RS Motors

baleisen · #1 04-28-2004, 02:44 PM

Can anybody explain the odd capacitor layout on the RS motors. I've never seen the can attached to the (+) motor lead before. I did my own motor rebuild with a Squat can, 2 ceramic disk caps, and the original electrolytic cap. (The black can) The motor works great.
BAE

#2 04-28-2004, 03:07 PM

It's first function is to reduce EMF, it's second function is to "try to" prevent a surge back to the main PCB and triger the brake lights circuit and lock the motor from a free spin when going foward and hitting rev really quick to brake. It might serve some other purpose but I'm not sure yet.

Hope this helps.

xmodSpeed · #3 04-28-2004, 03:29 PM

The small cap (tan disc) prevents high-frequency RF commutator to brush noise from infiltrating the electrical system of the car which can lead to RF-reception issues. It also helps to bleed any residual RF off the motor housing.

The large cap (black cylinder) is there to avoid in-rush currents from arching the brushes when the brake is applied. Like codedat said it also prevents current feedback from the "generator-effect". Mainly it is for brush arching during braking. That is why the Mini-Z motors do not have them ... they don't have the brake function.

The cylinder is not 100% necessary IF you use a good quality brush but don't skimp on the RF caps! They can protect the ESC and the motors from high-frequency harmonics on the ground which can slowly "chip" away at the transistor junctions.

baleisen · #4 04-29-2004, 10:56 AM

I'm concerned with having the motor can attached to the positive pole. I have a carbon graphite chassis with a stainless steel rear deck. I don't want anything to short out.

xmodSpeed · #5 04-29-2004, 12:35 PM

Yes, be VERY CAREFUL when using CF or metal parts! If you short it, you can destroy the ESC.

ALWAYS make sure the motor is insulated from the ESC/chassis. I run the Zero-Products CF Chassis on my Drag Supra and he has a special insulator on the stand-offs by the motor to prevent this.

In all reality, if you just add another ceramic disc to the positive side (from terminal to housing) and are running high-perf brushes like PNRacing sells (3 for $9), you will be fine without the larger cap.

baleisen · #6 04-29-2004, 08:14 PM

The motor I will use is xmodspeed's "S Tune" motor, along with the rest of the kit. I intended to use 2 disk caps and a 10 mF can. Any ideas? Any warnings? TIA.
BAE

#7 04-30-2004, 03:30 PM

If you are worried about the can sticking out you can always shrink wrap it and use the plastic motor mount but the motor will get hot if it is mod'd. Or you can try to find nylon screws and washers so the metal housing heat sink dosen't touch the CF chassis.

baleisen · #8 04-30-2004, 07:10 PM

I thought of that. I need to insulate the motor can. I was going to give it a PI network cap layout. Nylon screaws may not be strong enough. Its a problem. I also thought of epoxy enamalling the stainless steel but that isn't sure fire also. Isolating the motor can seems the best game.
BAE