Good day to all. I'm re-visiting a recent project where the customer requirements have=20 changed. The original project was a bog-simple SPDT photo-MOS relay=20 that is operated by a ~20 - 28 Vdc input signal. The relay control=20 signal is tapped off from the starter solenoid on a large=20 earth-moving machine. The battery voltage sags down to about 20V=20 when the starter is engaged. There is continuous 24Vdc available but it is a fairly major hassle=20 for the installers of this box to access that continuous 24V=20 supply. So the customer would prefer that I implement the following=20 change using only that momentary 24V signal that is already present in the = box. What they want now is for the relay to remain changed over to the=20 "start" position for some time period (as yet undefined) after the=20 input signal has gone away. It's obviously pretty simple to do *if*=20 I had a continuous supply rail available. But I don't. So I'm planning to just store charge in a (very) large=20 electrolytic capacitor and have that feed the timer. I definitely=20 need to have a well-defined ON to OFF transition - the photo-MOS=20 relay behaves 'funny' when the LED drive is in the un-defined current=20 range between guaranteed OFF to guaranteed ON. The problem is that the minimum LED current is 10mA. My saving grace=20 is that I have a nominal 20Vdc available to charge the capacitor. I *could* just use a two-transistor linear constant-current=20 regulator. Two problems with that: the regulated current changes=20 with temperature *and* it wastes a significant percentage of energy=20 as heat. So I want to go switch mode if I can do it easily. It occurred to me that there must be an enormous range of=20 constant-current switch-mode LED drivers available. But my couple of=20 hours searching has not found anything that I can purchase easily=20 from Western Canada. In other words, I'd like to find something that=20 I can purchase from Digikey or Mouser or Newark or Future. My best guess is that I'm not using the right search terms. My requirements are: 28Vdc max input voltage 10mA output current works down to -45C or colder readily available from North American distributors Does anyone have any suggestions? Many thanks! dwayne --=20 Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing --=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 .