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On Mon, May 14, 2007 at 01:07:41PM -0400, David VanHorn wrote:
> > I've seen these things on quite a bit of older equipment, "Time
> > totalizers" consisting of a glass tube filled with a murcury bubble that
> > moves maybe an inch over 5000 hours. For instance the one at the bottom
> > of this page:
> >
> > http://www.surplussales.com/Meters/MtrTime.html
> >
> > I'm curious, do they still make them? How do they work anyway?
> >
> 
> I'd be surprised if anyone makes them anymore, ROHS compliance would
> be an issue.

Probably very true.

> They work by electroplating the mercury across the bubble. You feed
> them a small constant current.

Ahh, so basically the current transports the murcury ions from one
surface of the bubble to the other? Hence why you can put one in
reverse, and the bubble goes backwards?

So what's the bubble actually made out of?

- -- 
http://petertodd.ca
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