1960-1970 capacitors still working?! - Page 1
Forum section: electronics / general

author: wwjd1924
author_rank: Contributor
timestamp: January 24, 2022, 01:32:44 pm
content: I bought 22 kilo's of vintage electronics from an former Philips employee.A lot of vintage IC's in ceramic and also a bag full of large electrolytic capacitors.I measures a few of them and they seem fine?Are they usable, is testing them with my Peak LCR45 and ERS meter enough to determine that?If so, I want to sell them on Ebay but I don't want to sell bad stuff of course...Thanks!

author: Siwastaja
author_rank: Super Contributor
timestamp: January 24, 2022, 01:50:14 pm
content: Usually they work but it's hit-or-miss. Slowly charging them up with a series resistor to limit current helps reform the insulating oxide layer and avoid excess leakage current leading to destruction.Sell them "as is", with estimated manufacturing year, buyer must understand electrolytic capacitors are not eternal.It's beyond me why anyone would like to buy them, though, shipping alone is costly. Electrolytic capacitors are not expensive when bought new.

author: madires
author_rank: Super Contributor
timestamp: January 24, 2022, 02:29:31 pm
content: Maybe someone restoring vintage stuff might be interested.

author: jonpaul
author_rank: Super Contributor
timestamp: January 24, 2022, 02:55:32 pm
content: We have boxes of parts from 1950s...60s and the lytics still are fine if well sealed and high quality.The Philips and other EU made parts have very long shelf life.We test and reform caps on old valve equip if the epoch is 1930s...1950s.Test for leakage at the rated V.Jon

author: rsjsouza
author_rank: Super Contributor
timestamp: January 24, 2022, 02:58:11 pm
content: You need to test leakage at or near the operating voltage. A capacitor that reads fine on, say, 2~3V of a simple tester might not have enough dielectric to sustain larger voltages.One detail: the 12kV Cornell Dubillier is probably not electrolytic, but a full evaluation of its condition is probably required before using it at nominal voltages.

author: Gyro
author_rank: Super Contributor
timestamp: January 24, 2022, 05:55:58 pm
content: Quote from: rsjsouza on January 24, 2022, 02:58:11 pmNo, that looks like a film capacitor - such high voltage capacitors are pretty hard to find, they're expensive so don't bin it!

author: Kleinstein
author_rank: Super Contributor
timestamp: January 25, 2022, 08:18:11 am
content: The old electrolytic ones are of little value: many can be bad and even if still OK they are quite bulky and not very reliably any more. So one would hardly use them, excepts maybe for a restauration. One may still use them for a short test circuit or the small ones on the bread board.The non electrolytic caps are usually still good.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 25, 2022, 10:39:24 am
content: Certainly wouldn't bother with the piddly electrolytics, but the big ones may be usable.Hrm, ironically I have little use for larger electrolytics myself, so I don't even use the few I have collected over the years...Mind that they probably need to be reformed (charging with limited current (a few mA?) to rated voltage), but other than that, can still be useful, yup.If there's any tantalums in there (almost thought some were pictured, but I guess the "PTCs" on that baggie suggest otherwise!), they should be fine at any age. Can be tested in a similar way; tants self-heal in a way analogous to reforming.What's the glass things in that one, tubes? Encapsulated capacitors? Also see ceramic tubular capacitors in there, those can be nice. Should be C0G I think? Or if not, then some variety of stable tempco (i.e., usually used for compensating inductor tempcos). Should be labeled much as resistors are, but in pF rather than ohms (multiplier = 1x pF's). Still usable today, nice parts, just, bulkier than MLCCs so can be hard to use outside of breadboarding, heh.Tim

author: Gyro
author_rank: Super Contributor
timestamp: January 25, 2022, 04:57:46 pm
content: QuoteThey look like vacuum thermistors to me, maybe the STC B14 (or at least Bxx) indirectly heated type. I suspect that the other parts in that bag are old STC rod type thermistors too.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 25, 2022, 06:13:59 pm
content: Oh weird, sounds like bolometer stuff (if so)? Pretty special purpose, but I wonder if the ham or metrology folks would use 'em...Tim

author: Gyro
author_rank: Super Contributor
timestamp: January 25, 2022, 06:32:21 pm
content: Good question. STC listed applications as Power measurement, AGC/voltage regulation, remote controlled resistors etc.I have a couple of 10k B14s that I was thinking of using for a thermal RMS converter (a lot bigger thermal response that heater/thermocouple and heater/diode) but haven't got around to it yet. They'd probably work well as RF power sensors too. Theoretically you could use them in place of the old R53 self-heating vacuum thermistor for Wein bridge oscillators, but the bead is a lot bigger and there is more thermal coupling to the outside world through the multiple lead connections.P.S. I see that you can still pick them up on ebay occasionally, eg:https://www.ebay.co.uk/itm/124302590120

author: eti
author_rank: Super Contributor
timestamp: January 28, 2022, 08:03:13 am
content: Quote from: wwjd1924 on January 24, 2022, 01:32:44 pmAsk yourself if you want to be the new "ElectroBoom"...