Question for old-timers re: Simpson meters
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From: Jim Yanik on 16 Jan 2010 18:38 "Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in news:00b076d3$0$16796$c3e8da3(a)news.astraweb.com: > "Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_(a)charter.net> wrote in > message news:1xk4n.6308$%P5.991(a)newsfe21.iad... >> Mark Zacharias wrote: >> >>> "Dave M" <dgminala4444(a)mediacombb.net> wrote in message >>> news:LcydnZhaWvohgMzWnZ2dnUVZ_o2dnZ2d(a)giganews.com... >>> >>>> Jim Yanik wrote: >>>> >>>>> "Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in >>>>> news:00c8f14f$0$1584$c3e8da3(a)news.astraweb.com: >>>>> >>>>>> "Jim Yanik" <jyanik(a)abuse.gov> wrote in message >>>>>> news:Xns9D005EBA3EB83jyaniklocalnetcom(a)216.168.3.44... >>>>>> >>>>>>> "Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in >>>>>>> news:003beb0d$0$2118$c3e8da3(a)news.astraweb.com: >>>>>>> >>>>>>>> Hi, >>>>>>>> >>>>>>>> As some of the guys here know, I presently collect old analog >>>>>>>> multimeters. >>>>>>>> >>>>>>>> I recall a picture I saw several years ago of a "wall" of >>>>>>>> Simpson meters - maybe 50 or more, used to demonstrate >>>>>>>> reliability. They were all being pulsed with DC of perhaps 0.5 >>>>>>>> hz or so for years on end and none had failed. >>>>>>> >>>>>>> >>>>>>> that's not surprising; >>>>>>> the meter movements are very simple and sealed from >>>>>>> contamination. there's not much to fail,especially if you're not >>>>>>> transporting them. >>>>>>> >>>>>>> the batteries leaking or resistors going out of tolerance are >>>>>>> the biggest problems with Simpson meters,aside from being >>>>>>> dropped. >>>>>>> >>>>>>>> >>>>>>>> Anybody remember this and where can I get a JPG of this, and >>>>>>>> maybe a link to the info? >>>>>>>> >>>>>>>> I've tried Google images etc no luck. >>>>>>>> >>>>>>>> >>>>>>>> Mark Z. >>>>>>>> >>>>>>>> -- >>>>>>> >>>>>>> Jim Yanik >>>>>>> jyanik >>>>>>> at >>>>>>> localnet >>>>>>> dot com >>>>>> >>>>>> >>>>>> >>>>>> Not surprising except perhaps considering mechanical issues - >>>>>> bearings, solder - to-coil connections, spring and/or taut-band >>>>>> failure, etc. As I recall, they were running this way for maybe >>>>>> over 20 years. >>>>>> >>>>>> They may have been naked meter movements and not complete VOM's. >>>>>> >>>>>> Like to have that picture, though... >>>>>> >>>>>> Mark Z. >>>>>> >>>>>> >>>>> >>>>> those meters on the wall were likely left in one switch position >>>>> and thus not any different than a "naked meter movement" with a >>>>> resistor in series to measure voltage instead of current. >>>>> >>>>> BTW,I still have my Simpson 270-3 VOM. Works great. >>>> >>>> >>>> I, too, still have my 260-3 that I bought from Allied Electronics >>>> in 1965, while serving in the Navy. It's not totally original, >>>> since I replaced the original meter movement in the late 60s with a >>>> taut band movement from a damaged instrument, and later selected >>>> the range resistors to improve the accuracy. Since then, it has >>>> served flawlessly, and on the last calibration, was still +/- 1% on >>>> all DC voltage and current ranges. AC and resistance ranges were a >>>> bit less accurate, but still well within specs. >>>> In all, it was $65 well spent.. >>>> >>>> -- >>>> David >>>> dgminala at mediacombb dot net >>>> >>>> >>>> >>> >>> Models 260-3 and later have internal adjustments which