7400 competition entry: Constant load with nixie readouts

Want to test your power supplies? How about using a constant load with a Nixie display, built entirely out of 4000 series CMOS logic chips.

This is a Constant Load generator that is controlled by a keypad. When I started this project I was not sure what it would end up being so I built in in modules that are interconnected. This gives me greater flexibility and it is easier for a beginner to understand the schematics and operation of the parts.

I use only CMOS 4xxx -logic running on 12 volts with the exception of the Russian K155N1 Nixie drivers – they are TTL and uses 5 volts.

Check out the video after the break.

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