Spark wire pickup needed for a Tachometer

If it was me, I'd head to Harbor Freight (a cheap tool store) and buy the cheapest timing light I could find that had a clamp-on inductive pickup, and dismember the thing.

Tom

set points with a guage, then pinging means retard the dizzy, and I always do it backwards having the richess dizzy setting. otherwize buy one, they're only cheap, and probably more cheaper than you can build one.

and i didnpt mean turn the dizzy too far that it dont start

oh, I just pulled out my old multimeter, for some reason I thought you meant dwell... :s.-cuzzy

All you need is a large clothes peg- fit a split toroid ferrite in- wind enough turns of coil wire around toroid to trigger your device (ie, an inductive pickup).

Fluke model 88 89 or better. Does RPM and comes with clamp in kit.

Use a Hall-effect type transducer. If you google go-kart tachs, you will find several companies that manufacturer a cheap sensor type tach that you are looking for. Just tie-wrap the sensor directly on one of the spark plug wires and calibrate the unit. Most all of these tachs come with a dro.

Hi - if you only needed to read rpm, you could try looking up 'tinytach', Oppama or Ono Sokki. I have used their products before with success. tinytach and oppama wrap an antenna wire around one spark plug as a pickup. But, you say you actually do need to do something with the rpm, so there are several ways. I had one of my guys build a small transistor cct using the pickup wire wrapped around a plug wire to give me a pulse stream to feed into a data aq. unit. You can also interface a pulse stream from the pickup to an industrial 4-20mA signal conditioner to interface with your testing unit. The easiest solution we were able to implement for small engine testing was a strip of reflective tape on the flywheel being picked up by an industrial optical pickup. Pretty low-cost and very effective. I don't recall exactly, but Tinytach may also be able to build a unit with a 4-20 out - you'd have to call them to ask (the brain has had too much time baking under hot vehicles and sucking in exhaust fumes). We have also pigybacked off of the engine's own rpm pickups from the flywheel.

For in-vehicle testing, we now take the rpm from the can-bus and either integrate it with our data set, or post-test combine the can file data with our sensors data from our data aq. If you are building a Labview based control system, this is a good way to go provided there is a bus to extract signals from...

Good Luck,

AndyC.