By the way, I always thought it was interesting that the three resistors making up the voltage divider that drives the comparators in a 555 were all 5k. Is that where 555 came from? So far, people I've talked to who were apparently with Signetics when it was introduced say it was not based on that. But, I thought it was an interesting coincidence. Harold --=20 FCC Rules Updated Daily at http://www.hallikainen.com - Advertising opportunities available! Not sent from an iPhone. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .