> > > 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. >
Actually, the ESD clamp-diodes on the 4000X CMOS part would likely turn-on *all* of the cathodes, because they clamp to the VCC of the CMOS device. You would be surprised how durable ESD structures are. About 10 years ago I did the ESD design for an ethernet PHY and all of the I/O's had to handle zaps around 1 amp, some even more. A few mA for a nixie tube wouldn't do any harm to the IC; definitely a bad design practice, though, as you mentioned. ------------------------------------------------------------ My first clock was built with discrete 4000 series CMOS, but I used 450V/10Amp NMOS devices (yep, overkill but I got tons of them almost for free..) to drive the cathodes. I also run it directly off the AC mains (no transformer). The 3 I have now have been running flawlessly for several years now. -- 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/7e004ef7-87b3-419b-86a0-e799b10a4123%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
