In a previous question I posted to the exchange I asked for some instructions on trying to variable speed control a motor. Someone suggested utilizing PWM from my Arduino to open and close a Darlington pair to control speed. I wired it up and ended up frying my darlington pair. I am afraid that I screwed up something with the flyback diode... I am not certain. I am not sure where to trouble shoot what I did wrong. The transistors and flyback diode were very hot to the touch.
What kind of ratings and type of diode should I look for when looking to eliminate flyback voltage from a 18 VDC, 1.5 motor? How would I wire this correctly when using PWM from an Arduino to control a transistor pair?
I am a very new hobbyist and am having trouble wrapping my head around this issue.
Answer
Diode was probably inserted backwards around the motor - the purpose of the diode is to bleed a current spike from the motor's inductance, which flows opposite direction.
The diode has a line/bar that indicates the cathode - this side needs to be connected to + side of the motor.
You might need to replace the darlington and diode, unfortunately.
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