From: "Kelly Miller" To: Sent: Monday, September 22, 2003 7:10 PM Subject: [EE:] Newbie Question: Electrical protection for PICs > I understand that 5 volt PICs work with what seems low voltage and > limited current. Is it a good idea to put some sort of electrical > "fusing" between a regulated 5 volt power supply and the PIC input > pin(s)? (There is a 3 Amp circuit breaker in the upstream 12-16 volt > power supply that I regulated down to 5 volts.) Would it serve to > protect the PIC, associated components, and possibly safety? At 5V, you have no problems with safety. Your body is far too resistive (if I may be so bold) to pass much current at that voltage. As far as the PIC goes, it has internal resistance that will protect it, provided you don't put it in backwards, as another poster mentioned. I think the "fool's diode" is to protect your entire circuit if you connect the power supply lines the wrong way. The current goes through the diode rather than through your circuit the wrong way, and (hopefully) causes the breaker to trip. Regards, Bob Monsen -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu