Okay I have done the test, 12 volt battery measures 12.7 volts, separate 5 volt supply for PWM input. Output reads 9.3 volts maximum .
When using Estlcam to send the signal same high level of 9.3 volts at s24000 and 5.3 volts at s12000
I can make the lower reading 5 volts by adjusting the pot, but then the higher volts drops as well.
Can the nano deliver enough milliAmps to bring the booster up to 10V?
Without a scope it is impossible to work out exactly what is happening Reg. All I can suggest is you try a different board - maybe the ones Dave L listed. As you can see from the circuit suggested by Estlcam, it is not complicated and if the ones you have cant be adjusted to 10v @ 100% PWM off load they are no good.
Then you get to configuring your VFD for analog input on the connectors and not the buttons on the front panel!
The current is not what drives the op-amp, it is the voltage. The LM358 uses nanoamps of input current. (three fifths of sod all!)
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How would I test with a scope Mike? What is the proceedure?
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Not received Mike
It ended up in a new thread???
Anyhow… my reply -
I would be looking at the input signal to ensure it is actually 5V - 100% PWM. Then I would be looking at the output voltage waveform to ensure it is not excessively noisy and is actually 9.something volts as your multimeter suggests, then, it they were ok I would be looking at the feedback voltage going to the opamp negative input pin 6 and comparing that to the positive input pin 5 to check opamp is working at the correct voltage level and then possibly deciding on a suitable bias resistor to drop the feedback voltage a bit to increase the opamp output.
It is not impossible that all the boards you have were from the same batch of rejected boards because an incorrect component was used during assembly, the simplest solution would be to try a different seller and a different board.
Yes you are right, I got a batch of stepper drivers that were all bad. I lost a lot of time trying to find the problem only to find out that they were all no good. Replaced with different drivers and all went perfectly with no other changes to the wiring or setup.
It could be the same with these small boards too, they were all purchased at the same time so they could all be from the same batch.