All you really need to acquire the spark signal is a bunch of thin wire wrapped around the spark lead. The pickups of a timing light are only fancy so you can take them on an off with ease. The changing voltage in the spark lead will be induced in the coil. You can read that with a DAQ card and sort out what constitutes a rise and fall of the signal (as opposed to noise) or pass it through a schmitt trigger to get a digital input. Either way you should put a good scope on whatever you use to pick up the signal so you know what you are dealing with. This solution probably requires less hardware ($) and more thinking.
Or you could buy a proximity sensor (an opto) and pick up some rotating part, or paint a spot on a rotating part and use some sort of photoresistor or similar, or you could glue on a magnet and use a reed switch, or a magnet with a hall effect switch, or a variable reluctance sensor and some rotating part of iron or.... Mike > -----Original Message----- > From: Lucamax [mailto:[EMAIL PROTECTED] > Sent: Sunday, February 15, 2004 9:05 AM > To: Info-LabVIEW Mailing List > Subject: 4 stroke engine Rpm sensor > > > > Hi all, > I need to acquire the RPM of a 4 stroke engine. > Either using a digital input or an analog input of my > acquisition board. > Some digital tachometers > <http://www.gpt.it/power_rpm%20eng.htm>use as > sensor just an electric cable with a clip connected to the > spark plug wire. > Any idea how it can be done in such way ? > > Thanks ! > > > >
