My concern is that any sudden change or dip in the computer's 12volts, this could effect the performance of the PIC. The source that powers your sensor dips... so will this hurt you in monitoring that same dip? -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Brendan Moran Sent: Wednesday, June 26, 2002 5:50 PM To: PICLIST@MITVMA.MIT.EDU Subject: Re: [PIC]: Monitoring a voltage with a 16F877? the same voltage source?? ----- Original Message ----- From: "Brandon Stewart" To: Sent: Wednesday, June 26, 2002 2:33 PM Subject: [PIC]: Monitoring a voltage with a 16F877? the same voltage source?? > ==> My question is, should I worry about sensing a voltage that is > providing the power to my PIC to start with? Remember, I am monitoring a 5 > & a 12 volt line, and this 12 volt line is the same one that powers my PIC > through a 7805. If you choose the right resistor values, you can normalize the nominal voltages on the 2 lines to the same value (2.5 I think you said?) which should make your software slightly less complex. Since the power is going through a 7805 and is comming from a computer powersupply, you should be fine. You're running through a 7805 so as long as the 12V supply doesn't drop below about 7V you should be OK. The power supplies on computers can in general supply in excess of 5A, and since your dissipation should be in the order of milliamps, you should be OK. -Brendan -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads