If you put a 5v 78L05 regulator across a resistor, it becomes a constant current device. A pretty cheap way of doing it, maybe easier to get than a constant current diode. You get the constant current, IIRC, out of the ground pin with the resistor connected between the ground pin and 5V pin. -- Lawrence Lile Lile Engineering Embedded solutions and industrial controls Harold Hallikainen Sent by: pic microcontroller discussion list 06/24/2004 03:37 PM Please respond to pic microcontroller discussion list To: PICLIST@MITVMA.MIT.EDU cc: Subject: [EE:] Constant current diodes or FETs? I'm loooking for a two terminal constant current device that could be put between an LED and a variable DC supply to hold the LED current at 5mA as the supply varies over a 0-10V range (recognizing we're not going to get it at 0V, but I'd like the widest range possible). So far i've found the Central Semiconductor CCLM5750 which is a nominal 5.750mA, but it takes 4.5V to get 80% of the rated current. Anyone have other ideas? THANKS! Harold -- FCC Rules Online at http://www.hallikainen.com -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu