Flip-flop in detail

A project log for Restoring the TRANSBINIAC computer

Bringing a vintage DIY binary counting computer back to life

johnJohn 09/07/2020 at 20:371 Comment

Here's a closeup on one flip-flop module (#1 in the machine's sequence, or top-left as seen in the main photos.) The construction obviously shows skill, although I'm guessing not a lot of formal training. Lots of odd wiring choices that I feel like could have been done in a more straightforward way. He was a fan of compound joints with many connections coming together.

In that pic I have a few joints desoldered for testing purposes. Another odd choice is that two of the other modules have their transistors installed upside down. Rather than just flip them over to make all the units identical, he wired those two modules in mirror fashion--confusing. I can't tell if they all were made at the same time or not. The parts aren't identical from unit to unit but whether that means they were done at different times or just used whatever was on hand I can't say.

All the original caps have drifted way off, but the resistors check out and the transistors seem OK, although with a little more leakage than you'd want in a modern piece. Some people have brought up keeping the original caps for aesthetic reasons and hiding the new ones. I don't really mind the new ones and I like the snazzy yellow, but what're your thoughts? I'll rebuild this soon and test it out.


Dr. Cockroach wrote 09/07/2020 at 21:16 point

I think that your choice of the yellow caps is fine and their look is in keeping with the old ones. As far as wiring style. That's the way I wire my projects now ;-)

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