On 7/2/20 2:13 PM, Peter McCollum wrote:
Another way to achieve divide-by-N is with a non-retriggerable one-shot,
adjusted to the appropriate time value.
Back in the 40's/50's, the common tube circuit was called a Phantastron
(really, look it up!).
Phantastron dividers were used in several of the early HP counters (i.e.
HP524B), because you could achieve (for example) a decade divider with a
single tube, whereas a 'binary' solution requires 4 tubes (like in the HP
AC-4A decades).
If a 50% duty cycle is needed, then do a divide by N/2 with a Phantastron,
then a single flip-flop gives you 'N' with a 50% duty.
Note that the Phantastron type divider only works if the input freq is
known and fixed, because the one-shot delay has to be adjusted to a
specific value.
Pete
And you can be clever if you can trigger on both rising and falling
edges, so you get basically a x2 and a divide by 5 in the same circuit,
followed by the divide by 2 to make the duty cycle 50/50.
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