Mike wrote:

>Hi all,

>Can anyone give me any information on connecting the ignition coil of
>a car to a PIC input for the purposes of a tachometer.

>Cheers

>Mike

>men5m3b@electeng.leeds.ac.uk

Use a circuit something like this:


                                      1N4007 diode

  Ign coil input side (low tension) +
 ---------->I---------/\/\/\/\---------------------------- PIC or Monostable
                                                          __I__/
                                                         /       /\         5v z
ener
                                                          I
                                   ____________________I____________ negative of
 both car and PIC circiut
                                          //////
You may want to use a monostable as the input will have a lot of RF ringing on
 it.

Robert