On Thu, 2 Apr 1998 11:10:44 -0600 Michael Hagberg writes: >would this circuit work for a lawn mower tach, could the pick up be >just a >piece of wire wrapped around the spark plug wire a few times? The "kill" wire which is shorted to ground to shut the engine down should have a suitable once-around pulse of a couple hundred volts. In most lawnmower type engines, the spark plug fires once per revolution; the extra spark occurs during the exhaust cycle and doesn't hurt anything. Of course the tachometer needs to be sure not to load the ignition down to where it doesn't work. Inductive or capacitive pickup from the spark plug lead could also be used. Many of the electric-start engines have a flea-powered "alternator" driven by the flywheel magnets that would provide a nice low-voltage, low-impedance signal directly proportional to the engine speed. _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866]