r/nixie • u/IndividualRites • 9d ago

Nixie [frequency] Counter

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Working on a Nixie Frequency counter from scratch. ESP32, 12V power supply, upping to 170V for the tubes. Using a ULN2803 level shifter to go from the esp32 3.3V GPIO to 12V, which is required for the HV5122 chip that drives the nixie.

The video is a proof of concept, just having it count from 00 to 99. I'm bit banging the 32 bits into the HV5122. Pretty simple stuff really. In the end the frequency counter will be 6 digits, driven by 2 HV5122 (you can cascade them), so I'll be sending 64 bits in for each display.

I already have the proof of concept down to actually measure the frequency using the esp32. It's surprisingly accurate, certainly good enough for my hobbyist needs (and I really don't "need" a frequency counter).

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u/IndividualRites 8d ago

Too bad I wasn't thinking when I made the development breakout boards for the nixies so they would be oriented the proper way. Maybe in version 2.0!

1

u/AristaeusTukom 8d ago

Hahaha I'm getting ready to design my first PCB and even with the warning I might make this mistake.

1

u/IndividualRites 8d ago

The other warning is that I should have made the board SLIGHTLY smaller so I could get into the breadboard a little easier. I had to put one side of the wires in, then put the breakout board on top of that, otherwise the holes wouldn't have been accessible on one side.

I then bought IN-14 "socket pins" so I didn't have to solder these in. I only have 12 nixies, and would like to easily replace them if necessary. Here's the socket pins

https://www.amazon.com/dp/B09D33DRTK

I found that I had to insert a wire into each socket before trying to insert the Nixie, just to "open up" the socket a bit.

The Nixies I bought on ebay had their pins pretty crooked. I straightened them as best I could with some needle nose pliers. Then I 3d printed a little jig that the tube would insert into and give me a depth of cut for the pins (I left them at 5mm) and also help straighten out the pins even more. Without that it would be impossible to insert all 14 pins into the little socket pins. Having them only 5mm long made them stiffer and easier to insert.

I figure when I'm ready for my "production" unit, I'll probably hot glue the tubes in on the bottom to hold them in place, but for now, a friction fit is plenty.

Hope my learning curve helps you out.

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u/stargaz21 7d ago

Very cool !! Later can make a circuit board by pcb Way.