So if I was to use a 5.1 volt Zener Diode: https://www.jaycar.co.nz/5-1v-1n4733-1-watt-zener-diode/p/ZR1403You can use a five volt zener diode to limit the voltage across the opto. That has been my point all along.
See post #41modified by bertus. This is all you need.Attached is what I now have.
Okay, so the 2.7K resistor will reduce the current to protect the opto, and because the opto's also have a diode within them, they will only work when the DC current is one way - thus removing the original diodes from the circuit is possible (even though this may mean up to 36 volts will be entering the opto's ?See post #41modified by bertus. This is all you need.
No, that circuit is not what will work with the zener diodes. And it seems that I am not able to see the circuit that you have. I am on a different computer now and the circuit that I am seeing will not work with the zener diodes because the two opto-isolators are tied together. If that works it will be simpler than what I am suggesting. And replacing the resistors with the 1N4733s is not what I was suggesting. With the two optos tied as shown adding the zeners will not work. So ignore my suggestion if you use the circuit shown.So if I was to use a 5.1 volt Zener Diode: https://www.jaycar.co.nz/5-1v-1n4733-1-watt-zener-diode/p/ZR1403
Instead of the 1N4007 Diode: https://www.jaycar.co.nz/1n4007-1a-1000v-diode-pk-4/p/ZR1007
Then this would limit the voltage going into the opto to 5.1 volts maximum (regardless of the input voltage being 14 up to 36 volt), and therefore could also remove the 2.7K Resistor from the circuit as well ?
Attached is what I now have. The right is existing in place, the Zener Diode and Opto are to be added to the circuit.
Cheers
Kent.
Yes. The voltage is not an issue it's the current.thus removing the original diodes from the circuit is possible (even though this may mean up to 36 volts will be entering the opto's ?
Hello,
The circuit can be made a little simpler.
As only one opto is active, it will protect the reverse opto from over voltage.
I have taken the image from @sghioto and modified it:
View attachment 226196
Bertus
Yes. The voltage is not an issue it's the current.
Again post 41 is correct, no zeners or diodes required.
I just did more testing - mu Multimeter shows the voltage briefly dropping down to about 9 volts for a brief moment when the motor changes speed. It's hard to know for sure as the multimeter takes a bit to show a voltage stop.Possible the voltage is erratic. It should still function with only 14 volts.
Possible fixes: Reduce the 2.7K resistor to 2.2K
Add 1uf capacitors across the 10K resistors R4,R6.
Sorry, I meant 106 16+ capacitors.I have some 106 10+ capacitors - will these do ? (I'm assuming that the 16 is 16 volts, and the 106 is their uf rating ?
The resistors are what Numato support told me to use - there is a 2.2K in addition to the 1K and 0.39k.
10uf might work if you raise the resistor values to 27K and 10K
0.5 watt10uf is correct and might work if you raise the resistor values to 27K and 10K.
Meaning R1 and R5.
by Jake Hertz
by Duane Benson
by Jake Hertz