can obtain >>> accuracy to a very high degree. The 10 volt range suffers a bit at >>> full scale but I adjust mine for best accuracy in the 5 to 5.6 volt >>> range, where small differences can be huge in modern equipment. >>> Sometimes you just have to use a good digital meter though, and I >>> have several of them as well. Yamaha receivers use protection >>> circuits where the difference between 1.2 and 1.4 volts, for >>> example, can be critical. >>> >>> Trouble is we often take the readings of a digital as "gospel". >>> Recently a co-workers' cheap digital was discovered to have >>> approximately a 50% error when we were reading a Vsus line in a >>> plasma. We were trying to find why the reading was 295 volts instead >>> of the desired 195. After trying a different power supply board, it >>> was discovered the multimeter had come up lame. >>> >>> Mark Z. >> You're suppose to calibrate analog scales at 75% of their deflection. >> Sez who? >> >> > > That's a pretty general statement... but sounds like a good idea in > many cases. > I have an RCA WV-38A one adjustment of which is for 1 mA full scale. > > Mark Z. > > Simpson meter movements are usually 50uA FS,but I recall one that was less than that. A BIG meter. One thing to worry about with analog meters is their input Z. It varys with range. digital DMMs don't,and usually have a higher Z. -- Jim Yanik jyanik at localnet dot com
From: Mark Zacharias on 16 Jan 2010 21:56 "Jim Yanik" <jyanik(a)abuse.gov> wrote in message news:Xns9D02BDB4E1AA6jyaniklocalnetcom(a)216.168.3.44... > "Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in > news:00b076d3$0$16796$c3e8da3(a)news.astraweb.com: > >> "Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_(a)charter.net> wrote in >> message news:1xk4n.6308$%P5.991(a)newsfe21.iad... >>> Mark Zacharias wrote: >>> >>>> "Dave M" <dgminala4444(a)mediacombb.net> wrote in message >>>> news:LcydnZhaWvohgMzWnZ2dnUVZ_o2dnZ2d(a)giganews.com... >>>> >>>>> Jim Yanik wrote: >>>>> >>>>>> "Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in >>>>>> news:00c8f14f$0$1584$c3e8da3(a)news.astraweb.com: >>>>>> >>>>>>> "Jim Yanik" <jyanik(a)abuse.gov> wrote in message >>>>>>> news:Xns9D005EBA3EB83jyaniklocalnetcom(a)216.168.3.44... >>>>>>> >>>>>>>> "Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in >>>>>>>> news:003beb0d$0$2118$c3e8da3(a)news.astraweb.com: >>>>>>>> >>>>>>>>> Hi, >>>>>>>>> >>>>>>>>> As some of the guys here know, I presently collect old analog >>>>>>>>> multimeters. >>>>>>>>> >>>>>>>>> I recall a picture I saw several years ago of a "wall" of >>>>>>>>> Simpson meters - maybe 50 or more, used to demonstrate >>>>>>>>> reliability. They were all being pulsed with DC of perhaps 0.5 >>>>>>>>> hz or so for years on end and none had failed. >>>>>>>> >>>>>>>> >>>>>>>> that's not surprising; >>>>>>>> the meter movements are very simple and sealed from >>>>>>>> contamination. there's not much to fail,especially if you're not >>>>>>>> transporting them. >>>>>>>> >>>>>>>> the batteries leaking or resistors going out of tolerance are >>>>>>>> the biggest problems with Simpson meters,aside from being >>>>>>>> dropped. >>>>>>>> >>>>>>>>> >>>>>>>>> Anybody remember this and where can I get a JPG of this, and >>>>>>>>> maybe a link to the info? >>>>>>>>> >>>>>>>>> I've tried Google images etc no luck. >>>>>>>>> >>>>>>>>> >>>>>>>>> Mark Z. >>>>>>>>> >>>>>>>>> -- >>>>>>>> >>>>>>>> Jim Yanik >>>>>>>> jyanik >>>>>>>> at >>>>>>>> localnet >>>>>>>> dot com >>>>>>> >>>>>>> >>>>>>> >>>>>>> Not surprising except perhaps considering mechanical issues - >>>>>>> bearings, solder - to-coil connections, spring and/or taut-band >>>>>>> failure, etc. As I recall, they were running this way for maybe >>>>>>> over 20 years. >>>>>>> >>>>>>> They may have been naked meter movements and not complete VOM's. >>>>>>> >>>>>>> Like to have that picture, though... >>>>>>> >>>>>>> Mark Z. >>>>>>> >>>>>>> >>>>>> >>>>>> those meters on the wall were likely left in one switch position >>>>>> and thus not any different than a "naked meter movement" with a >>>>>> resistor in series to measure voltage instead of current. >>>>>> >>>>>> BTW,I still have my Simpson 270-3 VOM. Works great. >>>>> >>>>> >>>>> I, too, still have my 260-3 that I bought from Allied Electronics >>>>> in 1965, while serving in the Navy. It's not totally original, >>>>> since I replaced the original meter movement in the late 60s with a >>>>> taut band movement from a damaged instrument, and later selected >>>>> the range resistors to improve the accuracy. Since then, it has >>>>> served flawlessly, and on the last calibration, was still +/- 1% on >>>>> all DC voltage and current ranges. AC and resistance ranges were a >>>>> bit less accurate, but still well within specs. >>>>> In all, it was $65 well spent.. >>>>> >>>>> -- >>>>> David >>>>> dgminala at mediacombb dot net >>>>> >>>>> >>>>> >>>> >>>> Models 260-3 and later have internal adjustments which can obtain >>>> accuracy to a very high degree. The 10 volt range suffers a bit at >>>> full scale but I adjust mine for best accuracy in the 5 to 5.6 volt >>>> range, where small differences can be huge in modern equipment. >>>> Sometimes you just have to use a good digital meter though, and I >>>> have several of them as well. Yamaha receivers use protection >>>> circuits where the difference between 1.2 and 1.4 volts, for >>>> example, can be critical. >>>> >>>> Trouble is we often take the readings of a digital as "gospel". >>>> Recently a co-workers' cheap digital was discovered to have >>>> approximately a 50% error when we were reading a Vsus line in a >>>> plasma. We were trying to find why the reading was 295 volts instead >>>> of the desired 195. After trying a different power supply board, it >>>> was discovered the multimeter had come up lame. >>>> >>>> Mark Z. >>> You're suppose to calibrate analog scales at 75% of their deflection. >>> > > > Sez who? > >>> >>> >> >> That's a pretty general statement... but sounds like a good idea in >> many cases. >> I have an RCA WV-38A one adjustment of which is for 1 mA full scale. >> >> Mark Z. >> >> > > Simpson meter movements are usually 50uA FS,but I recall one that was less > than that. A BIG meter. > > One thing to worry about with analog meters is their input Z. > It varys with range. digital DMMs don't,and usually have a higher Z. > > -- > Jim Yanik > jyanik > at > localnet > dot com I was having a discussion about that with a glass-head buddy at work. He opined that a regular VOM would load down a plate voltage reading if there is a high value plate resistor, so one should use a DMM instead. Trouble with that was, a 20 kOhm/volt meter on a 1000 volt range, which would be the range often used in this situation, adds up to 20 meg - double the input resistance of a typical DMM. Obviously grid voltage would be another matter... Mark Z.
