Have you considered PWM? This is the technique LED signs use to fade on and off. Win Wiencke Image Logic Corporation ----- Original Message ----- From: To: Sent: Friday, July 25, 2003 1:50 PM Subject: [EE]: DAC advice I need to fade on and fade off like 20+ LEDs, and I need to do it as cheaply as possible. The fade on and off should be quick and smooth. Right now what I'm working with is this: some 8 bit DAC hooked up to a PIC which will count from 0 to 255, then back down again on one of the ports that's connected to the DAC. I have some questions: Is there any cheaper way to do this without the DAC or PIC? What is the cheapest DAC you suggest? Maybe a multichannel one would be cheaper? Would it be better to get a DAC that changes voltage or current? Any ideas/suggestions would be great. Thanks! -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads