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."
"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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