Motor resistor?

Namuna · #1 07-27-2004, 09:55 PM

When I was doing a transplant the other night, I saw this little devil:

Sorry for the flash overexposure, the numbers read 6.3v and 22uF

One end was soldered inline with the tan wire going to the motor housing where the endbell touches, the other end was soldered inline with the white wire going to the motor housing where barrel of the motor touches.

I thought I read someone mention this is a resistor to step down the voltage going to the motor?

Anyone have more insight?

Thanks.

rfnagel · #2 07-27-2004, 10:35 PM

Quote:

Originally posted by Namuna
I thought I read someone mention this is a resistor to step down the voltage going to the motor? Anyone have more insight?

Negatory, that's not a resisitor, but rather a capacitor (22 microfarads). Now, while some folks have reported some insane increase in speed when removing it (I'm a bit dubious about that), the purpose that it's supposed to serve is simply a filter cap. It's supposed to prevent radio frequency noise (interference) from the motor (any brush type motor is naturally noisy, as far as RF - transmitter/receiver radio waves) to the receiver.

Namuna · #3 07-27-2004, 10:50 PM

Thanks for clearing that up rfnagel.

Azimov · #4 07-28-2004, 01:56 PM

Yup, a filter cap it is. But, it's an odd one. That's an electrolytic cap. It has a definate polarity. Usually, monolythic (disk) type caps are used for this purpose as they have no polarity. It makes me wonder if replacing this cap with a monolythic cap of close to equal value may increase speed in reverse. See, when the motor reverses, the polarity flips. But, this little bugger is still hooked the other way. Power to this cap is then flipped and it's hooked up backwards. It's like sticking a teeny tiny battery in the wrong way in the motor circuit. Namuna, have you noticed any increase in speed? Particularly in reverse after removing this capacitor?

rfnagel · #5 07-28-2004, 04:14 PM

Quote:

Originally posted by Azimov
Yup, a filter cap it is. But, it's an odd one. That's an electrolytic cap. It has a definate polarity. Usually, monolythic (disk) type caps are used for this purpose as they have no polarity.

Not neccessarily. Hate to disagree with ya, but most all power supply filter caps are electrolytic (usually quite large ones too). Dunno about small circuitry like the Zaps' PC boards, but a lot of electronics use larger electrolytic caps as filter caps.

Azimov · #6 07-28-2004, 04:31 PM

Thanks for the correction. The RC cars I've played with/torn into always had monolythic disk caps across the motor leads. I still wonder about reversing the polarity across an electrolytic cap. Especially a larger value. Just doesn't seem efficient to me.

Bad Company · #7 07-28-2004, 06:26 PM

Huh? What are yall talking about??? Some foreign language?? Now if you want to talk paints, I can understand that.

I never was the electronics type, but if I keep hanging around you guys, I just might learn something.

Azimov · #8 07-28-2004, 08:14 PM

LOL< yah, it's called Geekspeak.

Namuna · #9 07-28-2004, 09:28 PM

Quote:

Originally posted by Azimov
...Namuna, have you noticed any increase in speed? Particularly in reverse after removing this capacitor?

Sorry man, I never bothered to really test the setup without the capacitor.

rfnagel · #10 07-28-2004, 10:21 PM

Quote:

Originally posted by Bad Company
Huh? What are yall talking about??? Some foreign language?? Now if you want to talk paints, I can understand that. I never was the electronics type, but if I keep hanging around you guys, I just might learn something.

Essentially, no matter how many jigawatts that ya pump into yer flux-capacitor, she ain't gonna go much faster GDR LOL! -

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