[time-nuts] cheap USB voltage sensor

Poul-Henning Kamp phk at phk.freebsd.dk
Fri Jan 13 15:19:40 EST 2012


In message <20120113200200.14805.qmail at s421.sureserver.com>, "=?iso-8859-1?Q?be
ale?=" writes:

>I have some and they work well. Here's a plot of voltage vs time
>on an AA battery, showing the 18 bit performance (1 LSB = 15 uV).
>Noise is generally +/-1 LSB.
>https://picasaweb.google.com/lh/photo/q7Lq4oAX_0347S8BO0eHSA

Did you try to hold the battery in your hand while you did that ?  :-)

Be aware that once you get to approx microvolt, you have to take
into account things like the temperature difference between plug and
socket because the thermoelectric effect kicks in.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at 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.




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