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[DPRG] hacked servos responding differently

Subject: [DPRG] hacked servos responding differently
From: Rodent daweasel at swbell.net
Date: Wed Jun 13 23:52:55 CDT 2001

Each servo is going to have a slightly different neutral position -- thats
why R/C stuff has a trim control on it. I've looked over quite a few pages
on servo modification and there are many schools of thought.

Some suggest leaving the pot intact and connected, and modifying the gear to
keep it from turning the pot. A slot is cut in the pot so the neutral
position can be adjusted with a small screwdriver after removing the servo
horn. This is kinda cool, except you have to be sure the gear won't
accidently turn the pot.

Others find out what pulse value positions the servo in the center, then
measure the pot and replace it with a couple of resistors of the correct
value. The pot itself is left in place but modified to rotate 360 degrees.
This may require some careful measurements and cobbling resistors together
to get the right value. I doubt 5% resistors would work well for this.

Some suggest just using two resistors of the same value that totals up to
the value of the pot. This is an easy fix, but as you discovered, each pot
has a different neutral value.

As long as you can find a pulse value that will stop the servo, you should
be able to come up with values that will make both of them go the same

----- Original Message -----

> i've hacked two Hitec HS-303 servos the exact same way. i disconnected
> the POT and connected the wires to two 2.2k resistors (in a Y
> formation).
> however, they don't respond the same way. if i set the speed/signal
> (whatever the proper term is) to 4700 one will stop and stay in
> position, but the other will continue to move. why? am i wrong in
> assuming that they should both respond the same way??

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