What would be the best way to limit current for an 80v DC circuit?

[JohnBee]

I'm working on small circuit that requires 80v DC with a current limit of 15 mA respectively.


With that said, does anyone have any recommendations as to what the best method to limit the current with this particular voltage?
I have used current limiting diodes in the past with good success, but the voltages were lower. However with 80v DC, the diodes cannot handle the wattage.


Thanks in advance for any help you may have to offer on this.

[danadak]

Something like this -

http://www.physics.unlv.edu/~bill/PHYS483/current_lim.pdf


http://fritzing.org/media/fritzing-repo/projects/h/hotwire-foam-cutter/other_files/external%20current%20limiting%20circuit.pdf


http://www.circuitstoday.com/controlled-transistor-series-regulator-with-overload-and-short-circuit-protection



Regards, Dana.

[Zero999]

There's an error in your units: mAh is a unit of charge, not current. A battery charger circuit which delivers 7.5mA for two hours would be delivering 15mAh.

How accurate does it need to be?

What voltage is expected across the load?

If you have 6V of headroom or more, then the LM317 can be used with a cascode on the pass transistor, to work at higher voltages than 40V. For 15mA, R1 = 82R and R2 can be much higher than 4k7, shown below: 47k will probably do. Tr1 needs to have a sufficient safe operating are to take 15mA, at 50V.