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mattsmith

Well Known Member
Hi, I'm installing an infinity grip in my RV-8 and want to know if I can run the power leads, from the pitch trim servo and the roll servo to the cooly hat on the grip or do I need a relay between the grip and the servo? If I need the relay where is the best place, under the floor pan or behind the panel? Trim indicators will be ran to a dynon skyview. Thanks for the feedback.
 
mattsmith said:
Hi, I'm installing an infinity grip in my RV-8 and want to know if I can run the power leads, from the pitch trim servo and the roll servo to the cooly hat on the grip or do I need a relay between the grip and the servo? If I need the relay where is the best place, under the floor pan or behind the panel? Trim indicators will be ran to a dynon skyview. Thanks for the feedback.
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Electric trim used with the Infinity grip means you are going to need relays. Where you mount those relays is entirely up to you. For the pitch trim relay, I suggest you install the MK-111 combination relay/speed controller. It has a pot that allows you to adjust sensitivity of the pitch trim. Some builders never installed the speed controller then go on to bemoan electric trim as being too sensitive.

As I did with the Infinity cable and flap relay deck used to manipulate the flaps via the Infinity grip, I mounted the components behind a hinged console so I can access them fairly easy as required:

2wc31fs.jpg


Upon reflection, I now think it may (or may not) be more practical to mount the relays somewhere on the (builder option) baggage bulkhead door for even easier access:

6yzcsh.jpg
 
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Trim Relays-Safety Trim

Another option is the Safety Trim system by TCW (sold by Steinair and advertised on this site). The system has a single module and a simple wiring diagram for single or dual stick grips. Options for single or dual axis Ray Allen T2/T3 servos as well as an airspeed switch to provide a two-speed trim option to cut trim speed while in cruise and leave it normal/fast under a pre-set speed. For more info see:

www.steinair.com or
www.tcwtech.com

I bought mine here during a group buy...haven't flown with it yet, but installation was simple.

Good luck,
Mike
 
Really?

I just started wiring, but I wasn't planning on using relays for my pitch trim. The MAC trim is really low amperage. Has anyone else ran their's direct to cooly hat?
 
I ran mine without a extra relay, thru the c1a area on the circuit board. I guess i thought that the 3 relays on the board were for this purpose. It runs the trim up and down, but I am not flying yet. I suppose my wings will fall off now that I know this.
 
MATT,

I used the safety trim and infinity grips in my 8 not flying yet but trim servos work there is some pictures on my kitlog web site where I mounted the controller and put the on off switch also where I put terminal block hope this will helps
 
panhandler1956 said:
I just started wiring, but I wasn't planning on using relays for my pitch trim. The MAC trim is really low amperage. Has anyone else ran their's direct to cooly hat?
Click to expand...


Brent,

No relay for the pitch trim? To avoid unnecessary surprises later, you may want to review the grip's technical specifications, including the recommended use of relays as described on this page of the Infinity website:

http://www.infinityaerospace.com/infgrip.htm
 
O.K. Just so I am clear, I need to run the roll servo to a relay and if I run the pitch servo to a relay/speed controller MK-111 that will work or am I missing something?




No relay for the pitch trim? To avoid unnecessary surprises later, you may want to review the grip's technical specifications, including the recommended use of relays as described on this page of the Infinity website:
 
It says the that the 4 way switch is rated at 1 amp at 12 volts.

Not arguing, but how many amps can you put thru a 20' run of 26 gauge wire, like the ray allen people use for wiring the trim? My Aero-elec book doesn't go that small, in fact he says to use 22 or larger for strength and simplicity.

How many amps does the trim motor draw? I just assumed that if RA was selling the wire bundle for the trim motor, it was up to the task.

Good discussion, I am glad I haven't riveted the floor in yet.
 
lancef53 said:
It says the that the 4 way switch is rated at 1 amp at 12 volts.

Not arguing, but how many amps can you put thru a 20' run of 26 gauge wire, like the ray allen people use for wiring the trim? My Aero-elec book doesn't go that small, in fact he says to use 22 or larger for strength and simplicity.

How many amps does the trim motor draw? I just assumed that if RA was selling the wire bundle for the trim motor, it was up to the task.

Good discussion, I am glad I haven't riveted the floor in yet.
Click to expand...

