Trim Wiring Question

[pvalovich]

-8A; two Infinity stick grips; Infinity relay card. I initially thought that I could wire both stick trim wires to a comon post (roll or pitch) on the relay card, and worst case, the first cockpit to activate either would rule. Then I awoke at 2 AM last night thinking about my assumption (Do other builders get these middle of the night RV inspirations / terror episodes?). For example, if the front C/P trims nose up, and while the nose up switch is activated, the rear C/P trims nose down, will the system: a) continue nose up; b) call a draw and shut down til the pilot's get their act together; or c) fight it out with simultaneous nose up / nose down power and burn up the motor?

Also, the relay card came with a couple micro switches that can somehow control trim access. Can anyone tell me how to wire them? Obviously the easiest solution is an either - or cockpit wiring scheme, but I thought I could eliminate the switches. Now I'm not sure.

[Rick6a]

I just completed adding and wiring a second Infinity grip for the rear seater. Its really very simple. Just wire all the functions you want the rear seater to have in parallel with the pilot's grip wiring. I used a terminal strip to help organize all those wires. The first picture gives you an idea of how I did it. The rear seat grip is handled a bit differently. The wire bundle for the grips contains four or five black ground wires. Separate and run the rear seat ground wires through the small switch J.D. sold you. Thus you can enable or disable the functions on the rear seat grip at your pleasure.

[647jc]

Rick,

Something to be considered or at least aware of when disabling the passenger grip buttons in this manner. The disable switch doesn?t completely disable the passenger grip buttons. Example: the pilot presses the left trim button (or any other button wired to his grips common ground); the passenger also presses or has pressed the same button on his grip. Now all buttons on the passengers grip are active (will do something when pressed) because the passengers grip ground is being sourced from the pilots pressed button. To truly isolate the passengers grip using a single switch, you need to include a simple signal or switching diode for each button signal on the passengers grip. This behavior may or may not be an issue for you but is something to be aware of.

[PaigeHoffart]

I'm not familiar with the particular relay board that you're talking about, but if it's wired like http://www.infinityaerospace.com/trim2.pdf, when opposite trim inputs are applied, both nose-up and nose-down relays will engage, giving you no net voltage at the motor (both motor leads will be at 12V). No smoke, no worries.

It's also nice because if you have a run-away trim condition due to a stuck relay or shorted wire, trimming opposite direction will cutout the motor.

Paige
RV-8A