On 12/14/2024 12:29 PM, Joe Gwinn wrote:

Curtis coulometers are analog Elapsed Time Indicators (ETIs) which use
an electro-chemical plating process to integrate current over time.

Yes, the ones that I have look like a tiny (very small OD, very short length) old-fashioned (Hg) thermometer.

I was originally going to install them in some cassette decks (to track
run time) but couldn't decide if I wanted to track power-on-hours,
playback hours, etc.

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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.

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

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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.

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

The first residential electric meters, in the Edison DC days, were electrochemical. I think they weighed something to set the bill.

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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

--
Jeff Liebermann jeffl@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

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On 12/14/2024 10:56 PM, Jeff Liebermann wrote:

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.

"Elastic Stop Nut" is all I remember from them. I scrounged parts from
the controls for a set of pin-setters (from a defunct bowling alley)
as a kid. In addition to the interlocking "Set-Reset" relay latches
(great for storing a bit!), these were the most interesting as
they would let me delay an action (as long as I kept the coil energized
cuz releasing the coil reset the mechanism).

There was a small screw at the top that you used to adjust the delay.

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>

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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.

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On Sat, 14 Dec 2024 14:57:00 -0800, john larkin <JL@gct.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.

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

The first residential electric meters, in the Edison DC days, were >electrochemical. I think they weighed something to set the bill.

I do recall reading of that. Weighing was used, as I recall as well.

Joe

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On Sat, 14 Dec 2024 14:57:00 -0800, john larkin 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.

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

The first residential electric meters, in the Edison DC days, were electrochemical. I think they weighed something to set the bill.

https://www.watthourmeters.com/history-of-meter-companies

1882 - Edison's first electric company

Edison starts up his first electric company for incandescent
illumination.
Initially he started out with a per-lamp rate. This was unsatisfactory so
he developed a chemical ampere-hour meter that consisted of a jar holding
two zinc plates connected across a shunt in the customer's circuit. Each
month the electrodes were weighed and the customer's bill determined from
the change in their weight. This meter was inefficient and error-prone.
Edison did also develop a motor-type meter but preferred the chemical
meter because of his interest in chemistry.

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On 12/14/2024 1:29 PM, Joe Gwinn wrote:

Curtis coulometers are analog Elapsed Time Indicators (ETIs) which use
an electro-chemical plating process to integrate current over time.

I have a box of these squirreled away in a box someplace.
(Unfortunately I have a *lot* of boxes)

There was a paper card underneath the tube that you would slide to
"zero" the meter. And when it hit the end of the scale, the tube could
be removed (like little fuse clips) and flipped over to count more.
ISTR that if you allowed the electrolyte "bubble" to get all the way to
either end of the tube the device was ruined.

The accuracy of the device was proportional to the accuracy of the
current you passed through it.

--
I'm part of the vast libertarian conspiracy to take over the world and
leave everyone alone.

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On Mon, 16 Dec 2024 17:34:12 -0600, Crash Gordon <uucp@crashelex.com>
wrote:

On 12/14/2024 1:29 PM, Joe Gwinn wrote:

Curtis coulometers are analog Elapsed Time Indicators (ETIs) which use
an electro-chemical plating process to integrate current over time.

I have a box of these squirreled away in a box someplace.
(Unfortunately I have a *lot* of boxes)

There was a paper card underneath the tube that you would slide to
"zero" the meter. And when it hit the end of the scale, the tube could
be removed (like little fuse clips) and flipped over to count more.
ISTR that if you allowed the electrolyte "bubble" to get all the way to >either end of the tube the device was ruined.

I sorta recall that detail.

I did a design with such device in the late 1970s, and when the
design was done, I turned to my business partner and said that there
was no way this would work in the real world because it was far too
hard to come up with any plausible design. I started over, and
designed the CMOS replacement in a day or two. And it worked just
file in the field.

The accuracy of the device was proportional to the accuracy of the
current you passed through it.

Yes, but not a big problem in my application..

Joe Gwinn

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