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Two elevator servos?

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Tim Kearsley03/04/2008 22:10:00
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Hi all,

Apologies for asking a question to which I ought to know the answer!  I'm building a model which has two servos for the elevator - one driving each half.  How do you connect these to the receiver?  Is it a "Y" lead or do you put one on the elevator channel and one on an auxiliary channel and do some mixing in the Tx?

Many thanks,

Tim.

Andy Green03/04/2008 22:14:00
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I only have 1 model with 2 elevator servos, and I use 2 channels, however I do have the luxury of a radio that supports this.

Details on how to set this up on JR can be found here on there JR's website

http://www.jrradios.com/Articles/Article.aspx?ArticleID=1457

Andy

Nick Cooper03/04/2008 22:26:00
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22 forum posts

also have a model with twin elevator servo's. have used a "Y" lead with no problems.

ATB

Nick

Tom Ruut03/04/2008 22:27:00
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50 forum posts
 A Y lead is the way to go!
Tim Kearsley03/04/2008 22:47:00
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Thanks guys.  That was a VERY quick response!!  Andy, I'm using a Spektrum DX7 Tx, so have 7 channels to play with in total.  It sounds though like a "Y" lead should do it.  I should add that the model is a Seagull Edge 540 EP.  It uses 5 servos in total (2 for ailerons, rudder and 2 for elevator).

Thanks again.

Tim.

Tim Kearsley04/04/2008 11:03:00
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Having thought this through a bit further, is a "Y" lead definitely going to be OK?  Presumably a "Y" lead drives both servos in the SAME direction (e.g. both clockwise).  If that's the case then I will have one elevator half going up while the other goes down (the servos are on opposite sides of the fuselage of course, so C/W for one will drive the elevator up and C/W on the other side will drive the elevator down).

Am I right in my thinking here?  I have to admit that I am getting ever so slightly confused now!

Cheers,

Tim.

Tim Kearsley04/04/2008 11:16:00
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I think I've answered my own question now.  I use Spektrum radio and there's a very nice article here which explains how to set up dual elevator servos from the Tx.

Cheers,

Tim.

Bob Cotsford04/04/2008 12:42:00
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so with a y-lead, why not run both connectors to the left hand arm on the servo, for example?  Or if they out in the open on the fuselage side, top servo arm on one side, bottom on the the other, that should work shouldn't it?
Andy Green04/04/2008 13:31:00
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Tim, Google knows everything, you just have to know what to ask

Andy

Tim Kearsley04/04/2008 13:39:00
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Bob, you're absolutely right.  Also, I see you can buy "active" "Y" leads, which will reverse one servo if you want.  Seems like there are numerous solutions!

Andy, yes I know.  Filtering the good from the bad is the key.....

Tim.

Aussie Bob06/04/2008 23:26:00
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 Can you get handed  [paired] servos?
Bill Brownlie10/04/2008 12:56:00
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7 photos
I have just finished a seagull extra 540 and used a futaba reversing y lead for the elevator, it keeps the linkage to the two halfs exactly the same measurements. Ones a mirror image of the other and works great. The electronics on the y lead also has a Pot to give you trim on one servo so you can match the two halfs up otherwise the trim on the Tx will move both
Tim Kearsley10/04/2008 13:04:00
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That's interesting Bill.  Is your model the Edge 540 electric powered one?

I've adopted a different approach to you for the elevators and have done it by using the AUX2 channel on the Spektrum DX7 for the left elevator, the normal elevator channel for the right elevator and mixed the channels 100% in the radio.  This method also allows you to tweak both sides so that they track perfectly.

If you've built the EP Edge 540 I'd be interested to know how you get on with it.

Cheers,

Tim.

Tim Mackey10/04/2008 13:15:00
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Therefore making use of that little known Spekky feature "servo synch"

Heres a summary of how to do it with the DX7 - courtesy of Bob Pastorello AMA.

The TX can do dual elevators easily. However The ONLY 2 x mixes that "master" the trim into BOTH channels are Mix 5 and 6 so use one of them. Doing dual elevators, the "elevator" Travel adjust sets BOTH as soon as the mixing is turned ON, the 2nd channel (AUX2) travel adjust will have NO effect. It's supposed to work that way.

Both channel "sub trims" DO work, and may be used to fine tune centres, if you cannot do it mechanically.

If you cannot get identical travel mechanically after Mixing is setup, set the OVERALL deflection using the "Elevator" Travel (ATV)

Adjust the "MIX Volume" (% in the Mix function) to alter the SECOND channel, either less than 100% or up to +125% of throw. This adjustability SHOULD get all but the poorest of dual elevator setups matched.

You WILL find that the elevator halves track much more closely with the DX7.

You may not "see" it, or "feel" it, but it's there. It is decreased "latency" and has been designed in to ensure the TX sends those channels to the RX, and the timing of the pulses perfectly synchronised.

It's tighter, faster, and better than any others I have ever had.

Tim Kearsley10/04/2008 14:14:00
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That's very interesting Timbo.  I actually used the article I linked to earlier for my guide (by Mike McConville) but in essence it's the same.  I've found the adjustment or travel, mid-oint etc. to be very simple and straight-forward.  Hopefully (weather permitting), I'll give the model its maiden flight this weekend.

Tim.

Tim Mackey10/04/2008 15:18:00
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20920 forum posts
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Best of luck then Tim...with a pilot named Tim...it will be fine
Tim Kearsley10/04/2008 15:52:00
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Thanks Timbo.  But then you haven't seen me fly......
birdy11/04/2008 11:52:00
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If you can, I would use mixing... Less plugs to break ect and I imagine you dont want to have to buy all the Y lead stuff, when you've got a free solution at your fingertips.
Bill Brownlie14/04/2008 12:26:00
37 forum posts
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Thanks for the info. I built this some months ago with futaba gear and didn't have this option. Had it all set up and ready to go with the Y lead but never got a chance to fly it.

Recently came back from the states with a load of Spektrum gear and changed the receiver over on the extra without changing the set up will need to have another look and see if I can reduce the electrics.

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