Stopping the car aerial

[pieman54]

I've installed an electric aerial into my EL Futura (second hand from a fairmont) and am using 2 SPDT relays to reverse the motor (up/down). So with the radio off the antenna goes down and with the radio on the antenna goes up. I'm using the original car switch to do this (got one off ebay). However, when the aerial fully extends or retracts I have to hit the switch to cut power to the unit otherwise the motor keeps running (not nice!!). So the question is what should I use to automatically turn power off to the antenna at full height or when retracted????? This function is normally controlled by the high series BCM (Body Control Module) - my car has the mid series.

I've attached the circuit diagram (please excuse the quality!!!)

[pieman54]

Here's the circuit...........

[watchdog]

That cct is next to useless. I am only guessing here , but would imagine that it is driven by a stepper motor which is controlled by feeding it a set number of pulses to raise or lower it to its limits.

[Godzilla]

I have avoided posting because its been a while since i played with electric aerials.

I could have sworn ive seen electric aerials with a built in limit cutout and relay to stop the drive either way.

Edit; hang on what do you know.




It looks like red is permenent + with the ignition on, black -, and white is a signal from your radio turning on/off or a external switch.

The electric aerial should switch the drive motor on and off on its own via its limit switches and it should change direction via its own built in relay.
All it needs is a signal down the white wire via the radio or a switch.

It would be easier to install one of these 3 wire units rather than Fords 2 wire one with external control box.

[Godzilla]

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