Anode voltage is easy; just use a resistive divider to get the voltage within the range of your ADC, and be sure to put a filter cap (0.01uF should work) at the ADC input (most ADC inputs appear as a switched-capacitor).
Current is a different animal. The easiest way to dodge this is to use a current-limit circuit at each anode and you really dont need to measure it anymore. Anode current can be measured at the cathode side by tying all of the cathode drivers together, then connecting to GND thru a sense-resistor. For example, if you use an HV5530 to drive your cathodes, connect all of the VSS pins together, then to GND thru a sense resistor. If you drive 3 tubes from single HV5530, your max current will be about 15mA. Next, select a sense-resistor that will give about 1V drop at 15mA; by ohms law this works to about 67 ohms. Be aware the sense-resistor will affect the signal-integrity into the HV5530, so be sure to use the recommended input levels (12V logic), and this will directly impact your low-level noise margin. But with a 1V drop, the overall impact to noise margin at 12V signal swing is negligible. The other option is high-side current-monitoring. You could use a cheap analog or digital meter and put in-series with the anode supply. If you want to extract that info for you microcontroller, then your best option is to have an A/D converter on the high-side, and use opto-isolators on the serial interface to the ADC. There will be a fair amount of support circuitry for this, so be warned. -- 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/48ac0dba-e9f9-4a8a-a11c-1bab1f3a824d%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
