A Solenoid Question

Originally posted by Richard Hughes
Thanks all for your replies and help.
The reason I thought solenoids were positive or negative earth is because I was told this by 2 different auto electricians.

Cheers
Richard Hughes

Hmmmmm, then perhaps you should use the term auto and electrician somewhat loosely in the case of these two people.

Lets be absolutely basic, a "solenoid" is a cylindrical coil of wire acting as a magnet when a current is passed through it. The term has found worldwide mis-use for a relay or contactor used to switch the high current supply to the engine starter motor.

A solenoid, when having a laminated iron core to intensify and concentrate the magnetic field, is called an armature; these are found in motors and relays/contactors.

Similarly mis-named worldwide is the ignition coil which is actually two coils mutually (by magnetic field paths) coupled together and is in fact a transformer.

R.