If You concider blanking the tubes, that includes PWM for intensity control, by the cathode drivers then use something that can take the whole anode voltage. I.e. MPSA42. Period.
<http://www.google.com/url?q=http%3A%2F%2Fwww.mcamafia.de%2Fnixie%2Fimages%2Fnix_th01.jpg&sa=D&sntz=1&usg=AFQjCNHS_0Tt0YrsgRmQN9ev78JuwS6WOQ> If not You can clamp the voltage to a lower level and use lower rated transistors. The clamp must be there, transistors degrade from breakdown even if they don't may fail immediately when the current is limited. The needed clamp voltage minimum level can sometimes be found in the tubes datasheet. Look for "selection voltage". The antique 74141/7441/K155ID1 are such devices. The western parts have a 60-something clamping voltage, the soviet versions about 100V. Those are good for any tubes. Unfortunately they are power hungry at about 25mA, otherwise they are a good choise. The K155ID1 use to be readily available at eBay. Some tubes have very low selection voltages. I have some recollection of ZM1000 to be such a device. I also remember having seen some clock built with 40?? CMOS at 15V driving nixies directly. The protection diodes to Vdd was used for clamping. That's a bad pracice that could possibly damage the devices even if Vdd is safely held down by some means to ensure it won't rise. -- 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 neonixie-l+unsubscr...@googlegroups.com. To post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/dcc427cf-d8ff-4e3e-82e8-c23554611a43%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
