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Old Jul 27, 2005, 08:02 PM
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ashdec87's Avatar
United States, MI, Detroit
Joined Feb 2004
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How to reverse a servo?

Hi

I"m putting together a Bob-E-Cat EDF and for the flaps to work right, one of the flap servos needs to be reversed. Because there are two servos i cant just use the reverse on the TX. One of the guys at work says i can jsut switch 2 of the servo wires (like reversing a brushed motor). Can i do that??

Or do i have to shell out for a reverse module thingy?

Thanks

ash
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Old Jul 27, 2005, 08:12 PM
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dgoslee's Avatar
Seaford, DE
Joined Jan 2002
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You need to reverse the wires on the motor AND reverse the outer wires on the feedback potentiometer (pot). If you don't reverse the pot, it will go to the end of the travel and jam and smoke.

Dan
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Old Jul 27, 2005, 08:35 PM
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Popsflyer's Avatar
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If the plane is already built, electronics installed and linkages hooked up. You can buy a servo reverser that plugs inline with that particular servo.
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Old Jul 27, 2005, 10:22 PM
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United States, MI, Detroit
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Ya everyhting is all hooked up.

I was jsut hoping i could do it without buying a reversing thing. Oh well, no biggie.

thanks

ash
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Old Jul 27, 2005, 11:04 PM
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emnm79's Avatar
Kennett Square, PA
Joined May 2005
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Hmm, I think you can do it to larger digital servos via a programmer, not sure though... I need to do the same for my funtana's elevator servos
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Old Jul 27, 2005, 11:47 PM
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ya you can, but i'm using an hs-85mg...not quite a programmable digi servo

ash
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Old Jul 28, 2005, 07:17 AM
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Andy W's Avatar
Marietta, GA
Joined Jun 1999
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What kind of Tx do you have? Most 6-channel and up support two flap servos.
..a
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Old Jul 28, 2005, 09:52 AM
Naturally altered
Joined Feb 2005
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Am i missing something? Now why do you need to reverse one of the servos? Possibly, there is physical limitation the way the plane is designed or built but....

With a Y adapter, two servos will work in unison if linkages are attached to the same side of the horn (both on the left side of the servo wheel, or both on the right), or opposite if linkages are attached to opposite sides of the servo wheel (typical aileron linkage for a single servo, or even two for that matter).

A computer radio should be able to handle two flap servos, either from built-in feature or by using a programmable mix.

If all the above fails, then you are left with the servo-reverser thingy option.
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Old Jul 29, 2005, 11:03 AM
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ashdec87's Avatar
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I"m using an Eclipse 7.

The way the servos are laid out, both flap servos face inward and both ail servos face outward. So the servos work in opposite directions. And sicne i'm using a y-cable i cant just reverse the direction of the servo through the TX.

Ash
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Old Jul 29, 2005, 01:31 PM
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Popsflyer's Avatar
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If you're using an Eclipse 7 and your receiver has enough channels, you can plug the servos into different channels and use one of the pre-set or custom mixes availible on the E-7. This will allow you individually program the normal direction the servo turns.

Otherwise break down and pay the $15 for a servo mixer.
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Old Jul 29, 2005, 01:37 PM
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Montag DP's Avatar
United States, GA, Atlanta
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Quote:
Originally Posted by ashdec87
I"m using an Eclipse 7.
The way the servos are laid out, both flap servos face inward and both ail servos face outward.
Ash
So you're using two flap servos and two aileron servos? Couldn't you just move the pushrod to the other side of one of the flap servo control arms, so that both flaps move in the same direction?

Sorry if I'm not understanding your setup correctly.
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Old Jul 29, 2005, 02:27 PM
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I use a Y-harness with a servo reverser built-in..
They are available.
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Old Jul 29, 2005, 03:00 PM
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Just hook up the pushrod to the other side of the servo arm. One side moves one way, while the other side moves the other way. Regardless of the orientation of the servo itself, what side it's connected on will determine which way the pushrod moves.

Of course if there is some kind of physical limitation (i.e. - you can't attach the pushrod to the other side because something is in the way, or the pushrod cannot be routed to that side, etc.), then you'd have to find an alternative method.
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Old Jul 29, 2005, 03:07 PM
RIP Ric
Andy W's Avatar
Marietta, GA
Joined Jun 1999
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I asked which Tx as the best answer is to use dual flap servo programming, if your Tx supports it - which it appears it does. That way, you don't have to reverse anything, and you get independant sub-trims, which you do not have with a mixer/reverser/y-harness setup.
..a
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Old Jul 29, 2005, 04:55 PM
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ok thanks for all of your input.

To answer one of the questions. It's got a sheeted wing, so i trimmed the servo arm so that one arm protrudes through the bottom of the wing.

I'll check the programming on the TX. Although i think the 2 flap servo option is only in glider mode. I guess if nothing else works, i can use the y adapter with the servo reverse. My only problem with that is the extension is LONG and my leads are already very long.

Thanks again

ash
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