foward/reverse motor

i want to hook up a motor so when i turn the key on it will go in one direction and when i turn the key off it will go in the other.  basically reversing the polarity so it goes in a different direction when the ignition is either on or off.  the motor has just 2 wires, pos and neg.  when it gets power one way the motor will go forward and when the polarity is reversed the motor will go backwards.  but i need power to be cut when its moved into its position.  in other words i dont want it to still have power the whole time the ignition is either on or off.  thanks for any help.

Here is a circuit I designed for my amp rack but you can adapt it for your needs or at least give you an idea of what you need.

Relays 1 and 2 do the reversing while relays 3 and 4 cut the power when they've received signals from the limit switches. Relay 5 is a safety interlock which assures that the motor will not work while the trunk is closed. The 6 second timer and motor shown near the top left are used to unlatch the amp rack - just ignore it for simplicity sake.

I used a DEI 450R channel expander which has timed outputs to open and close which sends a continuous signal maxed to 60 seconds to relays 1 and 2 - obviously the limit switches stop the motor when the limit has been reached even if the 450R hasn't timed out. You may substitute the 450R with your ignition on/off signals.

A second alternative would be a DEI 529T which can control one motor in two directions and has a built-in current limit control. You still need to provide the required "ignition" control signals via relays.

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Prepare your future. It wasn't the lack of stones that killed the stone age.

Here is My design.

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

Or you can just use a switch Double Pole Double Poll.

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

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John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !

John, I liked all your ideas especially the simplicity thereof. I try to adhere to the KISS philosophy (Keep It Simple Sam) as much as possible. The first idea wouldn't work for me because I don't want the rack to move the instant I open the trunk but rather when I ask for it via remote control and I use a latching relay built into the 450R to enable/disable power in the circuit - however your design allows to interupt movement and change direction at any time . . . nice!

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Prepare your future. It wasn't the lack of stones that killed the stone age.