Afternoon,

Electrics is not my strong point I'm more of a mechanic, I need to take an electrical signal which is counted and make 2 pulses appear as 1.

If you are wondering what I'm doing: I'm trying to use a motorcycle rev counter on a car engine as it is considerably more compact but as I'm using a V8 it fires twice as many times as the 4 cylinder engine it was designed for.

I guess its a very simple circuit, all and any help greatly appreciated.

Thanks

Alex

 

The devil is in the details. If you had logic-level pulses available, all you would need is a toggle flip-flop, which divides frequency by two. The hard part is getting from whatever your input is, to a logic level pulse. This is going to be difficult without a hands-on look at what you have.

 

All I know is that a 12v pulse comes from the distributer to trigger the coil to fire a 50000v charge back to the distributer, that is then sent to each spark plug in turn.

what is a "logic level pulse"?

 

A logic level pulse is in the ballpark of three to five volts when high and les than half a volt when low.

If you you can tap off the 12v coil i/p and use a voltage divider to bring the sampled pulse down to this level, then you might be able to divide frequency with the flip/flop and then amplify flip/flop o/p for the tachometer to use.

You will need to know about voltage dividers, also flip/flops, simple amplifiers, and possibly de-bouncing.

voltage dividers

Flip/flop used to divide frequency by two

Table of Contents for Amplifiers Chapter

De-bouncing