pulse frequency to smooth dc voltage circuit

[Eric]

Hello,

This is my very first post in your forums and I am hoping that someone can advise me on how to solve the problem of converting a pulse of variable frequency, but fixed pulse width, into a variable but SMOOTH DC level.

I am playing around with a circuit which operates an ignition coil on a motorcycle. and I want to monitor the pulses from a Hall effect device in order to create a "tachometer" type of circuit but one which seems, as far as i can see, to differ in one major respect from any of the circuits that i find on the web. These circuits seem to create a very raw dc output of some type or another. but i want a nice steady dc voltage which increases linearly ( ideally ) in response to the pulse frequency from the hall trigger. I want to use this dc voltage ( if i can obtain it ) to activate an advance/retard style of pulse shaping circuit.

the pulse waveform from the hall switch is a nasty shape of waveform to work with but hopefully someone has met and solved my problem before.

Can any of you experts offer any advice ?? PLEASE ?

Regards

[Author]

Posts