From: Mark Zacharias on 16 Jan 2010 22:03 "Jim Yanik" <jyanik(a)abuse.gov> wrote in message news:Xns9D02BDB4E1AA6jyaniklocalnetcom(a)216.168.3.44... > "Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in > news:00b076d3$0$16796$c3e8da3(a)news.astraweb.com: > >> "Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_(a)charter.net> wrote in >> message news:1xk4n.6308$%P5.991(a)newsfe21.iad... >>> Mark Zacharias wrote: >>> >>>> "Dave M" <dgminala4444(a)mediacombb.net> wrote in message >>>> news:LcydnZhaWvohgMzWnZ2dnUVZ_o2dnZ2d(a)giganews.com... >>>> >>>>> Jim Yanik wrote: >>>>> >>>>>> "Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in >>>>>> news:00c8f14f$0$1584$c3e8da3(a)news.astraweb.com: >>>>>> >>>>>>> "Jim Yanik" <jyanik(a)abuse.gov> wrote in message >>>>>>> news:Xns9D005EBA3EB83jyaniklocalnetcom(a)216.168.3.44... >>>>>>> >>>>>>>> "Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in >>>>>>>> news:003beb0d$0$2118$c3e8da3(a)news.astraweb.com: >>>>>>>> >>>>>>>>> Hi, >>>>>>>>> >>>>>>>>> As some of the guys here know, I presently collect old analog >>>>>>>>> multimeters. >>>>>>>>> >>>>>>>>> I recall a picture I saw several years ago of a "wall" of >>>>>>>>> Simpson meters - maybe 50 or more, used to demonstrate >>>>>>>>> reliability. They were all being pulsed with DC of perhaps 0.5 >>>>>>>>> hz or so for years on end and none had failed. >>>>>>>> >>>>>>>> >>>>>>>> that's not surprising; >>>>>>>> the meter movements are very simple and sealed from >>>>>>>> contamination. there's not much to fail,especially if you're not >>>>>>>> transporting them. >>>>>>>> >>>>>>>> the batteries leaking or resistors going out of tolerance are >>>>>>>> the biggest problems with Simpson meters,aside from being >>>>>>>> dropped. >>>>>>>> >>>>>>>>> >>>>>>>>> Anybody remember this and where can I get a JPG of this, and >>>>>>>>> maybe a link to the info? >>>>>>>>> >>>>>>>>> I've tried Google images etc no luck. >>>>>>>>> >>>>>>>>> >>>>>>>>> Mark Z. >>>>>>>>> >>>>>>>>> -- >>>>>>>> >>>>>>>> Jim Yanik >>>>>>>> jyanik >>>>>>>> at >>>>>>>> localnet >>>>>>>> dot com >>>>>>> >>>>>>> >>>>>>> >>>>>>> Not surprising except perhaps considering mechanical issues - >>>>>>> bearings, solder - to-coil connections, spring and/or taut-band >>>>>>> failure, etc. As I recall, they were running this way for maybe >>>>>>> over 20 years. >>>>>>> >>>>>>> They may have been naked meter movements and not complete VOM's. >>>>>>> >>>>>>> Like to have that picture, though... >>>>>>> >>>>>>> Mark Z. >>>>>>> >>>>>>> >>>>>> >>>>>> those meters on the wall were likely left in one switch position >>>>>> and thus not any different than a "naked meter movement" with a >>>>>> resistor in series to measure voltage instead of current. >>>>>> >>>>>> BTW,I still have my Simpson 270-3 VOM. Works great. >>>>> >>>>> >>>>> I, too, still have my 260-3 that I bought from Allied Electronics >>>>> in 1965, while serving in the Navy. It's not totally original, >>>>> since I replaced the original meter movement in the late 60s with a >>>>> taut band movement from a damaged instrument, and later selected >>>>> the range resistors to improve the accuracy. Since then, it has >>>>> served flawlessly, and on the last calibration, was still +/- 1% on >>>>> all DC voltage and current ranges. AC and resistance ranges were a >>>>> bit less accurate, but still well within specs. >>>>> In all, it was $65 well spent.. >>>>> >>>>> -- >>>>> David >>>>> dgminala at mediacombb dot net >>>>> >>>>> >>>>> >>>> >>>> Models 260-3 and later have internal adjustments which can obtain >>>> accuracy to a very high degree. The 10 volt range suffers a bit at >>>> full scale but I adjust mine for best accuracy in the 5 to 5.6 volt >>>> range, where small differences can be huge in modern equipment. >>>> Sometimes you just have to use a good digital meter though, and I >>>> have several of them as