Re: ELECTRO-CHEMICAL ELAPSED TIME INDICATORS

On Sat, 14 Dec 2024 21:56:56 -0800, Jeff Liebermann <jeffl@cruzio.com>
wrote:

On Sat, 14 Dec 2024 14:29:38 -0500, Joe Gwinn <joegwinn@comcast.net>
wrote:
>

There was a question (from Larkin?) on non-electronic time delay
components, and I recalled such a thing from the 1970s, when I
considered using it to sequence an electromechanical gadget.  Turned
out to bet too complicated in that application, and went to a CMOS
counter.

>
Sounds more like a timer than an elapsed time indicator.  In the
1970's, we used Agastat pneumatic timers to generate fairly long time
delays up to about 30 mins.  The original technology was a piston and
cylinder, with a controlled air leak.
>
Electro-Pneumatic timing relay:
<https://us.rs-online.com/mkt/lp/suppliers/te/te-top-products/pdf/te_agastat.pdf>
>
There are other companies that make the same type of timer:
<https://www.google.com/search?q=pneumatic+timer>
<https://www.google.com/search?q=pneumatic+timer&udm=2>
I suspect that someone had contrived a MEMS pneumatic timer, but I
couldn't find one.
>
Agastat is now owned by TE Connectivity:
<https://www.te.com/en/plp/agastat/Zn5p.html?n=42691&type=products&inStoreWithoutPL=false&q2=>
<https://www.te.com/en/products/brands/agastat.html?tab=pgp-story>
>

Anyway, the name came to me today, and it is still made.
>
Curtis coulometers are analog Elapsed Time Indicators (ETIs) which use
an electro-chemical plating process to integrate current over time.
>
.<www.curtisinstruments.com>
>
.<https://lampes-et-tubes.info/uv/Curtis_coulometers.pdf>
>
This uses mercury, but if I recall correctly, the 1970s original used
silver.  I think it was called a coulcell.  The original company seems
to be gone.
>
Joe Gwinn

It's a form of mercury coulometer. That has a wikipedia page.