I have a Ray Allen G205 grip which I'd like to use on the pilot side to control the trim in addition to the panel switch. I can wire up the buttons in the grip OK, and I know where to run the PTT and ground wires, but the rest is a mystery. If anyone has wired up stick trim buttons in an RV-12, I'd appreciate some advice. On the other hand, if it's too difficult I'll just use a G101 with the PTT button.
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RV-12 trim on the stick?
- Thread starter rgmwa
- Start date
Bill_H
Well Known Member
If it was me, I would run the trim switch wires up into the panel base. From there it is easy enough to figure out, when you install all the avionics, which wires are coming from the trim switch on the panel, and connect them up in parallel. (It would basically be the same wiring connectivity as if you had trim switches on each stick, does the Ray Allen documentation show the hookup?)
It is also easy to identify the wires that come to the panel from the trim motor so a few minutes with a voltmeter (and the new wiring diagrams) should tell/confirm the tale. Depending on your risk level, you could leave those wires (from the grip) disconnected until after inspection. You are responsible for selecting the grip anyway.
It is also easy to identify the wires that come to the panel from the trim motor so a few minutes with a voltmeter (and the new wiring diagrams) should tell/confirm the tale. Depending on your risk level, you could leave those wires (from the grip) disconnected until after inspection. You are responsible for selecting the grip anyway.
Thanks Bill,
I was thinking along those lines but wasn't sure how others may have done it. The Ray Allen documentation doesn't give a lot of guidance beyond the wiring of the buttons (not surprising). I'm building EAB, so the legalities of this modification wouldn't be an issue.
I was thinking along those lines but wasn't sure how others may have done it. The Ray Allen documentation doesn't give a lot of guidance beyond the wiring of the buttons (not surprising). I'm building EAB, so the legalities of this modification wouldn't be an issue.
Bob, this is not meant in any way to slight Bill, but I would suggest that you also talk to Joe Gores about this. He will probably respond anyway, but he is the unofficial/official electrical guru on the 12. I will admit that Bill's advice makes perfect sense. Let's see what Joe says.
Bill_H
Well Known Member
DITTO DITTO DITTO - I still consider myself a newbie, inexperienced 1st-time builder compared to the seasoned vets on this forum!
Note also that if you are going Skyview, you will likely get the conversion harness that adapts to the new connector box, with its probably-different-pinouts compared to the original harness.
Also - RGMWA - I will be in Perth arriving June 21 afternoon, working all day June 22, but not that evening, departing early June 23. Staying downtown, probably will not have a car though. Suggestions on food? See your build if you are close?
Note also that if you are going Skyview, you will likely get the conversion harness that adapts to the new connector box, with its probably-different-pinouts compared to the original harness.
Also - RGMWA - I will be in Perth arriving June 21 afternoon, working all day June 22, but not that evening, departing early June 23. Staying downtown, probably will not have a car though. Suggestions on food? See your build if you are close?
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Control Stick Elevator Trim Switch
Here is an excerpt of the trim circuit schematic:
https://docs.google.com/open?id=0B7ZTG2VpCuDRT2kzQVRMUU9yVVk
I can not say how to connect the control stick switches without knowing more about them. But running the wires to the control panel is a good idea. If someone can send me a link to the control stick switch wiring diagram, it will be helpful. We must be very careful so that any wiring mistake or hardware failure does not result in a runaway trim situation. Depending on the control stick wiring, it might be necessary to use a relay.
Joe Gores
Here is an excerpt of the trim circuit schematic:
https://docs.google.com/open?id=0B7ZTG2VpCuDRT2kzQVRMUU9yVVk
I can not say how to connect the control stick switches without knowing more about them. But running the wires to the control panel is a good idea. If someone can send me a link to the control stick switch wiring diagram, it will be helpful. We must be very careful so that any wiring mistake or hardware failure does not result in a runaway trim situation. Depending on the control stick wiring, it might be necessary to use a relay.
