Recent content by Robert Jelbart

  1. R

    Car Tachometer

    I've had mine working for 6 years now and re-visited because I'm about to make another. That circuit was probably cribbed from somewhere else on the net and the error introduced. I found the same circuit with a 50 uA (Micro-amp) meter NOT 50 Ma. With 200K that would work. But a 50uA meter is a...
  2. R

    Car Tachometer

    A milli-ameter in series with a resistor is a voltmeter. So don't go looking for a voltmeter. This circuit requires a 1 ma meter. The 200k pot makes it a voltmeter with a 200v range (!!). I would suggest that 10K (or 20K) would be more suitable 50ma meter mentioned in the text must be a...