Let's Make Robots!

HiTec Servo Hack

Servo becomes a geared dc motor

Just finished another walkthrough about hacking a HiTec servo and make it spin continuosly.

Follow it on flickr: http://www.flickr.com/photos/guibot/sets/72157617531839610/

Instructables: http://www.instructables.com/id/HiTec-Servo-Hack/


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Just removing all electronics but the motor?


I don't get it, why is this smart? Would it not be cheaper and simpler to just buy a geared motor then?

Have a look at this:


With that method, you can control the speed of the motor by standard servo control methods afterwards. As far as I am concerned this is the smart thing about "hacking a servo", and not just using geared motors - or am I the one missing the point? Or is there a point at all :D


I guess the point is transform the servo and make it a geared dc motor.. instead of using as a normal servo even for continuos rotation.

Imagine you really need a dc motor and you don´t have any shop around where you can buy a decent dc motor, and you have some servos in a bo.. so let´s hack them, oh and you really want dc motors instead of modified servos   :)

I prefer this way.. It´s just a matter of choice  :D

Had a servo electrically fail on me before. Instead of tossing it, I gutted it like this, and another like it for a diff drive robot. Was better than tossing the one out, still got use from it. Another robot builder I knew removed part of the case of 2 servos like this, so they could be fit together to fit in a narrower space.

The servo h-bridge can be slightly less of a driver than needed in certain applications. Some (older,cheaper) servos have BJT transistors for the h-bridge, which use part of the voltage given to them. Additionally, the servo circuit also has a limit pulse drive of the motors. Using your own h-bridge (FET based) and electronics gets more of the power to the servo motor for better torque and speed.

But you do lose the convenience of the driver being already contained in the servo. Unless you use one of these. But that brings back the voltage loss on the h-bridge transistors too.