Two Tube Clock Board

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Roddy Scott

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Mar 7, 2019, 2:38:14 PM3/7/19

to neonixie-l

I have been working with Richard Scales, him the brains, me the brawn, in developing a two tube clock board that is in a modular form.

The board utilises a Wemos D1 mini which drives a 74HC575 into 74141s for each tube. On board power is from a 12v to 5v buck converter and HV comes from Yan's NCH8200 power supply the output of which switched by a pwm signal to opto isolators then to the 74141s for each tube.

Rev1.1.jpg

Richard bread boarded the circuit and I created the Rev 1.0 PCB. After this we made some modifications to accept a couple of different converters, added voltage test points and a manual WiFi reset button facility. This gave us Rev 1.1 from which I took the design to a circular format with matching tube boards to accept IN-18s and ZM1040s and the likes.

Rev 1.1a.jpg

Any B13B based tube can be used by just altering the anode resistors and tweaking the HV to suit the tubes.

The circular board format will give rise to some interesting clock designs with the tube spacing at approximately 40 mm and the board diameter being 90 mm.

Also included in plug in format is a BMP280 for barometric and temperature display, a neopixel denotes the various statuses and there are 3 input areas that can be used as under tube status indication or stand alone between the tubes indication.

Richard is currently refining the software from Rev 1.0 but the prototype built from this is still running away merrily with no issues.