Hi Manu, I guess I could make a low-current voltage comparator on the secondary with= many megohm voltage divider comparing against a low voltage reference and = use that for feedback. Thanks for the links! Bob ________________________________________ From: piclist-bounces@mit.edu on behalf of Manu A= braham=20 Sent: Thursday, November 15, 2018 8:52 PM To: Microcontroller discussion list - Public. Subject: Re: [EE] Voltage regulation high voltage very low current Hi Bob, A combination of primary side regulation along with HV regulation might work quite well. I came up on this thread: https://rimstar.org/science_electronics_projects/electric_fly_swatter_zappe= r_racket.htm If it is possible to increase the output power by changing the resistor, decreasing it also would probably be fine. Saw a discussion on EDN. goo.gl/6iN9wN That could fire off some neurons. The BU508A is used in old CRT TV set's can go up to about 700V Cheers, Manu --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .