f6e@news.east.earthlink.net> |
| In reply to | #463 |
In article <ret1h6$stk$1@dont-email.me>, rich@example.invalid says... > > I suspect you would find changing the range switch while connected is > much more common than your response implies. Esp. for switching > up/down a range for meters that are not auto-ranging. > > >> 2) By having the amps jacks separate, the range switch itself does not > >> have to have contacts beefy enough to carry the current for the amps > >> settings. Remember, when measuring amps, the current being measured > >> flows *through* the meter itself. This would require very different > >> (and likely much more expensive) range switch contacts. > > > > Or a relay. > > Which also equates directly to added expense vs. having the user > themselves be that "relay". And for battery powered meters, shorter > battery life (due to the current consumed by the relay coil). > > It is also possible (this is a guess in my part) that the CAT ratings > specify separate amps jacks for an added safety factor of "user must > deliberately move lead to obtain short circuit through meter". > > As well, the user who'd leave the leads plugged into amps, and then try > to measure voltage on car battery or other high current source is also > just as likely to leave the range switch in the amps setting (after > having measured current somewhere) and subsequently try to measure > voltage. It is not possible to fully protect users who don't pay > attention from doing stupid things. Either they forget to unplug from > the amps jack, or they forget to switch away from the amps range, > either way they get a local fireworks display of their own doing. > > > I often leave the leads connected to a Simpson 260 and change voltage ranges. Where I worked there were so many wires in a conduit carrring 120 VAC control voltage it was difficult to tell if the voltage was 'real' or induced by the coupling. I found out that if I started on the 500 volt range and then switched to the 250 volt range if the meter pointer stayed in the same relative position I could then switch to the 50 volt range and the meter pointer would still be near the same relative position if the voltage was induced. If the pointer changed positions to follow the 120 VAC when going to the 250 volt scale the voltage was real. I doubt that the CAT rating requies seperate Amps positions for the leads. Fluke uses special fuses in their meters to get the CAT ratings. They do not have a seperate jack for the ohms settings either which is more likely where the meter would be set. Most of the time the circuit would have to be broken and the meter inserted to measuer amps. As you say it is impossiable to fully protect everyone from doing somethen forgetful or stupid, but having a $ 300 meter instead of a $ 5 dollar one goes a long ways. I do have a Fluke test meter that is purty much fool proof up to 600 volts and rated CAT 4. A T1000. It only measuers AC amps by passing a wire through the prongs. It does have a switch for voltage and ohms. I have on purpose set it to ohms and put it across a fuse in a 480 volt AC circuit to see if the fuse is good or bad. No problem to do this.
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| From | "Commander Kinsey" <CFKinsey@military.org.jp> |
|---|---|
| Date | 2020-07-17 23:31 +0100 |
| Subject | Re: Separate amps jacks on multimeters |
| Message-ID | <op.0nw7h4ytwdg98l@glass> |
| In reply to | #465 |
On Fri, 17 Jul 2020 23:07:43 +0100, Ralph Mowery <rmowery28146@earthlink.net> wrote: > In article <ret1h6$stk$1@dont-email.me>, rich@example.invalid says... >> >> I suspect you would find changing the range switch while connected is >> much more common than your response implies. Esp. for switching >> up/down a range for meters that are not auto-ranging. >> >> >> 2) By having the amps jacks separate, the range switch itself does not >> >> have to have contacts beefy enough to carry the current for the amps >> >> settings. Remember, when measuring amps, the current being measured >> >> flows *through* the meter itself. This would require very different >> >> (and likely much more expensive) range switch contacts. >> > >> > Or a relay. >> >> Which also equates directly to added expense vs. having the user >> themselves be that "relay". And for battery powered meters, shorter >> battery life (due to the current consumed by the relay coil). >> >> It is also possible (this is a guess in my part) that the CAT ratings >> specify separate amps jacks for an added safety factor of "user must >> deliberately move lead to obtain short circuit through meter". >> >> As well, the user who'd leave the leads plugged into amps, and then try >> to measure voltage on car battery or other high current source is also >> just as likely to leave the range switch in the amps setting (after >> having measured current somewhere) and subsequently try to measure >> voltage. It is not possible to fully protect users who don't pay >> attention from doing stupid things. Either they forget to unplug from >> the amps jack, or they forget to switch away from the amps range, >> either way they get a local fireworks display of their own doing. > > I often leave the leads connected to a Simpson 260 and change voltage > ranges. Where I worked there were so many wires in a conduit carrring > 120 VAC control voltage it was difficult to tell if the voltage was > 'real' or induced by the coupling. I found out that if I started on the > 500 volt range and then switched to the 250 volt range if the meter > pointer stayed in the same relative position I could then switch to the > 50 volt range and the meter pointer would still be near the same > relative position if the voltage was induced. If the pointer changed > positions to follow the 120 VAC when going to the 250 volt scale the > voltage was real. Better to use something that draws bit of current, like one of those screwdrivers that lights a neon through your capacitance. > I doubt that the CAT rating requies seperate Amps positions for the > leads. Fluke uses special fuses in their meters to get the CAT ratings. > They do not have a seperate jack for the ohms settings either which is > more likely where the meter would be set. Most of the time the > circuit would have to be broken and the meter inserted to measuer amps. > > As you say it is impossiable to fully protect everyone from doing > somethen forgetful or stupid, but having a $ 300 meter instead of a $ 5 > dollar one goes a long ways. > > I do have a Fluke test meter that is purty much fool proof up to 600 > volts and rated CAT 4. A T1000. It only measuers AC amps by passing a > wire through the prongs. It does have a switch for voltage and ohms. I > have on purpose set it to ohms and put it across a fuse in a 480 volt AC > circuit to see if the fuse is good or bad. No problem to do this. With a bad fuse it doesn't blow up?
