- Joined May 30, 2022
In order to use PWM to make a constant voltage of 0-12V you need to start with a voltage source that can provide at least 12 volts. The Arduino's power supply is 5V or maybe 3.3 volts. Those would be the maximum voltages you can achieve with PWM.I am trying to convert arduino's pwm output (0-255) to constant dc (0-12) based on the value of pwm at this moment (i.e. it can be varied later on). Is there an easy direct way to do this?
Using a LPF, and an Op-Amp could achieve the requirement voltage, but when connecting any device even a resistor of 1k, or 100 the voltage drop to below 5v!
What type is the op-amp?I don't know the difference between one RC filter and then Op-Amp, but I tried the second one (RC + Op-Amp) and it works, measured the voltage difference between the output of Op-Amp and ground, it was 12v as required, but when connecting any device across these terminals it does not work and even the 12v drops to 3 volt (could be higher or lower depending on the connected device but in all cases it was less than 5)
I'm not too sure about that. If it were simply a brushed DC motor than I would agree. Most computer fans have brushless motors and electronic drivers, which might not appreciate PWM. I would use PWM followed by an LC filter.You are better off to the run the fam from the PWM signal rather than convert it to a voltage, if that is your goal.
Sorry, I didn't realize you needed the whole design spoon-fed.you are not giving a clear schematic from the input to output including all values and simulation
look in the op-amp datasheet for the line stating the maximum output current. (Usually about 25mA), compare that with the current required by a computer fan (probably about 250mA)But the other two designs of Papabravo and crutschow uses an Op-Amp, so can how we confirm that the Op-Amp used will not be so useful with fans?
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by Jake Hertz
by Dale Wilson