TT Gearbox Motor Wire And Capacitor

Micro Sawppy rover control board has evolved to a perforated circuit board with soldered connection (and a few bonus features like provision for voltage monitoring.) Every time I soldered wiring to support another motor, I tested it on my cardboard box rover testbed solving any problems that were exposed by the testing. Once all six wheels are turning and four corner steering servos moving, I was eager to install it in Micro Sawppy Beta 3 (MSB3) and see it move.

I didn’t want to disassemble MSB3 when I wanted to build a cardboard box rover test bed, so I bought some more TT gearmotors from a different vendor(*) to install in my cardboard box. It was the new lowest bidder of the day, and these motors came with the convenience of wires pre-soldered to the motors. The TT gearmotors on board MSB3(*) didn’t come with wires and I would have to solder them myself before I can drive MSB3 around.

One thing I noticed about the motors with convenient wires is that it didn’t have noise-reduction capacitors. They’re usually absent from simple toys, but anything with electronics usually put capacitors on these motors to avoid glitching the some other part of the circuit. They are certainly considered essential when the device also has any kind of radio communication. The remote control hobby world is where I first learned of their importance, some facilities wouldn’t even let you run your vehicle if it was missing these capacitors, because of the risk it would cause interference with others at the facility and not just your own vehicle. I’m not worried about that in the immediate term. Since the cardboard testbed would always be wire tethered sitting on a tabletop, I didn’t feel compelled to add capacitors. But MSB3 will care about radio noise so I followed Pololu recommendations for adding noise reduction capacitors.

There are three options: a single capacitor across the terminals, or two capacitors from each terminal to the case, or combining both for the best noise reduction. The last time I tried soldering to the case of these little motors, I melted white plastic from the endcap and destroyed the motor. I then tried to remove the plastic part for soldering, but they were only held by bent tabs of metal from the case and they broken off making it impossible to reinstall and again destroying a motor. So in the interest of not destroying motors, I’m going with the simplest option of a single capacitor across the terminals to get MSB3 moving.


(*) Disclosure: As an Amazon Associate I earn from qualifying purchases.

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