Hi,

I have a 12V fuzzlight that uses about 0.4A current. I'm trying to run it from a 1A 30V transistor (with flyback diode) on a 12V supply. After about 2 minutes the motor suddenly slows down and the bulb fades out until it's completely off.

At first I thought I was overloading the transistor but I've measured the current draw on 2 different bench PSUs and I'm always getting around 0.4A which I know these transistors can handle easily.

I attached a scope to the fuzzlight. The motor appears to be causing some spikes about 10V above the supply voltage so I've added a 13V zenner diode which seems to have solved the spikes but not the overall issue.

If I turn the transistor off and back on then the fuzzlight comes back on full speed/brightness and lasts from a few seconds to a few minutes depending how long it's been off for.

Has anyone seen anything like this before? I'd like to solve it without using a relay if possible.