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TRex Jr Motor Driver and FA 130 motors




I just got these products and I am trying to build an RC controlled robot. I have the TRex Jr controller and the Tamiya dual gear box with FA 130 motors. I hooked the TRex up to my reciever and configured it. I did a test with the LEDs and everything seemed to be working fine and I was getting a 5 V signal out of both motor outputs. When I hook up the FA 130 motors (with .1 uF capactiors across the leads) the drive LEDs flicker and the motors make a high pitched noise and do not turn. When I hook the motors directly up to a power source they turn normally. I realize the FA 130 motors are designed for 3 V operation but I was under the impression they would work fine with a 5V input and just have a shorter lifetime. 

 I am clueless as to why my motors aren't working. I know these motors have high current draw but the TRex Jr is supposed to be able to supply 2.5A to each motor which is above stall current for these motors. Does anyone have any suggestions? 

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motors are weird sometimes. Have you tried putting the motor and led in parallel?
The LEDs are surface mount on the TRex motor driver board and I have yet to find a schematic for the board. So I have no idea what configuration they are in and I don't really wanna mess with the board itself. I might just try some different motors. I have some more on order that take a lower current, but they won't get here for another week. Thanks for the suggestions though.
yeah, then just try hooking up a 10uF or so cap in series with the motors
No such luck with the 10uF capacitor. Same result as with the .1uF.

The battery was exactly the issue. Thanks everyone for the help. Now that I have the motors spinning I will try to get the thing all together tomorrow and put it up. I upgraded to the NiMh I had and the motors spinned. It is good to know that the high pitched noise is caused by not getting enough power to start the motor turning.

Thanks again everyone.