Automotive power antenna wiring

Thread Starter


Joined Sep 8, 2018
Hi all, I've recently decided to swap the power antenna in my car, the old one is one of those cheap Chinese ones you see on ebay and the tolerances are so poor the different layers sit limp to each other when it's up and also let in road dirt between them, it is now showing signs of giving up after only 2+ years. A while back a friend gave me a high quality Japanese power antenna made sometime in the 70s which I will be replacing it with.

A problem is the Chinese antenna has a mechanical automatic motor stop for when the antenna has finished going up or down and a reversing relay as it is designed for radios that send a constant 12v to it when they're on like the radio I have. This Japanese antenna is designed to use what is basically an electric window switch and therefore comes with the wires going straight to the motor with no reversing relay or automatic stop mechanism but will however safely ratchet at the end of its travel until the switch is released.

Adding a reversing relay will be no problem for me at all but I am having trouble designing a circuit that will automatically stop the motor after, say 5 seconds. I'm looking for a circuit that can detect the 'activator' wire from the radio changing in state from either off-on or on-off and then activating a relay solenoid for 5 or so seconds. Any help would be greatly appreciated


Joined Jan 30, 2016
Do you know the operating current for the motor? Does it ratchet at the end or just stall? Can you detect a current change at the ends of travel? A timer is easy enough but current sensing is neater!

For the timer I'd use the ubiquitous NE556 (dual 555), 1 half to handle the up/down trigger and the second half to do a 5 - 10sec timer.