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Automated Garage Door Timer Answered

I have the bad habit of leaving my garage door open sometimes. To come home with your garage wide open is pretty scary. So I was thinking of this idea... 

The garage automatically closes after 5 minutes. But that's pretty annoying so I figured you could install a switch underneath the garage door opener that will leave the garage door open. Any ideas on how this could be done or more suggestions? Thanks!


You want a delay timer wired in series with your door opener using relays.  However, because the same button tells the opener to both open and close, you can't do it by way of the control box.

Look up "delay timer" on Google to find numerous examples of the components you need.  Set up a circuit with a latching relay, the relay output going to the delay timer, and the timer output going to the input of a second relay.

Here's one idea.  On the main control board for the opener (that is, inside the motor housing), you need to find the lines which drive the door to open, and to close.  Take the door open lines and tap off them to the input of the first (latching relay).  When the door is opened, the signal will trigger the relay and start the delay timer.  Now take the output of the second relay and run it to the lines which close the door.  When the timer goes off, it will trip the second relay, which will trigger the "close door" action.

I have oversimplified this description of course.  Protection diodes, power to the relays, a feedback so that when the door closes it turns off the latching relay and resets the time; all those details are left as an exercise for the reader.

I have this anxiety about timers.....I can see a case where one's car stalls and the roof/windshield etc. get badly mangled by a closing door.

Several places (even American Science and Supplus) sells sonar sensors for a fair price.   Why not wire it up to sense the car's presence (once the door is opened)  untill it loses "sight" of the car, and then closes it again.  It would work the same way in reverse.....it wouldn't "open' the door, but once opened, would keep the door open untill the car was inside....

.  Depending on your setup, it may or may not be easier to use door-opened and door-closed limit switches instead of the relays, diodes, &c that kelseymh mentions. Start the timer with the door-opened switch. The door-closed switch would lockout the timed part (in series with the timer contacts). If you ever need to leave the door open, you will need a manual lockout switch (in series with the door-closed limit switch and timer contacts).