What is your method of current regulation? For example, do you use a PnP transistor or the lm317 method, or something else? I have room to add something for my anodes, but I'm unsure if using a transistor would be accurate.
On Sunday, 14 August 2016 03:02:17 UTC-4, gregebert wrote: > > I use current-regulation on my nixie designs, and I've done cathode-side > as well as anode-side regulation. Where you decide to regulate the current > depends upon the driver you select. So far, all of my designs use > direct-drive (non-multiplexed). > > My 'Tomorrowland' clock uses HV5532 drivers (it has fourteen IN-18 tubes), > so I regulate current on each anode. Yes, there are 14 current > regulators.... My wristwatch uses NPN transistors to drive the cathodes, so > I regulate the current on each segment. > > Since 10mA fuses really aren't available, I size the resistor in the > current-regulator so that it will operate at about 1/2 it's rated power > during normal operation. For example, an 0805 SMT resistor is rated for 1/8 > Watt, so I try to design for around 50-60mW. If a gross failure in the > regulator occurs, the resistor should overheat and open. I have not tested > it, though. I have a fuse on the power supply, and use the smallest value > that will handle max operating current. > > If you really want to be paranoid, monitor all of your anode currents with > a multi-channel ADC. I've never done that, but it sounds like a fun project. > > For cathode current-regulation, you would use an NPN or NMOS transistor; > anode-side would use a PNP or PMOS. I found that high-voltage PMOS devices > aren't nearly as common as NMOS. > > If you use MOS devices, I'd recommend a zener-diode across gate-source and > also very-high resistors (10Meg +) across drain-source to protect from ESD > or unanticipated voltage spikes. It's probably overkill but SMT devices are > so cheap and small it's worth the cost to me. > -- 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/d21d293f-f00e-4302-a67b-33cc03b415b3%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