The problem is not just one of "load" - I don't think that you can actually make the servo work properly without a relay, because you need to reverse the polarity of the "drive" wires at the servo to make it run in either direction. The coolie hat switch simply provides continuity from the center pole to the appropriate "edge" pole (it has one center and four edge conductors), and I don't know how you'd wire that to make it work - but then, I am simply an aeronautical engineer, and not one of those smart EE's....:p
 
lancef53 said:
......I just assumed that if RA was selling the wire bundle for the trim motor, it was up to the task.....
Click to expand...
If you use the RA momentary rocker switch that is included with each servo kit as shown below, then no additional relay is required. If however, you elect to use a different switch such as the Infinity grip sports, that switch may or may not be acceptable, hence, a relay is required for each axis of trim. Infinity includes several wiring schematics and suggested relay options on its website.

2lxdl6d.jpg
 
Paul, it works just fine wired to just the 4 way switch, as far as I can tell. I can run the trim all the way each way, I wired it just like the flap--reverse the polarity to reverse the motor.

Rick, I know that there is SEVERAL wiring diagrams on the infinity site--I think that is where I am getting confused. It has wiring diagrams for about everything, from the relays to no relays, and everything in between.

Like I said before, I didn't think much of it because of the wire size in the RA wire bundle. It doesn't take much of a switch to match the capacity of a 26 ga wire at 12 volts.

On the wrecked 8A that I bought to use for parts, the flap motor was wired directly to the circuit #3 area of the trim relay buffer board(and the left toggle on the stick). It worked fine on the plane for 192 hours until it ran out of gas, so I assumed that it was ok to wire it that way again. The trim relay board has 3 circuits like this, so I just used circuit #2 for the trim motor. I assumed that the trim motor used less power than the flap motor.

http://www.infinityaerospace.com/Relay_Deck_Wiring_Schematic.jpg

Thanks for the help, sorry for dragging this thread off into my direction.

Edit--I was looking at some Ray allen info that came with the speed control and wiring that I bought, and it mentions that the no load current of the servo is 150 MA. It also mentions that the REL-2 relay deck that they sell to use with the servos has a maximum rating of 1 amp. With this in mind, is there an advantage to using a Ray Allen relay, if it is rated at the same 1 amp as the Infinity china hat switch?

I am getting confused
 
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OK, so just so I understand Lancef53, you are wired from the switch through a speed controller? That would make sense, as the controller would have something in it to make it work. I just can't figure how the coolie hat alone, wired directly to the two trim motor wires would work.
 
No, just wired to the coolie hat switch thru the circuit #2 like in the link I posted. The trim up and trim down wires from the 4 way switch are connected to the right side of the board C2A and C2B terminals, and the servo is connected to the C2A and C2B on the bottom. I have the speed controller in hand, but not in the system yet. (I forgot to install it when I was wiring, I will install it when I pull the floor out again in a couple of days)

Sorry for the confusion--Have you ever heard the saying "you meant what I knew"
 
lancef53 said:
No, just wired to the coolie hat switch thru the circuit #2 like in the link I posted. The trim up and trim down wires from the 4 way switch are connected to the right side of the board C2A and C2B terminals, and the servo is connected to the C2A and C2B on the bottom. I have the speed controller in hand, but not in the system yet. (I forgot to install it when I was wiring, I will install it when I pull the floor out again in a couple of days)

Sorry for the confusion--Have you ever heard the saying "you meant what I knew"
Click to expand...

OK, so you ARE going through the relay board, and that makes total sense. You certainly don't need separate relays in that case!

Paul
 
Isn't the relay board part of the grip?

Sorry about that Paul, I didn't realize that the original poster had used up all of the relays on the relay board. If I had known that, I wouldn't have jumped into this.

Rick, what are you using your relay board for that you need to add relays?

I got my grip from the wrecked plane that I bought, with no info on it. I got all of my info from the Infinity site, and assumed that the relay board was a standard part of the grip.

Sorry for talking in circles:eek:
 
Ironflight said:
The problem is not just one of "load" - I don't think that you can actually make the servo work properly without a relay, because you need to reverse the polarity of the "drive" wires at the servo to make it run in either direction. The coolie hat switch simply provides continuity from the center pole to the appropriate "edge" pole (it has one center and four edge conductors), and I don't know how you'd wire that to make it work - but then, I am simply an aeronautical engineer, and not one of those smart EE's....:p
Click to expand...

That reverse polarity was what I was missing- forgot about that. Thanks guys! - off to get a relay I go.
 
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So if I wirer the roll servo to MSTS-SRD and the pitch servo to MK-111 it should work rite. Or do I need a speed controller for the roll servo also?



Edit- just ordered the all in one relay board from infinity, thanks for the help.
 
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