Usually, Pulse-Width-Modulation, not simple voltage, is used to control the speed of a DC motor. Then the speed does not change much when the load changes.
Your power supply voltage is 3 times too high but additional circuitry can reduce its impact.
I would prefer to use voltage to control the motor speed because the LabView interface of the analog output is easy to implement. I must use the daq board since the motor is part of a bigger experimental setup. The setup includes other sensors; the data acquisition and the motor control have to be made simultaneously.
The load of the motor will be constant.
Regarding the power supply, the voltage can be varied to meet the maximum voltage of the motor.
Here's a simple voltage-controlled PWM circuit using a 555 oscillator and a comparator. You can put the control voltage at the comparator input instead the pot.
Here's a simple voltage-controlled PWM circuit using a 555 oscillator and a comparator. You can put the control voltage at the comparator input instead the pot.
As I'm not used to some components, I have a doubt about how to connect my control voltage in the comparator instead of the potentiometer. Also, do you find that it is necessary to isolate the daq control circuit from the circuit that powers the motor? If so, how do I do this isolation? By an opto-isolator?
I found this **broken link removed** that pretty much does what I need, but again, is it possible to use my control voltage?
If you do not connect the negative from the control voltage to ground then the (+) input of the comparator will not have any control voltage and will not work.