13 Jul
2007
13 Jul
'07
8:53 p.m.
From: Brent Hilpert <hilpert at cs.ubc.ca>
dwight elvey wrote:
Hi Bret
I recall that is was an HP counter. I don't recall the fastest count but
it was on the order of either 10KHz or 100KHz. I don't think it was
less then that but it may have been 1MHz. I recall that like many of the
HP counters of the time, the other decades were the inline 10 ea bulbs. I
don't recall if these were neon or incandescent but I think they were
neons driven by dual triodes. I do believe that the ring counter did
have a purplish glow.
Dwight
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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).