I would still think that ON vs. OFF noise characteristics should be quite distinctive. I'd take a look with a 'scope and see what you get. If you AC couple the signal, amplify and digitize it you could run an FFT and get some idea of the spectral characteristics. Bob Ammerman RAm Systems ----- Original Message ----- From: "Herbert Graf" To: Sent: Wednesday, December 03, 2003 5:33 PM Subject: Re: [EE:] Voltage measurement > > The voltage produced by an alternator in a running car will have about > > 10-15mV of DC ripple on it. Battery voltage is quite flat. > > Unfortunately I don't think that's as simple a solution as it sounds since > other devices can generate noise. For example, I regularly have an inverter > pluged in to charge batteries while the car isn't running, that inverter > surely inserts an amount of noise into the cars electrical system (I can > hear it from the radio). TTYL > > ---------------------------------- > Herbert's PIC Stuff: > http://repatch.dyndns.org:8383/pic_stuff/ > > -- > 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