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I previously worked on Virtual Reality and other hardware at Valve.  I currently work at Google[x].

Prior to starting at Valve, I built computer peripherals such as keyboards, mice, and joysticks that were designed to be used inside MRI machines.  My company, Mag Design and Engineering, sold these devices directly to researchers at academic institutions who used them to publish scientific papers in peer-reviewed journals.

After work, I spend time on many different types of projects that usually involve circuit design, machining, material selection, and general fabrication/hacking.  My favorite place to be is my home workshop.

ben dot krasnow at gmail




Friday, May 2, 2014

Unusual usage (hours) counter with mercury capillary

This is a usage counter that works by moving mercury in a capillary tube via electrochemistry.  As electricity flows through the device, mercury atoms are transferred across an electrolyte gap in the capillary. The position of the gap changes as mercury is transferred, and shows how much total charge has been passed through the device.

I realize that the divider network looks more like 20:1.  This might kill my theory that the mercury ions are in the 2+ state.  I'm really not sure.


  1. cool - yes: I found it interesting ! Thanks!

  2. So did I - really interesting. These devices are found on old Russian electronic test equipments. Since the counter can't be reset this gives also an idea about the lifetime of such an equipment. I have seen these counters on oscilloscopes and frequency dividers devices.

  3. What is the name of the physical affect in this setup? It's not electrophoresis, right?

  4. excellent analysis..i loved the math involved

  5. I have one of those on a Russian sampling scope.
    This is an early implementation of a memristor, many years older than HP's version (a conical tube would lead to a strong change in resistance, but that is just a detail).

    Btw. your audience is waiting, when are you going to make artificial diamonds?