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A project log for Clockwork germanium

A retro version of Yet Another (Discrete) Clock, with vintage parts

SHAOSSHAOS 04/07/2016 at 06:461 Comment

Today I received some germanium diodes from ebay (1S34 that is the same as 1N34) and decided to replicate circuit from that Russian magazine again - germanium diodes on the left (inputs) and single silicon diode connects transistor base to the inputs common point. And it worked ;)

But voltage transmission curve was not perfect - threshold is too skewed:

Last time I shifted threshold by adding more diodes in transistor base circuit, but now I try something different - reversely connected Zener diode ;)

Initially I connected 3V Zener, but threshold goes not too far with it:

Then I tried 5.1V Zener:

Much better :)

With 4V power this circuit again reached 200 kHz:

Then I tried even more unusual thing - red LED :)

And it worked! U-curve looks like this now:

LED emits light in "zero" state (indicating AND function ; )

So we got NAND germanium gate with indicator showing AND function :)

Discussions

Yann Guidon / YGDES wrote 04/07/2016 at 06:54 point

Awesome !!

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