Voltage Divider Cooling. Needing heat help.


Thread Starter


I made a voltage divider to power a stepper motor. It requires 9V and I am using a 12V wall plug.

If you have used one before, have your experiences shown that your resistors get pretty hot to the touch?
We do not know enough bout the voltage divider.
No data on the motor.
Think about the power going into the motor. The power in the resistors is 33% of that. See how large the motor is and how small the resistor are. Yes they will get hot.
Yes. You are definitely dumping too much power on the resistor. And I would assume your giving more power than it is actually rated for.
You could try an LM317 to get the needed 9V. Probably would still need a heatsink but it will definitely be more efficient.

If you really want to work off the same circuit, try a resistor with a higher power rating (1W or 0.5 W).


I did the math and using a multimeter see that with my 33 Ohm and 100 Ohm resistors I am indeed getting around 9V, but noticed that the 100 Ohm resistor gets incredibly hot. Is this to be expected in a voltage divider?

Is that relatively normal for the second to get so warm?
Then some simple ratio mathematics or Kirchoff's law so that they can work out current through the resistor divider network.

This way we can see what's been calculated. Or, could be a problem with the circuit itself.
What are the voltage readings? Graphed waveforms? Could you share some plot rednerings?

That would be helpful.
Let's bring this back to the stepper motor.

A stepper motor doesn't just magically work because of the DC source. You're going to need a control IC or transistor to get the motor to turn a certain amount. Back to basics.