I’ve decided using any solenoids to “push” a garage door remote button won’t work.
I started with using an old doorbell. Even a new one at Home Depot costs $10. The one I have actually has two long-stroke plungers in a dual solenoid package. Seemed like a perfect idea. The spacing between the plungers would have worked on the remote I was going to use. The remote would have had to been at a slight angle to the solenoids, but the spacing was nearly perfect.
The deciding factors to not go this route was several-fold. The doorbell transformer was 16Vac not 24Vac. I tried them with a 24Vac transformer and they would strike the doorbells (tampered to decrease the noise to a clunking sound) with even more force. I measured the current draw from the 24Vac transformer and recorded a sustained current of about 1A. Not a good thing. Second, the striking power was good and hard but the solenoid coil couldn’t provide sustained force on the buttons of the remote. It could punch hard but couldn’t sustain the button push long enough to operate the door. Plus, the solenoids 60Hz “humming” was enough to warrant some concern.
I think a relay configuration will be my best option. I’ve even thought about using the doorbell dual-solenoid to make home-grown relay connections. The current draw and humming makes that unlikely. I don’t want to risk a few bucks on a potential fire hazard.