ELECTRO-CHEMICAL ELAPSED TIME INDICATORS

[Joe Gwinn]

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

[Don Y]

Post by Joe Gwinn
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.

[john larkin]

Post by Joe Gwinn
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.

[Joe Gwinn]

Post by john larkin

Post by Joe Gwinn
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

[Glen Walpert]

Post by john larkin

Post by Joe Gwinn
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.

[Jeff Liebermann]

Post by Joe Gwinn
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>

Post by Joe Gwinn
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

[john larkin]

Post by Jeff Liebermann

Post by Joe Gwinn
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.
<https://us.rs-online.com/mkt/lp/suppliers/te/te-top-products/pdf/te_agastat.pdf>
<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.
<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>

Post by Joe Gwinn
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.

[Don Y]

Post by Jeff Liebermann
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.

Post by Jeff Liebermann
<https://us.rs-online.com/mkt/lp/suppliers/te/te-top-products/pdf/te_agastat.pdf>
<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.
<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>

[Crash Gordon]

Post by Joe Gwinn
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.

[Joe Gwinn]

Post by Crash Gordon

Post by Joe Gwinn
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.

Post by Crash Gordon
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