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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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2nd Jul 2020, 7:52 pm | #1 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 14,007
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"Staircase counter" ?
Historically, divide-by-powers-of-two circuits have been easy - you just chained a series of flip-flops.
But for odd-powers-of-two things were harder. I recall a circuit designed to do both odd-and-even division: basically it used a half-wave-diode-voltage-doubler fed by a really-narrow capacitor integrator - so it only 'saw' the leading-edge 0-to-1 transition - and then fed the integrated pulses into a capacitor, whose charge ramped-up with each pulse, in staircase-fashion. Then there was a Unijunction-transistor that 'looked' at the charge on the capacitor and when it considered it was at the top of the staircase, triggered - so providing the required output-pulse and also dumping the charge on the 'staircase' back to the bottom. These worked OK for divide-by-3 or 5, but component-drift made them unreliable for divide-by-7 or divide-by-9. Thankfully, in the 1970s we got the TTL 7490/7493 chips which did it all digitally and much-more-reliably. But I'm wondering - was there an official name for the "staircase" divider ?? Last edited by G6Tanuki; 2nd Jul 2020 at 8:15 pm. |
2nd Jul 2020, 8:17 pm | #2 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,899
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Re: "Staircase counter" ?
Charge-pump divider, sometimes
David
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