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Thanks for the responses guys. I had a little play last night. I discovered that if I measure AC volts between +12v and the ign coil (-), I get a voltage that varies with rpm. I get around 5.19v at idle. This goes up ROUGHLY 0.2v for every 100ish rpm change. If I could lay my hands on a decent tacho, I suppose I could plot a calibration curve. Another idea I was given by a friend is to use a small electric motor with a wheel/ pulley on the shaft (like out of an old cassette recorder) and hold this against the gen drive belt. This will make the electric motor act like a generator, allowing me to measure DC volts direct from the small motor terminals. I'm going to have a go at doing a circuit (freq - volts conversion) like Shad suggested. I'll have a look in Maplins for a similar IC. Cheers, Gary M Essex UK -----Original Message----- From: Miller, Gary (G.) [mailto:gmille46@ford.com] Sent: 24 September 2001 15:47 To: Type3 (E-mail) Subject: [T3] Digital Multimeter as a RPM indicator? Hello, Does anyone know if it's possible to use a digital multimeter as an engine rpm indicator? I don't need a value in rpm, I just need a comparative indicator i.e. engine setting A has higher rpm than setting B. Could I measure current flowing through the points? Does this change with rpm? Part of me says it does, but the other part keeps shouting 'how?' This is for setting the idle mixture on a pair of aftermarket carburettors in my 71 squareback. The tacho I have does not have the resolution for such measurements. Many thanks, Gary Miller Essex UK ------------------------------------------------------------------- Too much? Digest! mailto:type3-d-request@vwtype3.org Subj=subscribe