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| From | Ralph Mowery <rmowery28146@earthlink.net> |
|---|---|
| Date | 2020-07-17 19:10 -0400 |
| Subject | Re: Separate amps jacks on multimeters |
| Message-ID | <MPG.397bf9de45f03b8d989f6f@news.east.earthlink.net> |
| In reply to | #466 |
In article <op.0nw7h4ytwdg98l@glass>, CFKinsey@military.org.jp says... > I do have a Fluke test meter that is purty much fool proof up to 600 > > volts and rated CAT 4. A T1000. It only measuers AC amps by passing a > > wire through the prongs. It does have a switch for voltage and ohms. I > > have on purpose set it to ohms and put it across a fuse in a 480 volt AC > > circuit to see if the fuse is good or bad. No problem to do this. > > With a bad fuse it doesn't blow up? > > No it does not . It is designed to protect its self from voltage on the ohms scale. They are only about $ 130 Even better is a quick tester by Fluke. it has 2 leads and about 8 or so leds on it. Both it and the T1000 look similar to bannanas, even yellow in color. The 2nd tester is fully automatic. Connect the two leads to anything under 600 or so volts. If voltage, the leds light up , the more for more voltage. Anoter is for AC or DC. If there is less than about 200 ohms and no voltage, there is a led and buzzer for that. About as fool proof as they make it for quick tests.
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| From | "Commander Kinsey" <CFKinsey@military.org.jp> |
|---|---|
| Date | 2020-07-18 00:18 +0100 |
| Subject | Re: Separate amps jacks on multimeters |
| Message-ID | <op.0nw9prwrwdg98l@glass> |
| In reply to | #468 |
On Sat, 18 Jul 2020 00:10:49 +0100, Ralph Mowery <rmowery28146@earthlink.net> wrote: > In article <op.0nw7h4ytwdg98l@glass>, CFKinsey@military.org.jp says... >> I do have a Fluke test meter that is purty much fool proof up to 600 >> > volts and rated CAT 4. A T1000. It only measuers AC amps by passing a >> > wire through the prongs. It does have a switch for voltage and ohms. I >> > have on purpose set it to ohms and put it across a fuse in a 480 volt AC >> > circuit to see if the fuse is good or bad. No problem to do this. >> >> With a bad fuse it doesn't blow up? >> >> > > No it does not . It is designed to protect its self from voltage on the > ohms scale. They are only about $ 130 Howe does it measure ohms and distinguish its own current from the current from the circuit? That's if you're testing a DC circuit. > Even better is a quick tester by Fluke. it has 2 leads and about 8 or > so leds on it. Both it and the T1000 look similar to bannanas, even > yellow in color. The 2nd tester is fully automatic. Connect the two > leads to anything under 600 or so volts. If voltage, the leds light up > , the more for more voltage. Anoter is for AC or DC. If there is less > than about 200 ohms and no voltage, there is a led and buzzer for that. > > About as fool proof as they make it for quick tests. Does it check for current if there's no voltage?
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| From | Ralph Mowery <rmowery28146@earthlink.net> |
|---|---|
| Date | 2020-07-17 19:30 -0400 |
| Subject | Re: Separate amps jacks on multimeters |
| Message-ID | <MPG.397bfe9850cb9a92989f71@news.east.earthlink.net> |
| In reply to | #470 |
In article <op.0nw9prwrwdg98l@glass>, CFKinsey@military.org.jp says... > > > About as fool proof as they make it for quick tests. > > Does it check for current if there's no voltage? > > Just how can there be curent if there is no voltage ? There is no current by the leads, but works like a clamp on meter to check for AC Current. Does not do DC current. There can be voltage but no current.
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| From | "Commander Kinsey" <CFKinsey@military.org.jp> |
|---|---|
| Date | 2020-07-28 22:16 +0100 |
| Subject | Re: Separate amps jacks on multimeters |
| Message-ID | <op.0ohhd5d7wdg98l@glass> |
| In reply to | #472 |
On Sat, 18 Jul 2020 00:30:22 +0100, Ralph Mowery <rmowery28146@earthlink.net> wrote: > In article <op.0nw9prwrwdg98l@glass>, CFKinsey@military.org.jp says... >> >> > About as fool proof as they make it for quick tests. >> >> Does it check for current if there's no voltage? > > Just how can there be curent if there is no voltage ? > > There is no current by the leads, but works like a clamp on meter to > check for AC Current. Does not do DC current. > > There can be voltage but no current. I meant does it automatically work out if you want to test for current or voltage?
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| From | Cydrome Leader <presence@MUNGEpanix.com> |
|---|---|
| Date | 2020-07-22 04:24 +0000 |
| Subject | Re: Separate amps jacks on multimeters |
| Message-ID | <rf8f20$brr$2@reader1.panix.com> |
| In reply to | #468 |
In sci.electronics.basics Ralph Mowery <rmowery28146@earthlink.net> wrote: > In article <op.0nw7h4ytwdg98l@glass>, CFKinsey@military.org.jp says... >> I do have a Fluke test meter that is purty much fool proof up to 600 >> > volts and rated CAT 4. A T1000. It only measuers AC amps by passing a >> > wire through the prongs. It does have a switch for voltage and ohms. I >> > have on purpose set it to ohms and put it across a fuse in a 480 volt AC >> > circuit to see if the fuse is good or bad. No problem to do this. >> >> With a bad fuse it doesn't blow up? >> >> > > No it does not . It is designed to protect its self from voltage on the > ohms scale. They are only about $ 130 > > Even better is a quick tester by Fluke. it has 2 leads and about 8 or > so leds on it. Both it and the T1000 look similar to bannanas, even > yellow in color. The 2nd tester is fully automatic. Connect the two > leads to anything under 600 or so volts. If voltage, the leds light up > , the more for more voltage. Anoter is for AC or DC. If there is less > than about 200 ohms and no voltage, there is a led and buzzer for that. > > About as fool proof as they make it for quick tests. Hmm, Remeber those neon voltage testers with two leads and the bizarre shirt pocket clip? I had one go out on me, showed no voltage when there was some. Whoops. Now I use one of those ground/wiring testers. I figure it will still light up if one neon indicator fails.
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| From | Ralph Mowery <rmowery28146@earthlink.net> |
|---|---|
| Date | 2020-07-22 12:28 -0400 |
| Subject | Re: Separate amps jacks on multimeters |
| Message-ID | <MPG.398233321aa85b7c989f7c@news.east.earthlink.net> |
| In reply to | #478 |
In article <rf8f20$brr$2@reader1.panix.com>, presence@MUNGEpanix.com says... > > Hmm, Remeber those neon voltage testers with two leads and the bizarre > shirt pocket clip? I had one go out on me, showed no voltage when there > was some. Whoops. > > Now I use one of those ground/wiring testers. I figure it will still light > up if one neon indicator fails. > > > Yes, I used one very often. One learns to put the leads across a source that should have voltage on it to see if the neon bulb lights up, then put it to the point to test and if the neon does not light up, go back to a point that should have voltage on it. Bad thing about where I worked there was so many wires in conduit that the neon would light up even if there was no 'real' voltage on the wire. Just induced voltage that if put under much of a load at all will seem to diaspear. It is still enough to shock the crap out of you, especially if wet with sweat.
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| From | Ralph Mowery <rmowery28146@earthlink.net> |
|---|---|
| Date | 2020-07-17 19:25 -0400 |
| Subject | Re: Separate amps jacks on multimeters |
| Message-ID | <MPG.397bfd7565877484989f70@news.east.earthlink.net> |
| In reply to | #466 |
In article <op.0nw7h4ytwdg98l@glass>, CFKinsey@military.org.jp says... > > > I do have a Fluke test meter that is purty much fool proof up to 600 > > volts and rated CAT 4. A T1000. It only measuers AC amps by passing a > > wire through the prongs. It does have a switch for voltage and ohms. I > > have on purpose set it to ohms and put it across a fuse in a 480 volt AC > > circuit to see if the fuse is good or bad. No problem to do this. > > With a bad fuse it doesn't blow up? > > No, it is designed to protect its self.
