Originally Posted by David M
Good point Bill. I had an old modified square wave inverter which "let the smoke* out" of a couple power converters...
* “Magic Smoke” refers to smoke released by malfunctioning electronic circuits.
The magic smoke is observed to come out of electronic components when overheated, often through exposure to an extreme electrical current
usually caused by the application of excess voltage through some failure of the circuit.
Manufacturers put a little bit of magic smoke into every electronic component, and it is this smoke which makes the device work.
In support of this theory, once the magic smoke has been released, the device lacks its key component and no longer works. The smoke thus can be thought of as an essential part in the device's function.
It is also noted that once let out, the magic smoke cannot ever be put back in.