Magic smoke is shop humour built on a mock theory: every component is packed with smoke that makes it work, so it dies the moment the smoke gets out. Engineers and technicians say a board 'let the smoke out' after overvoltage, reverse polarity or a wiring error on first power-up. The phrase marks a failure as obvious and destructive rather than subtle.
Wired the 24 V supply onto the 5 V input and the controller let its magic smoke out on the first try.
Also heard as
- let the smoke out
Related terms
ESD
Electrostatic discharge: sudden flow of built-up static charge that can destroy or upset electronics.
Inrush current
Large transient current drawn when a transformer, motor or capacitive load is first switched on.
Bump
To energise a motor for a split second to check its direction of rotation before running it properly.