Cheapest and easiest way to slow down a motor

[Alan Anderson]

Originally Posted by sanddrag

What is the cheapest and easiest way to slow down a permanent magnet 12VDC motor (think Van Door motor)?

To "slow down a...motor" could mean several things. Are you talking about applying a brake to a spinning motor? The Van Door motor's gearing probably won't break if you put a high mechanical load on it, but the motor might overheat. If you want to stop a motor quickly, shorting its input does a good job.

Or are you talking about limiting the unloaded speed? Just give it less voltage.

I was thinking of wiring a halogen lightbulb in series.

That's probably going to give you fits trying to characterize the voltage drop across the bulb. Halogen lamps aren't very happy about being run at lower than their rated voltage anyway, are they? I'd just use a simple resistor, or preferably choose a lower supply voltage in the first place.