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."

 

[ClarkAE]

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."

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

 

[DirtyLude]

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.

There's not much to compare. They are more than slightly different. Mines a microcontroller solution. I originally did this as it had to support both frequency doubling and frequency halving. It's simple to make if you know microcontrollers, but hard to do if you don't.

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

If you are going to make your own, there's not much reason to send you this one. If you aren't able to get it working, let me know and I'll send it then.

 

[newbiEE]

Would anyone happen to know how to take an input of 10Hz and multiply it by 37?

I need to have this done for my digital speedometer, and can't quite get this one down.

 

[ichristov]

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.

Would you be able to send me that schematic you used? I'm in need of exactly the same in order to get a '99 engine working 100% correct in an '85 car....

thanks in advance

 

[tcmtech]

Just download the two IC data sheets and build the circuits as shown.
Thats basically all I had to do.