Name of analog/discrete coulomb integrator?

[matseng]

I remember reading about an analog coulomb integrating device way back in the 70's or early 80's.   As far as I remember it looked something like an axial varistor.

It was a purely analog device that moved ions inside it as the (varying) current flowed thru it, and was then "read out" by applying a reversed current of known value while measuring how long it takes to completely move the ions back to the original side.

Not sure if it was ions, or atoms, or molecules, but it was something that actually moved from one side to the other at least.

Anyone knows what this device is called, and where I can get a few to play around with?


(Edit: I know that this is a gas discharge device, it's just an illustration of how I remember my mystery device looks like)

[max666]

I have no idea what you are talking about, but what you are describing sounds to me suspiciously like one of these exotic devices



The picture you posted is a EPCOS gas discharge tube, which below the breakdown voltage will behave more or less like a capacitor (probably not bad for a current integrator, I imagine they have very low leakage)

[matseng]

Nope, it was not a cap.    It doesn't store a charge like a cap or battery.  But just like a battery it is some kind of electrochemical device where something is physically moved from the anode to the cathode (or vice versa), but without causing a residual voltage after the charging.  So like a energyless battery...

This was like 30-40 years ago, so it might just be something that I either imagined, or just did misunderstood at that point in time.

And the picture I attached was just an illustration of how I remember the device looked like - an axial varistor/mov like thingie.

[CatalinaWOW]

I don't know if it is what you are talking about, but in that time frame there were run time meters that worked on that principal.  A constant voltage was applied, and thus the amount of plating was proportional with time.  As I recall the plating was silver, and at least some of them had a window that allowed visually reading the results.  They were axial lead devices, though the ones I saw advertised had a longer length to diameter ratio than the one you pictured.

[Alex Eisenhut]

That picture is a gas GDT.

http://media.digikey.com/photos/Epcos%20Photos/EC%20SERIES.jpg

No idea what you're talking about, but it sounds chemical.

[T3sl4co1l]

An electrochemical cell with a reversible reaction will do that: the terminal voltage stays relatively low (the reduction potential of the reaction, plus resistive loss, plus "spooky" effects like overpotential and ionic diffusion), and can be arranged to be read out optically, mechanically or electrically.

Example: http://4hv.org/e107_plugins/forum/forum_viewtopic.php?77016.post

Tim

[matseng]

Tim, now we're getting somewhere!   Didn't know about the possibility of optical readout, that's interesting.   I'll read the thread at 4HV and see if I get any wiser.  Thanks.

[codeboy2k]

modern equivalent cool-o-meter

[max666]

Now that I know what you're talking about, I remember I have actually seen an application of this:

I highly recommend Applied Science's channel. Watching his videos makes me feel like a drooling idiot 

And thumbs up for the cool-o-meter as well, I think it's wizard 

[dexters_lab]

i remember having a few of these back when i was a kid, they were just in unmarked boxes and had no idea what they were at the time... no idea where they went 

the ones i saw had a scale built into the glass envelope, like an old glass thermometer

[niflheimer]

Closest I get to that is a mercury power meter - it will move the mercury from one end to the other based on the total energy passing through it.

[SeanB]

I have some Panasonic video duplicators that have those in them. I should really tear one apart and send you one Marc. Will go nicely with your Umatic coffee coaster.