Yes I have relevant experience with Lifters, fingerprints generally are a nightmare.
May also be worth mentioning that different grades of IPA are more or less useful, it absorbs water in its pure form so this needs to be taken into account. Use "no clean" fluxed solder if possible as it works well. Also relevant, don't forget that NASA like using splice joints where the wire is tied into essentially a reef knot. This is for all sorts of reasons not least visual inspection of the joint at regular intervals and anti- vibration measures are used like clear heatshrink. ________________________________________ From: volt-nuts <volt-nuts-boun...@febo.com> on behalf of Poul-Henning Kamp <p...@phk.freebsd.dk> Sent: 17 February 2018 09:10 To: Discussion of precise voltage measurement; Randy Evans Subject: Re: [volt-nuts] Low noise reference -------- In message <CANwu9JY-_o80YoeN_-hnXFxsYuQ=vkon0yw_roovegjhh3h...@mail.gmail.com> , Randy Evans writes: >I was concerned about the leakage through R1-C1. Ideally there should not be any voltage across C1 because C2 "bootstraps" it, so C1's leakage resistance should not matter at all. >In all cases the leakage, as measured with a >Keithley 414 picoammmeter, showed a leakage or around 0.08 uA at 10V That kind of currents take you into the territory where there are no insulators, only conductors which are not very good at it, such as expoxy, air, humidity, fingerprints etc. The very first thing you want to do, is wash your entire construction in isopropanol[1]. The next thing you want to do is make sure you are not fighting a an electrostatic phenomena: Only measure inside a grounded metal enclosure. Cookie tins work great. Finally make sure you are not measuring Seebeck/thermo-electric phenomena: Measure while you raise and lower the temperature of the hole thing and look for gradients. >I also tried a 0.68 uF polystyrene capacitor and also saw leakage current >variations, although much less than the electrolytic and tantalum >capacitors, as one would expect. I actually have in mind to buy a couple of the cheapest "teflon" capactors from the audiohomøopathy world, and see if that is really what it claims to be. Poul-Henning [1] I've been told that the liquid used in dishwashers to avoid spots on glass, a mixture of soaps and alcohols, is also good for electronics, but I have not tried it. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there. _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.