That being said, all you need to do is add a 1k resistor from pin 5 of the 4N35 to the arduino +5V
and then the analog pin will read voltage.
But do you really want to measure voltage ?
Is there any doubt that the voltage you measure is going to be 5V (correct answer: no)
My apologies, I was going based off of a circuit I had found here, I mustve not copied it over right into my notes:
I’m not too familiar with datasheets, and as far as understanding the diagrams explaining the chip goes is not good as I’m new to making circuits. From what you’ve told me I went and simulated a circuit that I believe would be okay to use. So that square wave output of high and low would be something I could use to measure the frequency?
how on earth you arrived at 1190Hz will be interesting to learn
I was going based off of this post’s frequencies, I figured the frequency was what came from the alternator’s W terminal.
I also found the same frequency posted here:
A tachometer converts mechanical power into a small electrical signal for measuring rotation speed - yet you
talk of “driving the tachometer” from an alternators W terminal?
Do you mean you are trying to drive a tachometer’s meter unit? IE replace the tachometer with a different signal source?
The tachometer I’m trying to drive is an old three phase gauge from an airplane.
What I’m trying to do is take the W signal from the alternator (one AC phase wave) to measure the frequency of the pulses, divide that by the difference in terms of alternator pulses to crank rpms, generate a pwm based off of this new frequency which will go into the ESC and ‘drive’ the three phase tachometer.
So essentially, Alternator AC → Arduino -(PWM)-> ESC → Tachometer
I’m just looking for a good circuit that takes the Alternator’s frequency and makes it safe for the Arduino to read.