elevator trim switch

I'd like to install Van's micro toggle switch on the control stick for elevator trim. It's (on)-off-(on) but is only single pole, so it has just 3 contacts in back. Trying to figure out how to connect the 2 white wires coming from the trim servo. Do I need an intermediate relay? I can't find a DPDT (on)-off-(on) micro switch online... Has anyone done this?

A simple relay is what you need if you are not using one of the various trim systems (Safety Trim, Dynon AP panel, Garmin's version, etc.).

The relay is used to reverse the two white wires:
- relay off A goes to A, B goes to B, and you trim up
- relay on A goes to B, B goes to A and you trim down

If the switch you select does not have the current rating needed for the trim servos (some top hat switches are limited) then you use two relays, one for trim up and one for trim down. The trim switch provides ground to the relay you want to turn on for the desired trim action.

You don't want to use a massive relay. Some like this works:
Tab mount: http://www.alliedelec.com/te-connectivity-k10p-11dt5-12/70198592/
Socket mount:http://www.alliedelec.com/omron-automation-my2-dc12-s-/70178954/

For what it is worth, Safety Trim is a good product and it makes all this very simple.

Carl

I second that on Safety-Trim. It vastly simplifies the wiring and has some other good features with it also.

If you are using the Dynon and AP setup, a simple grounding switch, like in the Infinity grips is all you need, and the Dynon will auto trim while in AP mode.