My garage door opener has a small light which turns on when the door is activated and turns off after about one minute. It provides enough light and enough time to get out of the car and into the house. I leave home for work before sunrise and I like more light than the garage door opener gives off buy itself.
I thought it would be good if the garage door opener could switch on the main garage light and stay on for longer. Time to hack the garage door opener…
I removed the globe from the opener and check the voltage that drives it. 12V AC. Next is how to control the main garage light?
I want the light to come on when the main switch is turned or if the garage opener light. Two switches will be used in parallel so that the light will stay on whenever either of the switches is on. The existing light switch will be used as the first switch and a relay will be used as the second switch.
Although I could use a 12V AC relay I decided to use a DC relay driven via a bridge rectifier so that I could extend the “on” time for the light. The one time is extended using a capacitor. The capacitor is charged by the supply voltage coming out of the bridge rectifier. When the supply voltage is off the capacitor discharges into the relay coil. The relay opens when the capacitor no longer has enough charge to hold it closed. The capacitor has been chosen to keep the relay closed for around five minutes.
Although this is a very low-tech solution to my garage lighting problem. I am very happy with and it has been working for over 5 years without any problems.