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Jul 27, 2005, 07:02 PM
Registered User
ashdec87's Avatar

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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Jul 27, 2005, 07:12 PM
Registered User
dgoslee's Avatar
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
Jul 27, 2005, 07:35 PM
Oldie but goodie
Popsflyer's Avatar
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.
Jul 27, 2005, 09:22 PM
Registered User
ashdec87's Avatar
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
Jul 27, 2005, 10:04 PM
Yakkin' it up!
emnm79's Avatar
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
Jul 27, 2005, 10:47 PM
Registered User
ashdec87's Avatar
ya you can, but i'm using an hs-85mg...not quite a programmable digi servo

ash
Jul 28, 2005, 06:17 AM
Registered User
Andy W's Avatar
What kind of Tx do you have? Most 6-channel and up support two flap servos.
..a
Jul 28, 2005, 08:52 AM
Naturally altered
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.
Jul 29, 2005, 10:03 AM
Registered User
ashdec87's Avatar
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
Jul 29, 2005, 12:31 PM
Oldie but goodie
Popsflyer's Avatar
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.
Jul 29, 2005, 12:37 PM
Sink stinks
Montag DP's Avatar
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.
Jul 29, 2005, 01:27 PM
Ascended Master
Sparky Paul's Avatar
I use a Y-harness with a servo reverser built-in..
They are available.
Jul 29, 2005, 02:00 PM
Registered User
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.
Jul 29, 2005, 02:07 PM
Registered User
Andy W's Avatar
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
Jul 29, 2005, 03:55 PM
Registered User
ashdec87's Avatar
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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