Control circuit for electronic door lock - has RC delay circuit allowing time to open door after depressing button

摘要

The control circuit, for an electronic door lock, only unlocks the door whilst its electromagnet is actuated and has an RC delay circuit to hold the lock open long enough after the button has been operated for the door to be opened. The operating button contacts connect the RC circuit to a 50 Hz 12/20V supply. This supply is rectified and applied as dc via a transistor switch to the electromagnet winding in the electronic lock. A second rectifier is included in the RC circuit. The RC circuit contains a variable resistor connected to the base of the transistor switch.