Budget Precision Reference Capacitor - Page 1
Forum section: electronics / general

author: Terabyte2007
author_rank: Frequent Contributor
timestamp: October 10, 2014, 07:19:43 pm
content: I picked up an NOS Silver Mica precision 173200 nF (0.1732uF) .3% capacitor to use as my budget reference capacitance source. Reference checked against an Agilent Capacitance Meter at 173.12 nF, it's well within tolerance!Gotta love the old Russian military NOS.

author: SeanB
author_rank: Super Contributor
timestamp: October 10, 2014, 08:19:52 pm
content: I picked up a pair of 1uF precision caps as well at the scrap yard. 1uF 0.1% 200VAC at 20C, and as far as I can check they are still within specs, even with the trimming method used inside of adding polystyrene caps in parallel to up them to the correct value.

author: Terabyte2007
author_rank: Frequent Contributor
timestamp: October 11, 2014, 12:15:51 pm
content: Quote from: SeanB on October 10, 2014, 08:19:52 pmI would like to get a couple .1% but could not find any. Nice score!There is always this!http://www.ebay.com/itm/IET-General-Radio-1408-Air-Bath-Reference-Standard-Capacitor-/270881619941?pt=LH_DefaultDomain_0&hash=item3f11cd7fe5

author: SeanB
author_rank: Super Contributor
timestamp: October 11, 2014, 12:27:16 pm
content: Yes, but I could buy a house for what one costs though.

author: Terabyte2007
author_rank: Frequent Contributor
timestamp: October 11, 2014, 12:54:58 pm
content: Quote from: SeanB on October 11, 2014, 12:27:16 pmYou are correct sir! Nothing I would ever consider.

author: SeanB
author_rank: Super Contributor
timestamp: October 11, 2014, 01:06:16 pm
content: I could post you the half kilo block if you want, when SAPO decides to get off thier asses and back to work. At present the only way to send to the USA is via courier, and that is $150 per kilo, or for the first 3 pounds. That is kind of expensive.

author: Terabyte2007
author_rank: Frequent Contributor
timestamp: October 11, 2014, 01:19:27 pm
content: Quote from: SeanB on October 11, 2014, 01:06:16 pmOuch! I still may be interested, I'll let you know. Thanks!

author: bingo600
author_rank: Super Contributor
timestamp: October 11, 2014, 10:05:54 pm
content: I was lucky to get my hands on a HP 4440B for $88 incl shipping locally in DKDecade w. 0.25% precision.https://www.eevblog.com/forum/projects/reference-for-lcr-or-esr-meters/msg365032/#msg365032https://www.eevblog.com/forum/testgear/iet-de-5000-lcr-meter-in-uk/msg197797/#msg197797That was a nice score.What does the "russian" cost ?/Bingo

author: David Hess
author_rank: Super Contributor
timestamp: October 12, 2014, 11:41:11 pm
content: The best reference capacitor I have access to is inside of an ESI 250DA impedance bridge. The specifications in the parts list say that it is 0.099880 microfarads +/- 0.1% and trimmed to 0.1 microfarads externally. I do not have any way to verify its calibration but as far as I have been able to determine, it has not drifted since it was manufactured on June 28th of 1965 as shown in the photograph.

author: SeanB
author_rank: Super Contributor
timestamp: October 13, 2014, 08:00:23 pm
content: This is the one I got from the scrappie...http://mjlorton.com/forum/index.php?action=dlattach;topic=713.0;attach=2894;image

author: David Hess
author_rank: Super Contributor
timestamp: October 13, 2014, 09:00:58 pm
content: Quote from: SeanB on October 13, 2014, 08:00:23 pmRegistration is required to view.

author: Terabyte2007
author_rank: Frequent Contributor
timestamp: October 13, 2014, 09:52:32 pm
content: Quote from: SeanB on October 13, 2014, 08:00:23 pmDid you get it with the case and all?

author: SeanB
author_rank: Super Contributor
timestamp: October 14, 2014, 07:13:10 pm
content: I did, just lifted the skirt to have a peek inside. Measured it and it is likely still within limits, or at least agrees with the capacitance meter.