13 Jul
2007
13 Jul
'07
10:17 a.m.
dwight elvey wrote:
As a note on the dekatron, these were used in some of the early
HP counters. They were used as the first, or highest frequency,
state of the counters. They were quite fast!
Dwight
I beg to differ on this. I have a couple of dekatron counters and they
only seem to be good to some 10s of KHz (unless of course, you mean that that
was pretty fast for the time). Interestingly, one of these counters uses two
types of dekatrons, the only obvious difference between them being the colour
of the glow and the part number. The ones in the slower speed decades are the
usual neon glow, in the higher speed decade a purplish glow (xenon?). I presume
the purplish glow gas ionizes faster than neon.
I should try to ascertain more accurately the max rate of the purplish deks
but haven't yet as one of the two in the unit is failing.
I haven't seen dekatrons in HP counters, I believe their first counter was the
524A and, unless it was radically different than the 524B/C/D, didn't use
dekatrons. Certainly the rest of the 520 series was vacuum tube flip-flops
(AC-4 modules).