Joe Gores
MacPara
Well Known Member
My only concern with this mod would be how to get the additional wires through the stick. I had such a hard time to just get the PTT routed through it that I doubt I could add anything. Running the wire on the outside would be an option but sure would look ugly.
Figuring out which wires would have to get splices should be pretty simple. I would probably chose to connect them in parallel to the original trim switch, so I'd be looking at the wires coming from the switch and fuse panel. They are all white wires which means you'd have to open up the backshell and see to which pins they connect to determine the correct wires.
If you want me to determine which pins you'd have to connect to, let me know.
Figuring out which wires would have to get splices should be pretty simple. I would probably chose to connect them in parallel to the original trim switch, so I'd be looking at the wires coming from the switch and fuse panel. They are all white wires which means you'd have to open up the backshell and see to which pins they connect to determine the correct wires.
If you want me to determine which pins you'd have to connect to, let me know.
Joe,
Here's a link to the G205 instructions (Wiring Style 1 on page 4). The 4 top buttons are intended for Up/Down/L/R trim, so there are normally 7 exit wires (including the PTT wires), however we only need 5. I was planning to connect the DN/L and UP/R buttons so either pair would activate the trim.
http://www.rayallencompany.com/RACmedia/instructionsG2grip.pdf
The wire supplied with the switch is 26 gauge so it's quite fine, but it will still be a challenge to get them all down the stick. I would need to order more to be able to run the wires all the way to the panel without splicing.
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I deleted part of this posting because it referred to the old RV-12 control board, not the newest one.
The trim servo can not be powered with steady 12 volts because it will run too fast. The existing circuit puts out a pulsing DC that gives the servo motor full torque without over speeding.
The Ray Allen switches could be used, but doing so will not be as easy as connecting a few wires. It will turn out to be a bigger project than expected and will require some electrical knowledge.
Joe Gores
The trim servo can not be powered with steady 12 volts because it will run too fast. The existing circuit puts out a pulsing DC that gives the servo motor full torque without over speeding.
The Ray Allen switches could be used, but doing so will not be as easy as connecting a few wires. It will turn out to be a bigger project than expected and will require some electrical knowledge.
Joe Gores
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MacPara
Well Known Member
Why do you want to control the servo directly? My suggestion was to just add wiring to the switches in the grip so they would act (and do) just what the trim switch in the panel is doing.
I had a chance to look at the electrical diagram of the -12 again yesterday. It appears that the trim switch is providing the PTRIM + and PTRIM- wires with whatever comes from the mystic triangle symbol in the plans. I assume this is +12V or ground, I'd have to measure that to see what it is as I am unfamiliar with that triangle symbol.
However, if the PTRIM+ and - wires get spliced and the triangle voltage is also sent to the stick, the Ray Allen switches should be wired to do the same thing what the panel trim switch is doing. Allt his would do is to add an additional trim switch (or switches if you want the right seat to have the same) to the wiring. The magic of modulating the pulse width to actually control the servo would still be done by the Control Module. No need to reinvent that or did I not understand the initial question?
I think this could be done by adding 3 wires to the stick and splicing them into the harness that connects the switch module and the Control Module.
I had a chance to look at the electrical diagram of the -12 again yesterday. It appears that the trim switch is providing the PTRIM + and PTRIM- wires with whatever comes from the mystic triangle symbol in the plans. I assume this is +12V or ground, I'd have to measure that to see what it is as I am unfamiliar with that triangle symbol.
However, if the PTRIM+ and - wires get spliced and the triangle voltage is also sent to the stick, the Ray Allen switches should be wired to do the same thing what the panel trim switch is doing. Allt his would do is to add an additional trim switch (or switches if you want the right seat to have the same) to the wiring. The magic of modulating the pulse width to actually control the servo would still be done by the Control Module. No need to reinvent that or did I not understand the initial question?
I think this could be done by adding 3 wires to the stick and splicing them into the harness that connects the switch module and the Control Module.
