Nixie Shot Timer Adds Useful Elegance To Espresso Machine

Once you’ve ground the beans and tamped the grounds just so, pulling the perfect shot of espresso comes down to timing. Ideally, the extraction should last 20-30 seconds, from the first dark drips to the tan and tiger-striped crema on top that gives the espresso a full aftertaste.

[Marco] has a beautiful espresso machine that was only missing one thing: an equally beautiful shot timer with a Nixie tube display. Instead of messing with the wiring, [Marco] took the non-invasive approach and is using a DIY coil to detect the magnetic field of the espresso machine’s pump and start a shot timer.

An LM358-based op-amp magnifies the current induced by the machine and feeds it to an Arduino Nano, which does FFT calculations. [Marco] found a high-voltage interface driver to switch 170 V to the Nixies instead of using two handfuls of transistors. Grab yourself a flat white and check it out after the break.

The last Nixies may have been mass-produced in the 1980s, but never fear — Dalibor Farny is out there keeping the dream alive and making new Nixies.

11 thoughts on “Nixie Shot Timer Adds Useful Elegance To Espresso Machine

  1. Those Nixie tubes are glorious.

    FFT didn’t even occur to me in this kind of setting.

    There’s got to be a simpler more reliable option? Running the FFT seems to be he biggest computational task here?

    Arduino go brrr…

    1. These E61 style machines are typically very sparse on electronic hardware. I think some of these don’t even have a microswitch to start the actual pump. Simply flipping the lever to start a shot will drop the pressure in the brew loop and kick the pump pressurestat on. Most newer machines have integrated controllers for pre-infusion and built in PID control (the one in the video looks like an aftermarket unit).

      I can also see not wanting to make changes to a $1500+ machine especially if you’ve still got a warranty on it.

    1. Dunno I found it disturbing too, seems to be unnecessary since he has a few videos of the tubes being controlled without the blanking. He also seems to have cycle through all the numbers at the start…

      Maybe it was a quirk of how he controlled the cathodes (using a 32bit shift register)…. Well maybe he blanks them because he was having a odd trail effect from the natural persistence of vision from nixies?

      Annoyingly no code that I can find.

  2. Probably for effect. Although it is recommended to occasionally trigger all elements of a Nixie tube (something about long-time unused ones otherwise getting covered in residue), that wouldn’t be necessary to do on every digit.

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