Locksmiths Both Feared and Admired Elmer

By: 
August 16, 2004

After locking the door and leaving the keys inside one too many times, Elmer hit upon an entry strategy that involves no keys or codes to remember. He simply attached a timer to his door-bell, and a timer relay to the key switch terminals on the opener for the door on his attached garage. The doorbell operates normally, except when it is pushed continuously for 12-15 seconds, which automatically opens the garage door. Of course, if neighbors or friends find out, you're no longer secure!

For PDF links to Elmer Jones' instructions and drawings:

Schematic drawing of door bell activated delay garage door opener

Circuit board drawing

Doorbell timer drawing

Keyless entry system parts list
Amt Part Description Allied Part #
5 Diode 1N4148 950-1550
2 Disconnect female-12-18 AWG 617-1481
1 Capacitor 220muF25V 852-7030
1 Capacitor 47muF16V 852-7002
1 Capacitor 470muF10V 852-6500
1 Op amp LM741CN 263-0134
1 Reed relay 5V SPST, N.O. 681-0005
1 Resistor 0.5W. 560O 832-8315
1 Resistor 0.5W 680O 832-8330
1 Resistor 0.25W. 22KO 832-0585
1 Resistor 0.25W. 82KO 832-0703
1 Resistor 0.25 120KO 832-0727
1 Enclosure (1 x 1.5 x 2.5 inch) 736-0061
1 Switch, rocker - mini 676-0032
1 Hook up wire 22 AWG solid 696-9282
Additional parts required: Attached garage, garage door opener, common doorbell, circuit board, solder 1lb 60/40, 21Ga.

Comments (0)

Please log in or to post comments.
  • Oldest First
  • Newest First
Loading Comments...