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Gobble Squabble: Motor Controllers

Gobble Squabble: Motor Controllers

You’ll need motor controllers, also known as “ESCs”, to enable you to drive and operate your robot. Together with the RC transmitter and receiver, the controllers vary the actual voltages sent to the robot motors so you can change the robot speed and direction, as well as operate the weapon(s). Key design and selection considerations for ESCs include:

  • The drive motor ESCs must be designed for brushed DC motors, and must be reversible. (Brushed motor ESCs are becoming uncommon, and most of the ones available are NOT reversible. They are designed for boat and airplane models where the motors only ever turn one direction, not for robots.)
  • If you’re using a brushless motor on your weapon, you’ll need a brushless motor ESC to run it. Brushless motors ESC are generally NOT reversible, which is OK for your weapon. If your weapon must be reversible, use a brushed motor and ESC to drive it.
  • The ESCs must be rated for the voltage and current your robot motors will use. Many of the available ESCs are NOT rated for use with 3S LIPO batteries. 10A current ratings or higher are common, and will work well for your robot drive motors that almost never draw more than 1A.
  • Many, but not all, ESCs include a BEC circuit to power the RC receiver (and any servos in your robot). If none of your ESCs have a built-in BEC (you only need 1 BEC in your robot), you’ll need to build one separately. More info about how to do this is provided here (hint: for robots that only run 3 minutes at a time, the capacitors and heat sink are not needed).
  • Servos don’t need external controllers — they can plug directly into the receiver and obtain both supply voltage and control signal from it.

Sources and Models for Brushed Motor ESCs

  • Fingertech: this is a great little ESC that can handle anything your Antweight combat robot will need, including 3S LIPOs. It includes a BEC and requires the least modification of any of these ESCs. But it also costs the most and is often out of stock.
  • VEX Motor Controller 29 (and also here): this is the most tested ESC in this list, but mostly in VEX educational robots. It’s cheap and can handle much more than the specs say — easily including 3S LIPOs and up to 5A each. But you’ll do a lot of soldering with this one, as the leads and connectors need to be modified. Its physical size can be reduced significantly by squeezing off the case (and wrapping with 1 lap of electrical tape) and trimming the leads.
  • HobbyPower 10A Brushed ESC: a nice medium-small inexpensive unit that has worked very well in the past. It’s rated for use with 2S LIPO batteries only, but some batches in the past have worked with 3S batteries. To make it smaller aned lighter, trim off the power switch (not needed) and short those 2 wires together, then insulate that connection.
  • Experimental: some very-low-cost combination transmitter/receiver/ESC devices have become available recently, replacing $70 of recommended equipment for $15. These probably have the quality of a cheap RC toy, but we have one on order and will test and report on an update to these posts.

Sources and Models for Brushless Motor ESCs (useful for brushless weapon motors)

  • Amazon (a nice combination of ESC and brushless motor, including BEC; but the ESC is relatively large)
  • Amazon (very small ESC, without BEC)
  • Fingertech (no included BEC)
Two examples of brushed DC motor controllers that are useful for Antweight combat robots

This information is original work by Techno Chaos and is published under the terms of Creative Common license mode Attribution-NonCommercial-ShareAlike (CC BY-NC-SA).