Help! Need ideas for a door opening circuit.

Thread Starter


Joined Oct 31, 2012
Hi there,

I am fabricating an automatic door opening design. It is basically a box with a 'wedged' cover that vertically lifts up and slides out of the way at the end of operation, automatically. To start the operation again, the user pulls the door down and it 'click-locks' to a 'solenoid' that will release it at the end of the operation. I have most of the mechanics (hinge system) done. Now i need your expertise on a circuit to use.

I need the circuit to energize a solenoid (for about 1-2 sec) AFTER a 24vdc line (a shutter) has been shut off. (This will release the door.)
For the last 8 to 15 seconds of this operation, there is a 24vdc line (the shutter) energized. I want to detect when the 24vdc line (shutter) is DE-energized, THEN supply a pulse of 1-2 seconds to the solenoid. (Door Open)

Available voltage to use is :
1. a CONSTANT 24vdc (I could make a 5v for chip power, no problem)
2. the 24vdc line of the shutter (detection should occur on the edge of de-energized.)

Flip-flop?, Latch?, just not sure where to go from here.
The solenoid was going to be 24vdc because of power availability, but it could be lower.