For the old-timers

My mother recently found this in the back of a closet. It was the poster for my seventh-grade science fair project from 1982 ... the hardware itself is long-gone; I distinctly remember cutting up the rats-nest of yellow wires to recover the parts. Check out my 5V regulator!

Discussions

Yann Guidon / YGDES wrote 05/17/2016 at 01:59

hmmmm .... it *could* work.

Despite the LED resistors at the wrong place.

Fortunately, DDL solved all these issues.

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Ted Yapo wrote 05/17/2016 at 02:13

I learned that 7448 at a young age, and it screwed me up for years. It, too, uses negative logic - it shunts unlit segments to ground! I guess they did it because TTL is so much better at sinking than sourcing current. Or maybe it's open-collector outputs.

Yes, DDL is the answer - if it can't be done with a 3.3kHz clock, it's not worth doing.

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Yann Guidon / YGDES wrote 05/17/2016 at 02:22

Sorry, the slowest crystal I have found is 8KHz

http://www.ebay.com/itm/262177915220

I suppose you'll have to find tunnel diodes, PIN diodes and other ultrafast parts to drive this...

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tyapo@localhost>whoami

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