[time-nuts] Interesting Patent

David Forbes dforbes at dakotacom.net
Tue May 16 14:32:45 EDT 2006

Brooke Clarke wrote:

> Hi:
> I came across a 1946 patent for a vacuum tube based counter circuit that 
> will divide 60 Hz down to 1 Hz.  It's interesting in that there's a 
> discussion about the advantage of using binary instead of base 10 and 
> also about using feedback to change the scale of the counter from 64 to 
> 60 (or 50).  See:


This appears to predate the old Berkeley and HP decade counter modules 
by quite some years, although it is slightly different in that it 
treats a single base-60 digit instead of two BCD digits.

Amusingly, by the time of color television in the fifties, RCA was 
selling a low-cost color bar generator whose sync generator used the 
phantastron divider instead of this binary divider. The phantastron 
was also used in the HP counters for the reference clock divider; it 
is a two-tube divide-by-N circuit that charges a capacitor with N 
little pulses, then triggers and resets itself.

Also amusing is the patent application date of 1942 and the granting 
date of 1946 - these times bracket ENIAC's protracted development and 
building period. However, ENIAC did not use binary counters - it used 
decimal up/down ring counters which were a faithful emulation of the 
mechanical wheel accumulators used in adding machines of the day.

All in all, a nice bit of history.

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