A solenoid is a very simple device: a wire coil that surrounds a rotating shaft. Putting electric current through the coil forces the shaft to turn. Brandstrom offers two types of solenoids: Self-Restoring and Bi-Stable. Here is the difference between them:
Self-Restoring Solenoid
Click & hold the power button to test.
A Self-restoring solenoid is one where the shaft turns to its active position when a steady electric current is applied, and turns back to its original position when the current is cut off – like a door on a spring that closes itself when you let go of the handle.
Bi-Stable Solenoid
Click & release the power button to test.
A Bi-stable solenoid is one where the shaft switches between two positions when an electric current is applied – that is, an electric pulse makes it turn from left to right and stay there when the electricity is off; a second electric pulse makes it go back from right to left and stay; and so on.