Kussmaul Electronics makes such units. Employ a solenoid to eject the cord =
on a key to start, for both compression & spark ignition engines.=20

-MK

-----Original Message-----
From: On Behalf Of Dwayne Reid

One of the projects we did many years ago was an automatic block heater cor=
d unplugger.  The female end of the extension cord was plugged in as normal=
..  When the engine was started, a screw mechanism retracted the blades of t=
he male plug and caused the female end of the extension cord to simply drop=
 away.  Really cool and worked quite well - but I never heard anything abou=
t it after we had built the proof-of-concept prototype.

As I recall, the screw mechanism was driven by the motor assembly from a re=
ally cheap Chinese-made hand drill.  The engine running detect was done by =
wrapping a wire around one of the spark plug wires.  Pretty simple stuff, r=
eally.  But the customer was ecstatic when he got it.

dwayne



--=20
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