On Mon, 13 Oct 2008 15:33:32 -0700 (PDT), "tBot" said: > On a snare drum playing robot, I'm driving a number of continuous duty > solenoids. They're running at 48VDC, being triggered by logic-level > signals > sent from a microcontroller through ULN2004A Darlington arrays. At 48V, > each solenoid draws approx. 350 mA, so they're well within the > per-channel > current limits of the darlington arrays. The 2004 is intended to be driven from ~15 volt logic. The 2003 is for 5 volt logic. The voltage and current together are both a little high. You must use some form of snubbing. And if you intend to use a quick snubbing method you will need to dump energy at a higher voltage. I think you need to look for better parts. You might be able to find a drop-in that is rated at a higher voltage and then use a big zener on the common line. You are right at the limit for that part, I'm not surprised it's dying. Cheerful regards, Bob -- http://www.fastmail.fm - Accessible with your email software or over the web -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist