Technical How to wire something like a power antenna?

K.I.S.S.!

 

I don't know where you are getting your information from but using a DPDT relay has the same possibility of producing a short as 2 SPDT relays. Yet Neither are a fatal flaw to the relays or the the relay system itself. The only thing that can happen is the accessory stays on (like the wiper motor stays on) or stops at its limiters (like the linear actuator has internal limits and will auto stop).

• No Positive or Negative direct power for the motor will only cause the motor to move in one direction
• No Positive or Negative tigger power to either relay will only cause the motor to move in one direction
  
• Welded/stuck contacts in either relay will only cause the motor to move in one direction

The only reason to use a DPDT relay instead of 2 SPDT relays is for the convenience of doing less wiring. However the benefit of using 2 SPDT relays is that you can get them at any auto parts store. You can get a DPDT relay there too but you have to have a specific part number, that they may not even carry. They don't just have them in the general electrical section.

 

I like that idea too.

 

While that sounds like a good idea it also SOUNDS like a bad idea. Key word is SOUND. I would not like it uncontrollably fast open and fast shutting, and the sound it will make. If you have auto door locks you know the just the sound of them actuating now add the sound of the winter grille slamming shut. Yes you can add add bumpers but why add more. Best to use a slow moving controlled linear actuator.

 

My 55 IH had a handle to pop up a cowl vent for the interior. I think I would like a mechanical set up.