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A project log for Clockwork germanium

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

Yann Guidon / YGDESYann Guidon / YGDES 02/04/2017 at 22:4016 Comments

The last log (More bistables) found some explanations of the weird flip-flop schematic I initially found.

Today, a comment by RSMilward on hackaday.io brought a new light to the mystery !

This one comes from an even earlier publication (1961) in Popular Electronics, hosted on archive.org :


From the experience with the 10TFF and looking at vintage circuits, I realise something about edge-triggered flip-flops with only 2 transistors. In the 10TFF, a temporary value is held as a charge on one transistor's gate. This principle is found in the 2BJT circuits with actual capacitors, which are "protected" from the previous stage by a series resistors.

This resistor is critical for the speed and power consumption. The RC constant must be adapted to the system's speed. That's where the 2BJT circuits reach their limit... For the "slow" parts of the clock, this is not a problem and this will save quite a lot of germanium parts, but there are quite a few diodes and other passive parts.

Discussions

Dr. Cockroach wrote 02/05/2017 at 02:06 point

OMG - I grew up in Hialeah for my first 38 years and could take you to that address. I was 5 in 1961 :-) And PnP's make good Nands :-)

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esot.eric wrote 02/05/2017 at 01:15 point

That era... what on earth with having negative rails at the top?!

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Yann Guidon / YGDES wrote 02/05/2017 at 10:41 point

same reaction...

those diagrams need to be redrawn !

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jaromir.sukuba wrote 02/05/2017 at 11:06 point

No, all other diagrams need to be redrawn with negative rail on top!

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Yann Guidon / YGDES wrote 02/05/2017 at 11:20 point

muahahahaha

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Ted Yapo wrote 02/04/2017 at 22:57 point

Logic made with PNP power transistors!

Now, I've seen everything.

(I guess they're still smaller than tubes)

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Yann Guidon / YGDES wrote 02/04/2017 at 23:01 point

I have NO IDEA why they chose these. Maybe there was a cheap surplus/stock somewhere...

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K.C. Lee wrote 02/04/2017 at 23:16 point

Unlip them and you'll get logic circuit that can be activated by strong ambient light.  :P

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Ted Yapo wrote 02/04/2017 at 23:31 point

That solves the clock distribution problem - just get a strong strobe lamp.

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Yann Guidon / YGDES wrote 02/05/2017 at 10:49 point

@Ted Yapo now we're speaking :-P

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jaromir.sukuba wrote 02/05/2017 at 11:09 point

Well, the power transistors are here to switch incandescent lamps. Yet there is still some power margin left.

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Dr. Cockroach wrote 02/05/2017 at 13:22 point

I guess that being that there were no Leds you had to use regular lamps with higher current draw. I wish I could go back to those days :-)

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Yann Guidon / YGDES wrote 02/05/2017 at 18:37 point

Go back ? why ?

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Dr. Cockroach wrote 02/05/2017 at 23:21 point

I grew up with vacuum tubes so

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Dr. Cockroach wrote 02/05/2017 at 23:24 point

I grew up with vacuum tubes so still a bit old school :-) I am in my comfort zone with older stuff ;-)

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Yann Guidon / YGDES wrote 02/06/2017 at 21:34 point

I see you're trying new things with your cardboard project, neat ;-)

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