Fuzzlight fades out when running from a transistor

[Dave]

An actual schematic would be nice.

[The Master]

Hi, Sorry for the delay. I've managed to solve it and it turns out it was my own stupidity.

I was testing with 2 power sources (additional to the bench supplies).
1 of them has 12V regulators in and was actually designed for turning small solenoid valves on for a few seconds.
It looks like the fuzz light was drawing enough current to cause the regulator's thermal protection to kick in (hence the slowing and dimming).

The second source is unregulated and uses 20V 1.2A transistors running from 12V toroids.
Originally the spikes caused by the motor were blowing the transistors as they were hitting 25V so I added the 13V zeners.
With the zeners in place the transistors were blowing immediately after turning on.
Eventually I remembered that the house gets 250V+ mains so my 230 to 12V toroid is actually outputting over 13V.

I'm already in the process of converting everything to use 12V switch mode supplies and have had a fuzzlight running for over 12 hours without a problem.