As I have described the replacement. Its simple and will work. It eliminates the traditional transistor FF which I agree is much like the vacuum tubes. Further the decoding is not BCD its something stranger more like a grey code. But the counter is bcd on the board. But the 7490, 7475, and 7447 eliminate all of that. Been troubleshooting a 5248 M someone grabbed teh oscilator and A26 board from it. The a26 board was replced with 2 cmos chips and 1 transistor. Now I am at the counter gate. Darned if I don't have an issue in the dreaded tunnel diodes area. Such a lucky day for me. Need to cleanup and solder in the pseudo a26 board so I can more easily work on the gate. Regards
On Sat, Jan 9, 2010 at 6:37 PM, David Forbes <[email protected]> wrote: > At 9:00 PM +0000 1/9/10, <[email protected]> wrote: > >> >> I wondered about replacing nixie tubes and associated drivers with 7 >> segment LEDs in one of my (already hacked) units, to make it more reliable. >> I would use the BCD to drive the display, thus requiring a new interface >> board to be designed. I wonder if anyone else has considered such a radical >> remedy to the failing photocell problem? >> >> In case anyone is wondering 'WHY BOTHER?', my defence is that I too have >> an extensive collection of the plug ins, extending the usefulness of the >> basic instrument way beyond my budget for more modern equivalent >> instruments. >> >> Hope this question is not considered too far off topic for this forum. >> >> Peter Worrall >> > > Peter, > > The nixie tube is a wonderful thing. Surely you can't just find a couple > extra counters on ebay and scavenge them for parts? That's what I did. > > If you must redesign it, be aware that HP used 1950s pulsed counter methods > in that counter. It's utterly different from anything you will find in a > part with more than four legs. The circuitry has a lot more in common with > their vacuum tube counters. > > The most expedient method to replace the CdS photocell decoder would be to > use a PC board with a bunch of diodes as a logic decoder. Just make the > sense of the diode gates match that of the photocells, and copy the original > 'AND gate' logic of the hybrid. > > The storage method is non-obvious. It might require some extra chips if you > do it the new-fangled way. > > Nixies are still viable display elements, and they can be driven nicely > with the TD62084 or the similar TI SN75468. > -- > > --David Forbes, Tucson, AZ > http://www.cathodecorner.com/ > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
