A lower voltage on the base would work, or an extra diode in series with the EMITTER to raise the turnon voltage by another 0.6V, or just pullup resistors on the chip outputs to make sure they go to a righteous 5V. Remember you still need those emitter resistors, otherwise the B-E diode will short the driver output to Vcc and cook it. It may be worthwhile to use those resistors to set the cathode current, since they have to be there anyway, and not use an anode resistor. I don't know, I've not tried it myself, so you're a pioneer. Be sure and tell us how it works out.
On Thursday, March 12, 2015 at 10:18:22 AM UTC-7, Dekatron42 wrote: > > Thank you for your answer! > > I'll try that as that makes it possible to use either the 74HCT42 or a > pair of 74HCT138s instead of a 74141 with just a few extra transistors and > resistors, unless you don't want to use anything more modern like any of > the Supertex HV-VFD drivers. Thanks for pointing out the difference between > TTL and CMOS in this case. > > Would an extra diode in series with the base or lets say a lower voltage > on the base work with TTL? If so a simple voltage divider or a zener and > resistor to the base would be a simple solution. > > /Martin > > On Thursday, 12 March 2015 17:58:55 UTC+1, petehand wrote: >> >> Yes, it should work perfectly in that application with a CMOS gate. I >> would not try it with a TTL gate though, as it relies on the output going >> to the 5V rail to turn the transistor off and bipolar can't get up there. >> To use TTL you would need to add pullup resistors to 5V on the gate outputs. >> >> On Wednesday, March 11, 2015 at 1:34:54 AM UTC-7, Dekatron42 wrote: >>> >>> Pete, will the cascode circuit work properly as a cathode driver if you >>> use for instance a 74HCT42 or a 74HCT138 to drive the transistor (they both >>> have inverted outputs going low when selected), using the collector of the >>> transistor to drive the cathode of a Nixie? >>> >>> /Martin >>> >> -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/1af15cab-334c-45d8-b18f-1fc189e30454%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
