TREX for combat robot

Support Motor controllers/drivers and motors
1

Hello,
I recently purchased a new TREX (3 channel) to replace 2 ESC’s on a 3 pound beetleweight bot with horizontal drum spinner.
Currently I use a Ragebridge for the 2 brushed drive motors (25mm 6V 220rpm 1:45 gear ratio), and I use a Pololu 24v23 5.5-40V, 23A Motor Controller for the weapon motor which is an 18V drill brushed motor. A single battery powers both (2S 7.4V LiPo 1100mAh high output) for about 6 mins. The 2 ESC’s I currently use work well but I wanted to save some space and weight with the Trex.
I realize with the Trex the weapon will be uni-directional but I will just need to deal with it when the bot gets flipped. I like the channel 4 flipped mode of the Trex though, that should help with driving when flipped.

I’m looking for advice on a few items (so that I don’t immediately damage the new $100 controller):
I would like the mount the Trex to the bots carbon fiber body. I would like to bolt it but am considering tie-wraps with cushioning since I don’t see any dedicated mounting holes on the Trex board. I’m also considering coating the underside of the Trex board with high-temp gasket sealer to prevent any unintentional shorting underneath. Any thoughts on whether any of these suggestions would damage the device due to cooling issues would be appreciated.
Another question I have is what type of response should I expect from the auxiliary motor if I solder the diode on backwards? I’m currently using a Skyfly transmitter with a dial to control with weapon motor. It allows me to ramp the speed in both directions. Would this be a problem for the Trex if I ramp the speed in reverse even though it would be a uni-directional motor?
-Mark

2

Hello, Mark.

It should be fine to use some non-conducting coating on the bottom of the TReX. An alternative mounting solution you might consider is replacing the current hardware that holds the two boards together with something that still hold the board together, but also mounts to your robot.

If the fly back diode is connected backwards, it will basically be a short from motor power to ground as soon as you try to driver the motor.

The auxiliary motor on the TReX uses the full input range of channel 3, with one end of the channel range being no speed and the other end being full speed, instead of the center of the range being no speed. You can change the input range of for channel 3 by following by calibrating the channel. You can find the instructions for the calibration in the “Automatic Calibration for Your RC/Analog Controller” section of the TReX user’s guide.

By the way, the TReX has a lower continuous current rating than our 24v23 Motor Controller, so you should make sure that the TReX can handle the amount of power required by your motor.

Grant

3

Good info. Thank you for the reply.