Very very electrical question., Tachometer waveform Options

[sgomes]

Ok, I don't expect to get an answer to this question but here goes nothing:

I've got this fancy tacometer drive thingy that is supposed (IMG:style_emoticons/default/unsure.gif)

Assumptions about the tach:

It expects at least +5V pulses more is ok.
It assumes a four cylinder engine.

My assumption on how tachs work:

You get one pulse for every spark. So.....

assume 6000rpm for the sake of argument
6000rpm= 100 revs per second * 60 seconds
4 sparks per revolution.
4 * 100 = 400 pulses per second.

I've got something close to 200 pulses per second comming out of my sender at about +10V.
The tach isn't moving.

[sgomes]

Bowlsby (Jeff? isn't it?) :

Yes, I could just figure out what the RPMs are and shift on speed only. The engineer in me just wants more info! Also, and more importantly, this device is also a rev limiter. Series DC electric motors have this neat feature called "runaway" where it takes less and less current to go faster and faster. (IMG:style_emoticons/default/ohmy.gif) You need to be able to cut off the "fuel" before it detonates.

James:

You're right it doesn't need a gearbox. I'm not a mechanical genius like you guys so using the stock gearbox solves the problem nicely. Otmar's electric 914 is proof you don't need anything more than third. He has a 915 gearbox and the shift linkage isn't even in the car! (IMG:style_emoticons/default/blink.gif) Hell, you don't even need reverse! Just run the motor backward!!! (IMG:style_emoticons/default/aktion035.gif) I however like to have two gears. 2nd for around town and third for winding it up on the freeway. It's also a bit easier on things if you still use the clutch for staring out from a stop. You don't have to but it feels less like someone just rearended you! (IMG:style_emoticons/default/rolleyes.gif) The thing that is really hard to get used to is not using the clutch when you come to a stop! I swear you think you've stalled the car every time! No sound!

BIGKAT_83:

PM is on its way! I signed on this morning to ask that very question! I love this club!