Pitch Trim Control

[VictorV]

Bear with me while I attempt to explain what I'm trying to do :)

My goal is to be able to use both the KF-supplied pitch trim switch and buttons on the control stick.

I'm using the Ray Allen G405 stick grip. When a button is depressed, the output wire is connected to ground.

My avionics are Garmin and I'm using the GSA-28 servo. The trim switch is connected to the pitch servo which
passes the signal along to the TCW Safety Trim Booster which then controls the pitch trim actuator. The safety
trim booster is needed since we need to drive the trim actuator with more current than the stick grip can
handle.

Here's where it gets complicated. The pitch servo expect 2 signals A and B. To move the trim in one direction
you put 12v on A and Gnd on B. To move the trim in other direction you just reverse the polarity and A is Gnd
and B is 12v. This is what the KF-provided switch along with their wiring diagram provides.

The question is how do you connect the stick grip buttons and the KF-provided switch together to generate the polarity-reversing
signals? I was thinking maybe an H-Bridge might work.

Here's the wiring diagram provided by TCW:
32330

Victor

[alexM]

I could fill volumes with everything I don't know about electrical wiring, but I have this diagram built into my schematic
https://www.tcwtech.com/wp-content/uploads/2020/04/Safety-Trim-Application-Note-Using-Ray-Allen-RS-2-Rocker-Switch-with-Additional-Hat-Switches.pdf
That covers the rocker plus stick grip switches. I don't have an auto pilot so it may get complicated to make that work.

[VictorV]

Thanks Alex. That's good info. I also found this: http://www.rayallencompany.com/products/accessories.html which looks like it does the right thing.
I wonder how this works along with the Garmin servo....

V.

[Geek]

Or you could just buy a couple good relays and wire this in. I'm using the VPX which does this for me but literally this is all it takes.

32335

[Flying Pig]

That's a lovely wiring diagram @Geek. I see it has references to other pages as well. What did you use to draft it?

[MikeFairbanks]

It's in the G3X Touch installation manual.