Two questions with this really... One: if my pump circuit is completely isolated from my drive circuit/radio,do I still need to cap the motors? My current project has the drive motors on an 12V system and my pump on a 6V system. The pump is turned on via an RC switch that drives a relay (diode included, of course) which closes the circuit from the pump battery to the pump motor. Two: I have heard that with 2.4GHz radios and an ESC that it is not necessary to cap drive motors. Now, it makes sense that a mag throttle system with a seperate receiver battery that caps are not necessary, AND I have driven a boat (mine again for the umpteenth time) that has an ESC, no receiver battery, but no capped motors (it works fine), but I have seen systems where an un-capped pump running of the same battery as the ESC/radio has issues when the pump running--i.e. my Kirishima last season machinegunning the stern gun when I turned the pump on. I would like ANY imput on this matter as my electrical theory remains very weak for a former Ham (I got my Novice when the Soviet Union still existed).
Personally, I always cap them. in the past I have seen two different modes of problems from brushed motors personally. one was direct interference with the radio transmission, the other is noise on either power or ground lines causing all kinds of weird grief.
What does this capping of brushed motors mean? I have brushed motors, 550's from Battlers Connection, the cheap can things. Should I buy better? Are they not good motors to use? I guess they are what is called brushed as the winding spins, right? Thomas
They're fine motors. Capping is important on any brushed motor to minimize radio interference. Important enough that I won't have a motor in a ship without it being done. At a minimum, solder a capacitor between the + and - terminals of each motor. I like to take two capacitors and twist one leg from each together, then solder the free ends to the + and - terminals, and the twisted pair end to the can of the motor. Maybe overkill, maybe not.
Aha - now that makes sense. I have this booklet called "250 Great R/C Marine Tips" and it has a blurb in there where it speaks about "Electrical Bonding". It reads: Quote: If your radio glitches despite radio-frequency capacitors on your brushes, the electrical "noise" could be generated by the propeller shaft rotating inside the metal stuffing tube. Ground the stuffing tube to the motor case by soldering a flexible copper lead from one to the other, and your glitches will be greatly reduced." I always wondered about those capacitors but nver know how they were attached. Thanks! Thomas
And... I now know that it is field noise versus signal noise--so unless your Rx is in a Faraday cage (a silly place for an Rx), cap every brushed motor.
I've never grounded the stuffing tube to a motor, ever. Two reasons: 1) In combat models the motors should be easy to remove and replace lakeside, in a hurry (as should most components). 2)I've never had interference caused by a shaft rubbing the stuffing tube.
