A Weston standard cell – an introduction to voltnuttery?

Weston standard cells are pretty, but can they be more than a broken antique? And yes, that is liquid mercury visible at the bottom of the left leg.

One Cell

One Cell

I remember using Weston cells at school during physics lessons to measure voltages more accurately that could be done with a standard analogue meter (DMMs being years in the future). The measurements are based on using a 1m ruler plus resistance wire plus an uncalibrated NiFe cell as a bridge, and use a Weston cell to calibrate the bridge. That technique (which is a good example of using simple materials, understanding and imagination – rather than merely throwing money at the problem) is outlined below.

Anyway, I have vaguely wanted a Weston cell ever since, a little more so since I got hold of an HP3468 and have wanted to check whether it is still “accurate”. I’ve wondered about buying one on ebay, but they are unjustifiably expensive and sufficiently fragile that I doubt they would survive shipping.

Unfortunately I’ve now found a cheap one, and I fear it might lead me down the expensive path of voltnuttery. Memo to self: do not become a voltnut.
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