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| From | Cydrome Leader <presence@MUNGEpanix.com> |
|---|---|
| Date | 2020-07-22 04:20 +0000 |
| Subject | Re: Separate amps jacks on multimeters |
| Message-ID | <rf8eq6$brr$1@reader1.panix.com> |
| In reply to | #465 |
In sci.electronics.basics Ralph Mowery <rmowery28146@earthlink.net> wrote: > In article <ret1h6$stk$1@dont-email.me>, rich@example.invalid says... >> >> I suspect you would find changing the range switch while connected is >> much more common than your response implies. Esp. for switching >> up/down a range for meters that are not auto-ranging. >> >> >> 2) By having the amps jacks separate, the range switch itself does not >> >> have to have contacts beefy enough to carry the current for the amps >> >> settings. Remember, when measuring amps, the current being measured >> >> flows *through* the meter itself. This would require very different >> >> (and likely much more expensive) range switch contacts. >> > >> > Or a relay. >> >> Which also equates directly to added expense vs. having the user >> themselves be that "relay". And for battery powered meters, shorter >> battery life (due to the current consumed by the relay coil). >> >> It is also possible (this is a guess in my part) that the CAT ratings >> specify separate amps jacks for an added safety factor of "user must >> deliberately move lead to obtain short circuit through meter". >> >> As well, the user who'd leave the leads plugged into amps, and then try >> to measure voltage on car battery or other high current source is also >> just as likely to leave the range switch in the amps setting (after >> having measured current somewhere) and subsequently try to measure >> voltage. It is not possible to fully protect users who don't pay >> attention from doing stupid things. Either they forget to unplug from >> the amps jack, or they forget to switch away from the amps range, >> either way they get a local fireworks display of their own doing. >> >> >> > > I often leave the leads connected to a Simpson 260 and change voltage > ranges. Where I worked there were so many wires in a conduit carrring > 120 VAC control voltage it was difficult to tell if the voltage was > 'real' or induced by the coupling. I found out that if I started on the > 500 volt range and then switched to the 250 volt range if the meter > pointer stayed in the same relative position I could then switch to the > 50 volt range and the meter pointer would still be near the same > relative position if the voltage was induced. If the pointer changed > positions to follow the 120 VAC when going to the 250 volt scale the > voltage was real. The simpson meters are interesting in that they have as many jacks as they they positions on the switch. You really need to move the leads around all the time to do anything. I guest it makes you think, a little. I did catch myself reading the ohms range wrong though recently. > I doubt that the CAT rating requies seperate Amps positions for the > leads. Fluke uses special fuses in their meters to get the CAT ratings. > They do not have a seperate jack for the ohms settings either which is > more likely where the meter would be set. Most of the time the > circuit would have to be broken and the meter inserted to measuer amps. > > As you say it is impossiable to fully protect everyone from doing > somethen forgetful or stupid, but having a $ 300 meter instead of a $ 5 > dollar one goes a long ways. > > I do have a Fluke test meter that is purty much fool proof up to 600 > volts and rated CAT 4. A T1000. It only measuers AC amps by passing a > wire through the prongs. It does have a switch for voltage and ohms. I > have on purpose set it to ohms and put it across a fuse in a 480 volt AC > circuit to see if the fuse is good or bad. No problem to do this. I just got one of those clamp current multimeters. I noticed some glaring limitations vs the full out Fluke 87 V, but at the same time, it's way more "idiot-proof". The current ranges, even for DC at only available though the current clamp. It's just not possible to short anything out with the test probes. The downside (not really surprising) is no low current ranges. Ok fine. The input impedance is pretty low at 1Meg as well, but for poking at line voltage wiring, this is fine. Again, no matter what range you are set it, it appears to be impossible to blow up the meter as it has no low resistance across the leads modes. The ohms range seems to max out at 40k or something surprisibly low like that, again, no big deal for prodding at lighting circuits or an outlet, or some 24 volt circuit. Getting all sorts of wonky reading with the banana jack type K thermocouple though. It seems the meter has an internal thermometer and it compares to the junction at the end of the probe. Not really sure how that all works and how the temperatures of the banana jacks affect things as they are not the special metals in the leads of the probe. I know with normal process controllers, and deviation of the correct connector or metals used will result in really strange readings.
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