There are lots of inexpensive isolated DC-DC converters. I've been using products from Cui and Recom. Here's a 12V unit I use: http://www.digikey.com/product-detail/en/VIBLSD1-S5-S12-SIP/102-1432-ND/989887
They are available in all sorts of input and output voltages. Be careful that some require a *minimum* load, which can be for driving a power-on LED indicator. Also be careful filter caps on the output; they often have max-cap limits in the datasheet. Anyways, they are easy to use. Connect the 2 input pins to your low-voltage supply observing correct polairty. For the DC-DC converter outputs, connect the *positive* terminal to your anode supply; the negative output becomes the bias supply for your current regulator(s). To make the anode current adjustable, connect a pot across the DCDC converter's output, then use the wiper to supply the bias voltage. I'd suggest 10-turn trimmers, rather than standard (cheap) 3/4 turn. - If you are using PNPs, be mindful of the base current. It may force you to use lower-value potentiometers (ie,below 1K). - If you use PMOS, there is no current so just use any pot you have; anything from 1K to 100K or more is fine. Best to add a zener diode to clamp any potential voltage spikes that could happen (startup/shutdown transients, ESD, etc) to protect the PMOS. The zener voltage needs to be greater than the DC-DC converters output voltage, AND less than the max Vgs specified in the PMOS datasheet. -- 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/f0928756-40c1-4d62-9c32-1ef20b28d743%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