Adding an additional switch (or switches) would work, but as always, their is a potential for other issues that initially may not be obvious.
If a trim switch was being activated and another person in the airplane inadvertently activated a different trim switch for pitch trim in the opposite direction (bumped teh switch on top of their stick), there would be no circuitry in place to prevent the trim system from being shorted out.
My posting above on 6-11-2012 referred to the original RV-12 control board with Dynon D-180 where the input to the trim switch is not easily accessible. I am not familiar with the new SkyView avionics package and control board and trim switch. If it is possible to easily tap into the input of the trim switch on the new control panel, then I take back what I said about the project being difficult.
Here is a link to a schematic using one Ray Allen stick grip:
https://docs.google.com/open?id=0B7ZTG2VpCuDRVXpzclNkWXRZN3M
Here is a link to a schematic using two Ray Allen stick grips:
https://docs.google.com/open?id=0B7ZTG2VpCuDReTZUSmN4bFhuVkk
Joe Gores
Here is a link to a schematic using one Ray Allen stick grip:
https://docs.google.com/open?id=0B7ZTG2VpCuDRVXpzclNkWXRZN3M
Here is a link to a schematic using two Ray Allen stick grips:
https://docs.google.com/open?id=0B7ZTG2VpCuDReTZUSmN4bFhuVkk
Joe Gores
MacPara
Well Known Member
I see, Joe. Well, the trim switch in the new switch panel might still be a bit hard to get at (I didn't really look into that), but due to the harness carrying the necessary wires you would have to tweak and the harness being easy to get at, one could do that mod in the SV system pretty easily. However, the problem with the activation of both trim directions at the same time does exist and I would therefore not really think about a right stick mod with some precautions (which would make this project a lot mroe complicated). Doing this on the left side only and maybe even disabling the panel trim switch would be an option though.
It's a pity we don't know what would happen inside the Control Module if PTRIM + and - would get activated at the same time. There is a chance that this case would be caught in the electronics already. I am not brave enough at this point to try it though
The CM is priced at $525 plus shipping and I don't want to burn it up before it even took off yet.
It's a pity we don't know what would happen inside the Control Module if PTRIM + and - would get activated at the same time. There is a chance that this case would be caught in the electronics already. I am not brave enough at this point to try it though
The CM is priced at $525 plus shipping and I don't want to burn it up before it even took off yet.Note that trim on the dash is toggle type so you can never activate up and down simultaneous.
When you parallel the Ray Allen pushbuttons however you can, causing a short.
I put two small relays in the circuit which interlock eachother.
Works great.
I also put the autopilot pushbutton and fuel pump on the stick.
Very very intense job to get So many wires in the stick
When you parallel the Ray Allen pushbuttons however you can, causing a short.
I put two small relays in the circuit which interlock eachother.
Works great.
I also put the autopilot pushbutton and fuel pump on the stick.
Very very intense job to get So many wires in the stick
That was my intention in the original post. It seemed easy in principle, but I'm out of my depth when it comes to electronics. Jack has taken it a step further with A/P, fuel pump and relays, but for now at least I'm keeping it simple and just using the PTT trigger switch on the G205. My arms are long enough to reach the panel, and in the meantime those extra buttons on the stick look very cool. I might add some useful new stickers like `coffee', `beer', `reading lamp' and `flight attendant'
There is NO possibility of any combination of switch operations that can cause a short circuit if wired according to this schematic. The panel mounted pilot-copilot selector-switch only allows one set of switches to be connected at a time. The output of the original RV-12 trim switch has been disconnected and is not a factor.
The switch would normally be in the pilot (left) position. The copilot grip switches would not work unless the panel mounted switch is moved to the right side. In case of trim runaway, the new panel mounted selector switch can be moved to the center "OFF" position.
Joe Gores
Many things are possible once you have a G205, Bill. Thanks for the suggestions.
Seriously, I appreciate all the technical discussions too. Very interesting.
Cheers
Rob
