Identification help of soviet passive component - Page 1
Forum section: electronics / general

author: Vtile
author_rank: Super Contributor
timestamp: January 29, 2022, 09:38:12 pm
content: Hi.I do have a handfull of these components (see pictures) past 20+ years or so. I again found the old can I have them in.My problem is that I just can't identify or measure them. The resistance seems to be over 1Gohms and even the capacitance seems to be that small that I do not have any even close to reliable measuring device in my disposal. I just were measuring roughly 0.5 pA with 10Vdc exidation voltage, but again I'm pushing my equipment on its limit.Anyone have idea, I have no other idea than that they are from old Riga radio factory, by the story told when they were handed to me.

author: rob77
author_rank: Super Contributor
timestamp: January 29, 2022, 09:41:49 pm
content: that should be a capacitor.. probably you can't measure because it's only 15pF

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2022, 09:52:55 pm
content: Those are capacitors and they are not great. Their real value is in the silver and other precious metal contents. If you can get a lot of them, they pay well. Their plates are made out of pure silver.

author: BrokenYugo
author_rank: Super Contributor
timestamp: January 29, 2022, 09:56:57 pm
content: 15pf 10%? Parallel the device in question with 100pf if you don't have anything that reads low enough.

author: Vtile
author_rank: Super Contributor
timestamp: January 29, 2022, 10:01:16 pm
content: Ok. Thanks.That is what I were thinking - since they do seem to have less reactance than resistance - but could not verify properly.A trash more or less, I have a about a big handfull of those so not worth to try sell / salvage.

author: Vovk_Z
author_rank: Super Contributor
timestamp: January 29, 2022, 10:02:12 pm
content: It is a capacitor. 15 pF +-10 pF (with all temperature range).Temperature coefficient is not larger than minus 1500 ppm.

author: Vtile
author_rank: Super Contributor
timestamp: January 29, 2022, 10:08:18 pm
content: Quote from: BrokenYugo on January 29, 2022, 09:56:57 pmI think I did years ago measure them with classic sine generator & scope setup with series resistor, but again all I remember that phase shift was that low that it could have been the wires in measuring setup, then I did throw the can again at the bottom storage box.

author: Vtile
author_rank: Super Contributor
timestamp: January 29, 2022, 10:18:58 pm
content: Quote from: Vovk_Z on January 29, 2022, 10:02:12 pmThank you. Is the M1500 marking for that "minus 1500ppm" I would assume -1500ppm/K ?

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2022, 10:30:02 pm
content: Quote from: Vtile on January 29, 2022, 10:18:58 pmCorrect. It is ppm/C officially, but it is the same thing, of course.-1500 is one of the worst in the series. I think the worst ones ever made were -2000.

author: TimFox
author_rank: Super Contributor
timestamp: January 29, 2022, 10:39:10 pm
content: Negative temperature co-efficient ceramic capacitors are not necessarily "bad" (although they do tend to have worse loss than NP0/C0G). They were often used for temperature compensation in oscillators, etc., back in the day.An example of US standard notation is "N750" for -750 ppm/K or -750/Co.

author: Vtile
author_rank: Super Contributor
timestamp: January 29, 2022, 10:43:20 pm
content: Quote from: ataradov on January 29, 2022, 10:30:02 pmYep, seems definitely something that can be found from cheap pocket radio.Case closed finally. Thanks everyone and especially to you ataradov and Vovk_Z for details.

author: ataradov
author_rank: Super Contributor
timestamp: January 29, 2022, 10:44:05 pm
content: Sure, there may be uses for them.One cool feature of those small value tube capacitors is that you can "tune" them. If you wind a coil of wire around its body and solder one of the ends to a pin, you can increase the capacitance by a few pF. I've seen this done in amateur radio.

author: Vtile
author_rank: Super Contributor
timestamp: January 29, 2022, 11:20:56 pm
content: So many simultaneus responses...TimFox thanks about note of tempco compensation, I do not work with oscillators in my electronic hobby so most of the time nanofarads are the lowest I do go.The tuning is also interesting idea, I do wonder what kind of self oscillator it would be if wound to be a toroid over capacitor with fine enamel wire.