I am using the trex jr motor controller in RC mode, 2 channels, each controlling one of the motors.
I have calibrated the controller. When I run either motor at full speed, I have no problems, but when I try to set a slower speed, the motors will turn, but I hear a loud squeal noise. I can’t imagine this is good. The red and green lights for the motor are both on when there is a squeal.
What is going wrong???
Any help would be greatly appreciated.
Is the squeal coming from the TReX or from your motor? What motor are you using and what is your power supply?
The motors are 7.2V DC gearhead motors, I don’t know what brand. At the moment we are powering them with a 5v (3A) power wall adapter. We don’t have a bigger supply at the moment, but directly powering the motor worked fine. It is difficult to tell where the noise comes from, but I think from the motors.
Both lights for the direction indicator (for each motor) come on. Is that a bad thing, or normal?
It is normal for both direction LEDs to light when the motor is connected and not moving at full speed. To achieve variable speeds, the motors are driven with a pulse-width modulated (PWM) output. This means that the motor outputs are constantly alternating between drive and brake. During the drive portion of the PWM cycle the correct motor direction LED is being lit, but during the brake portion of the PWM cycle the residual current passing through the motor loops through the other direction LED, causing it to light. As a result, it appears that both LEDs are on. If you disconnect the motor, you should notice that only one direction LED lights. Similarly, if you run the motor at full speed, there is no brake portion of the PWM cycle and you should see only one LED lit.
If the TReX Jr board itself is making noise, something is very wrong. If the gearboxes in your motors are making noise, you are experiencing an issue with the motors themselves. Please try to determine where the noise is coming from. If the noise is from the motors, can you test each motor individually to see if the problem is with a single motor or with both motors? Another useful test would be to directly power the motors at a variety of voltages ranging from 0 - 7. This would tell you if the squeal was being caused by the voltage level or the cyclical nature of the PWM output.