Hello,
I want to build a large scale RC car. I need a powerful servo. I have searched quite extensively and have only found a couple of people who have hacked a common servo for the signal in combination with an external h bridge and the servos pot for position feedback to drive a wiper motor.
the links referred to in the above article are dead.
Is there an off the shelf board I can use to accomplish this?
Thank you for your time and efforts.
Kevin.
Thanks again Coleman,
I know gearing a servo down will give added torque but speed is also lost.
Jonathan, that board looks nice but the motor can peak at 10 amps, it is 12 volt. Does the first board have any protection built in?
Thanks for all the help!
I like Coleman’s suggestion, those servocity power gearboxes are not only powerful but easy to use. You can still go with your initial idea of “Servo Control of standard DC Motors”.
Certain DC motor controllers offer the feedback loop capabilities, allowing you to integrate an optical encoder or potentiomenter to create a super servo motor. Take for example the following products:
Pololu High Power Motor Controller (RB-Pol-17)
RoboteQ AX2850 (RB-Rob-03)
All you need to do is find out the nominal voltage of the wiper motor and it’s peak current consumption to be able to select the appropriate motor controller. Then complete the feedback loop to have your servo control of DC motors.
Keep in mind that this is not your only solution.
You may decide to obtain a microcontroller to perform the feedback loop. The microcontroller would therefore take input from your encoder/potentiometer and send commands to the motor controller.
This would allow you to choose a more suitable motor controller that does not necessarily offer advanced functionality and has the current capabilities that better satisfy your requirements.
A 9A time-delay fuse can be added if you want to play it safe. Unfortunately only rudimentary protection is included on the VNH3SP30:
-Undervoltage and overvoltage shutdown
-Thermal shut down
-It also appears that the VNH3SP30 offers overcurrent cut-off, but at 30A.
Hi Kevin,
One of our suppliers, ServoCity, has taken care of this. They use standard to giant size servos and add an additional geardown (and in most cases, a new potentiometer as well that can allow 180 degree, 360 degree, 450 degree or multiple rotation (they also give you the option of using the standard servo as-is, though a 5:1 geardown reduces the 180 degree travel to only 36 degrees).
Their top-mount gearboxes range in torque from 92 to 4,495 oz-in and you use them the same way as a standard servo. We will have their entire product line available on our website within a few months, so in the meantime, all items are special order. Alternatively, you can take a look at our the power gearboxes currently on our website, though you need to add and modify the servo yourself.
Hope this helps,
