Garage door opener

I was reading on Directed's forums today about a guy who used an extra alarm module to control his shops garage door opener. Our shop has a very old opener that does not have a remote control capable brain.

I am wondering how hard it would be to use an older keyless entry system say even a modern Auto Mate 4104a and have it setup that pressing unlock would open the garage door and pressing lock would close the door.

The switch on the wall is a 3 button OPEN/STOP/CLOSE momentary switch setup. Using 24v and simple momentary contact to operate the functions.

I would have a 12v battery maintainer plugged in and mounted near the opener switch, which would provide 12v power (and ground) to the 4104. I would only be using the 4104 to operate relays to make the contact for the opener switches.

My first question is will a standard 5 pin 30/40a 12v relay be able to handle the 24v momentary voltage of the opener switch, and if not would a 24v specific relay be able to be controlled by a 12v keyless entry system?

To master and control electricity is perfection. *evil laugh*

Within reason the voltage on the switch side doesn't matter, only the coil. Most 12V automotive relays work in the range 7.5 to 18 volts in practise. Thus as long as the 30/40 (you can also get 40/40) will handle the motor current you're OK, 30 amps at 12 volts = about 18-20 amps at 24 volts. In Europe most trucks over 3 tons use 24 volt electrical systems with droppers for the radio so yes I've used this trick many times with a 12Volt alarm.

Well since the buttons i plan to operate are momentary meaning press and release and the door continues until fully open/closed i dont think the relay would see anything other than a brief 24v signal across 30 and 87 when activated. If thats true then the 30/40 relay should be fine.To master and control electricity is perfection. *evil laugh*

Yes, no problem there what about the door's current draw.

Howie, from racerjames76's description, the door motor's current draw is not through the 3 button wall switch and will not be through the relays he intends to add. the12volt • Support the12volt.com

Point taken! Thanks. It's my age, cogitative disassociation!

I've done what you describing quite a few times. Works great.If i Can't Install it    I Don't need it   Joe