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It was too easy...

A project log for Yet Another (Discrete) Clock

I HAD to finally do this basic "exercice de style" in digital electronics, using some hundreds of transistors and diodes...

yann-guidon-ygdesYann Guidon / YGDES 05/13/2016 at 00:110 Comments

I wanted to make a decade counter (like a 4017, which is the basis of this whole clock) and I soldered 5 more modules.

Then I tested them.

None of them worked.

The only difference with the first two was : the BS250, coming from a different source (from the far east, yes again...)

After a little test, it appeared that these are indeed P-MOSFET but with reversed pinout !

I had to desolder those 4×5=20 transistors and all the modules work now.


While wiring the 5-bits counter, it appeared that I did another mistake. There is no way to asynchronously reset the flip-flop to a given state. You have to solder a wire to the board. Somehow, I didn't bring the gates to the 7-pins connector !

I'll have to change that for the Rev.2 board...


Anyway I got something working tonight.

Not the desired decade counter but a 5-bits binary counter. Eh that's still something. And after I correct the above mistakes, it runs like a charm.

I have to find a solution for the reset, so I can make a reliable Johnson counter...

I can sleep now :-)

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