Subject: Tube logic (was: HP nixie tube module)

From: J Forbes <[email-masked]>
Date: Sat May 24 12:22:42 2003

On Tue, May 20, 2003 at 04:24:22PM -0500, Bill Richman wrote:

> All I know is they were used in counters.  These have a binary to
> 1-of-10 decoder made out of photoresistors and neon bulbs (!) in
> the black box.  It's not a HV supply like he guessed.
> 
> It should be possible to make a clock but he'll have to modify some
> of them to reset before the usual cycle of 0-9.  Resetting at
> 23:59:59 is probably harder and would take some kind of external
> logic.
> 
> They already have a feedback to make them reset after 9 instead of
> counting to 15 - it just has to be modified.
> 
> On the other hand if he wants to make a clock, nixies are cheap
> and it might be better to just leave the counter modules as-is and
> use some logic more suited to counting the time (which is not
> 10-based).

I have a tube digital clock, which I made out of a Beckman Berkeley 
counter.   The counter uses decade modules, each with four tubes used as 
flip-flops, and ten neon lamps which display the count on a numbered 0-9 
plasic window.  The HP modules work pretty much the same way as the 
Beckman tube modules, although the binary to decimal decoding scheme is 
different in that it uses light and photoresistors instead of resistor 
networks.

http://www.mindspring.com/~jforbes2/tubeclock/index.html

shows my clock.

The counter modules could possibly be used as the basis for a tube 
computer...maybe.  I have a bunch of extra modules.  I believe my 
brother has the schematic for the HP counter that uses the nixie 
modules, and he has one of the HP counters.

-- 
Jim

Visit the Selectric Typewriter Museum!
http://www.mindspring.com/~jforbes2