[time-nuts] low power divide by 5

[Peter McCollum]

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


On Thu, Jul 2, 2020 at 2:29 PM Gary Woods <garygarlic at earthlink.net> wrote:

> On Thu, 2 Jul 2020 19:23:03 +0200, you wrote:
>
> >Makes me think one could use the input signal edge to synchronize a
> 2N6027 based programmable unijunction oscillator, thus effecting a divide
> by 5. Unlikely the 6027 would be fast enough for 50 MHz, but maybe a 2
> transistor equivalent using RF transistors? Output would be nowhere near
> the 40%-60% range, though. Might just have to build one for fun.
>
> And _that_ makes me think of an early Navy airborne Loran set that
> used step counters to make the time base.  Adjustments were through
> holes in the side of the case, because some poor soul would have to
> tweak them now and again.
> --
> Gary Woods O- K2AHC   Public keys at home.earthlink.net/~garygarlic, or
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