Wiring & Power Supply

I have a TReX Jr Dual Motor controller with 2 x 100:1 Mini Metal Gearmotors (Key specs at 6 V: 140 RPM and 90 mA free-run, 15 oz-in (1.0 kg-cm) and 0.8 A stall). Will be connecting 2 10k pots to the motor controller. Can someone recommend the appropriate wires/connectors & batteries to power this setup. Did I mention I need to run the motors continuously for an hour. As you can tell I’m a beginner at this, so should you need additional info regarding application I’ll be more than happy to comply.



What is the purpose of your two 10k pots and how are you planning to connect them?

If you need the motors to run for an hour, you need a battery that has a high enough capacity to run the motors and the controllers. First, you should figure out how much current your system will use while it is running. You can measure the current drawn from a battery with a multimeter. If you find your system draws 700 mA, for example, you will need a battery that has at least a 700 mAh capacity. Please note that the current drawn by the motors will very with the load applied to them.

- Ryan

Hi Ryan, the 2 10k pots will be used to control the speed of the two motors and will be connected to two of the analog (- + signal) terminals of the motor controller. What kind of wire & connector should I aquire? Thanks.


You haven’t given enough information about your project to give great advice about wires and connectors. What are your motors doing? What is the goal of your project?

For the motors you could do something like this picture:

I made that using pre-crimped wires and crimp connector housings along with some soldering.

Our premium jumper wires might work well for your other connections.

- Ryan

Hi Jan, Considering my project is going to be stationary and not on wheels, could I utilize a wall-adaptor power supply to power the system instead of batteries? This would allow me to run the motors for an hour and not have to be concerned about batteries discharging.

The motors are turning the gimbals of two gyroscopes. The gyroscopes in turn are set in a stationary structure.

It’s possible; just make sure that whatever you get can deliver the current you need (I’d say at least a 2A unit) and that the voltage is regulated (a lot of cheap wall warts have a much higher voltage than the nominal voltage when the load is small).

- Jan

Would you recommend any of the wall warts Pololu currently stocks? Would the 9V wall wart be too high of a voltage for the100:1 Mini Metal Gearmotors? And if so could you recommend a supplier? Thanks Jan.


Did you see how the name of that product we carry includes the 650 mA rating? 9V is not necessarily too high, and I don’t have a recommended supplier. Maybe even Radio shack might have something, and you might be able to get away with less than a 2A unit if you aren’t working the motors too hard.

- Jan

Hi Jan,

Would a 12V, 2.1A wall wart suffice?


Hi, Horus.

I’m pretty sure 12 V is a bit much for those motors.

- Ryan

I think the 12V wouldn’t necessarily be a deal breaker as long as you don’t give the motors too much power. You should also make sure that the 12V unit is actually regulated to something close to 12V; the unregulated versions will give you close to 20V when the load is small. In general, though, higher voltage operation will lead to a lower life, and we don’t have the exact trade-off characterized.

- Jan