Tachometer signal multiplier

MikeMl

That schematic looks like:

"The frequency range of the output is about 233Hz to 2.33kHz (800 RPM to 8000 RPM). I would use a Phase Locked Loop (PLL). The Voltage Controlled Oscillator (VCO) must tune the range 233Hz to 2.33kHz. Feed that to a 4bit binary counter (wired as a divide by 16) and then use a phase/frequency comparator to compare the (VCO frequency)/16 to the input pulse rate from the engine.

This could be done with a couple of ICs, like a CD4046 or even the old LM565, plus a CMOS four bit counter."

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ClarkAE said:

Hi there, thanks you for doing that it is very much appreciated I look forward to seeing it. My e-mail address is daniel@clarkae.co.uk

I have also just been sent this diagram using a slightly different method to the one you describe, it will be interesting to compare the two methods.

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ClarkAE said:

Hi Mike, yeah I think that circuit seems to be the way forward, a few people have suggested the same method now. I will give it a go and let you know how it goes, thanks Dan

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tcmtech said:

The simplest way is to use a LM2907 frequency to voltage converter IC and then use its variable voltage output to drive a LM566 voltage to frequency converter IC to convert it back to a new higher frequency signal. I made one a few years ago to convert the low frequency speed sensor signal on a 1985 F150 to a higher frequency so that I could run and aftermarket electronic transmission in it. The electronic transmission needed a much higher input frequency than the stock cruise control sensor supplied.

Its a relatively simple circuit to make and calibrate.

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