john316

Do I need to use a matchbox to match up two analog servos on one aileron? I have heard that you only need a matchbox with the digitals as they produce high torque and current draw with as little as 1 degree movement off neutral whereas the analogs are a lot more forgiving of a slight mismatch in linkage geometry. Your Thoughts??

jmw[8D]

Lynx

If I'm not mistaken an FMA servo buffer will do the same thing as what you want your matchbox to do.

Lynx

BTW, if both servo's are being driven from the same channel through a Y connector you don't need anything at all. Matchbox or buffer.

Phil Cole

I depends on how well the servos match. I've seen some servos with 10% error at the end points. You could find the best matching pairs of servos with some simple testing with long pointers attached to the servos before installing them. This can work with digitals as well, but the matching has to be better.

You can put an ammeter in line with your battery and measure the current as you move the controls through their ranges of motion. You'll soon see if the servos are drawing excessive current.

Maybe it's not as critical with low end analog servos, but the high end servos will have more gain and higher current consumption, so will be more likely to draw excessive current when mismatched.

rmh

There is an easy test for any ganged servo setup:
first make all the linkage/arms etc., so that ALL geometry is the same -
then remove the servo arm attaching screw from each servo.
turn the radio on .
remove one arm whilst the setup is at center.
It should go back onto the servo , easily . adjust till this is correct.
Now hold the tx to one extreme position . repeat that test. write down any error.
now go to the other extreme movement - again write down any error.
Typically- if your geometry was good - all will work - I have yet to find a combo I needed to fuss with-simply by FIRST insuring all geometry is correct (Identical).
Once you have centered both (whatever 3) repeat the end throw test on th other(s).
don't do anything till you see what ALL the end throw errors seem to be.
At this point - you may have found that your geometry is at fault - -it happens.
change that as required , FIRST.
Now go back and repeat the center test then the end throw tests.
On any of the computer radios --if you change sub trim centers the ends will also shift.
stay at about 125% max throw each way as you do these setups - this will permit some sub trim re arranging if req'd.
Or ---- just keep adjusting the linkage till you give up and hope for the best- then ***** at the mfgr for giving you bad servos.

john316

So I guess the answer to my original question is a definite "maybe".

jmw