Q's on Dual Servo Setups

[Meniscus]

OK, here it is:

I'm thinking about running two servos on a boat for steering. I have my reasons for needing to use two servos, so let's not get into all of that. I merely have some general questions. Having never done this, I was hoping that someone could point me in the direction of some good info regarding this type of setup? I hope to answer the following questions: :unsure:


How much is the drain on the BEC and can it handle it (I know that this is servo specific a lot of times)?
Do I always need to run a separate batt (in place of BEC) to make this happen?
Any way to adjust center points on the "slave" servo (other than physically moving) (potentiometer circuit)?
Limit on size of servo or drain on BEC and or separate batt (in place of BEC)?
Any throw differences incurred when using different servos in tandem like this?
Interference issues that could be as a result of running current to the servos in various directions (antenna array)?

Go ahead and tell me if I'm off base and I should just wire up a Y and be done with it, LOL!

Thanks for the input.

[G Doggett]

I have used two standard servos ( Futaba 3003 ) in place of one high torque unit in the past.
I simply hooked them up with a Y harness from the receiver, so whether it was BEC or not made no difference, and centering was not an issue.
The only critical thing is they must operate in such a way that they do not fight each other, so mechanical set up is important.
Both servos and their operating arms and linkage must be identical to prevent any binding.
It is a simple way of doubling the amount of steering torque, particularly if you have a few spare standard servos lying around.
Graham.:rockon2:

[Meniscus]

Thanks Graham. The application is a little different. These two servos will both be steering, but not attached to the same steering mechanism. That's all I can say for now.

However, I appreciate you confirming that I could possibly do it with a Y, keeping in mind the specs. That is helpful.

[ED66677]

on the mechanical standpoint, you may want to have a look at how "we" use several servos "in serie" on a giant aerobatic RC plane, it's a kind of mechanical mixer with an intermediary horn!

[Meniscus]

I think I understand. However, these two servos will be independent of one another (not in any way mechanically attached), but the share they direction/input of the steering.

Maybe this is getting too complicated. Do you have an example picture of this "mechanical" mixer you are referring to? I'm not sure that it will apply, but now I have to know! LOL

[Meniscus]

This is sorta what I had in mind, but in the reverse direction to be fed to two servos:

http://www.astecmodels.co.uk/catalog/product_info.php?cPath=3&products_id=44

[Meniscus]

I have my solution!!!!

http://servocity.com/html/180o_servo_stretcher.html

Please don't wipe out the stock before I get the chance :tt2:

[ED66677]

I could not find any pictures of the mechanic mixer but imagine two servo in line, one behind the other and slightly below the front one, both servo have a pull-pull linkage, each right side linkage are attached to each end of a mixing arm (two mixing arm total), same for the left side, the center of each mixing arm is connected to each side of the rudder, the good thing on giant plane that uses two receiver for safety reason is that if one servo does not respond anymore, the mixing arm makes so that the second servo still can do his job, you then get half stroke on the rudder!
Hope that's clear!

[Meniscus]

Good explanation Ed, it makes sense now, thanks.