well. Yamaha receivers use protection >>>> circuits where the difference between 1.2 and 1.4 volts, for >>>> example, can be critical. >>>> >>>> Trouble is we often take the readings of a digital as "gospel". >>>> Recently a co-workers' cheap digital was discovered to have >>>> approximately a 50% error when we were reading a Vsus line in a >>>> plasma. We were trying to find why the reading was 295 volts instead >>>> of the desired 195. After trying a different power supply board, it >>>> was discovered the multimeter had come up lame. >>>> >>>> Mark Z. >>> You're suppose to calibrate analog scales at 75% of their deflection. >>> > > > Sez who? > >>> >>> >> >> That's a pretty general statement... but sounds like a good idea in >> many cases. >> I have an RCA WV-38A one adjustment of which is for 1 mA full scale. >> >> Mark Z. >> >> > > Simpson meter movements are usually 50uA FS,but I recall one that was less > than that. A BIG meter. > > One thing to worry about with analog meters is their input Z. > It varys with range. digital DMMs don't,and usually have a higher Z. > > -- > Jim Yanik > jyanik > at > localnet > dot com Yes, nominally one adjusts the swamp resistor for 50 uA at full scale, but I'm not afraid to fudge that a little to get the overall accuracy where I want it. I use these things to measure voltage, rarely current, and if I am measuring current, it's only going to be measuring battery charge current or the like, not a critical application. Mark Z.
From: Jim Yanik on 17 Jan 2010 00:46 "Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in news:00017320$0$2285$c3e8da3(a)news.astraweb.com: > "Jim Yanik" <jyanik(a)abuse.gov> wrote in message > news:Xns9D02BDB4E1AA6jyaniklocalnetcom(a)216.168.3.44... >> One thing to worry about with analog meters is their input Z. >> It varys with range. digital DMMs don't,and usually have a higher Z. >> >> -- >> Jim Yanik >> jyanik >> at >> localnet >> dot com > > > I was having a discussion about that with a glass-head buddy at work. > He opined that a regular VOM would load down a plate voltage reading > if there is a high value plate resistor, so one should use a DMM > instead. Trouble with that was, a 20 kOhm/volt meter on a 1000 volt > range, which would be the range often used in this situation, adds up > to 20 meg - double the input resistance of a typical DMM. > > Obviously grid voltage would be another matter... > > Mark Z. > > I made a HV probe for my 10Meg-Z DMM,gives me 100MegZ but I have to use a lower range or divide by 10. But how many tube circuits do you encouter these days? -- Jim Yanik jyanik at localnet dot com
From: Jim Yanik on 17 Jan 2010 00:50
"Mark Zacharias" <mark_zacharias(a)sbclobal.net> wrote in news:000174b0$0$2281$c3e8da3(a)news.astraweb.com: > "Jim Yanik" <jyanik(a)abuse.gov> wrote in message > news:Xns9D02BDB4E1AA6jyaniklocalnetcom(a)216.168.3.44... >> Simpson meter movements are usually 50uA FS,but I recall one that was >> less than that. A BIG meter. >> >> One thing to worry about with analog meters is their input Z. >> It varys with range. digital DMMs don't,and usually have a higher Z. >> >> -- >> Jim Yanik >> jyanik >> at >> localnet >> dot com > > > Yes, nominally one adjusts the swamp resistor for 50 uA at full scale, > but I'm not afraid to fudge that a little to get the overall accuracy > where I want it. I use these things to measure voltage, rarely > current, and if I am measuring current, it's only going to be > measuring battery charge current or the like, not a critical > application. > > Mark Z. > > The thing is,the FIRST cal check/adjustment you make is the basic 50ua setting,then you go on to check the other ranges and make other adjustments. That 50ua cal adjust affects ALL the other ranges and modes. adjusting it to optimize other ranges may hide an out of tolerance resistor. -- Jim Yanik jyanik at localnet dot com |