Motor suppression

[Paul Davenport]

Hi,

I am getting radio interference from a 6 volt 3 pole motor, which is not
suppressed.

My local model shop just told me to buy 'standard' capacitors, but of course
this is not a language my local electronics shop speaks.

Question is therefore, what kind of capacitors do I need?

Ta for any response.

Paul

[John Mianowski]

I use 0.1 uF ceramic (that's 0.1 micro-farad). Here's something that
may help your understanding of capactors in general:

http://www.uoguelph.ca/~antoon/gadgets/caps/caps.html

JM

On Thu, 13 Nov 2003 13:22:47 +0000 (UTC), "Paul Davenport"
<Davers00@btinternet.com> wrote:

>Hi,
>
>I am getting radio interference from a 6 volt 3 pole motor, which is not
>suppressed.
>
>My local model shop just told me to buy 'standard' capacitors, but of course
>this is not a language my local electronics shop speaks.
>
>Question is therefore, what kind of capacitors do I need?
>
>Ta for any response.
>
>Paul
>

[MikDee]

Paul, u need to put 1 cap between the motor terminals, then 1 cap on each terminal with one of the wires from each soldered to the motor can. 3 altogether.

[Paul Davenport]

Thanks for that, put what exactly is a 'cap' what uF value?

Ta for further advice
"MikDee" <MikDee.wwrqz@rcgroups.com> wrote in message
news:MikDee.wwrqz@rcgroups.com...
>
> Paul, u need to put 1 cap between the motor terminals, then 1 cap on
> each terminal with one of the wires from each soldered to the motor
> can. 3 altogether.
>
>
> --
> MikDee
> --------------------------------------------------------------------------
---------
> Posted from the RCGroups.com Discussion Forums.
> Visit us at http://www.rcgroups.com <------- Win free R/C Gear!
> View this thread at rcgroups.com:
http://www.rcgroups.com/forums/showthread.php?threadid=168790
>

[Tachikaze]

A " cap" is a capacitor and the value that is usually used is 0.1mF as mentioned by John.
These are very common capacitors and are not very expensive. I would look at getting a handful of them and keeping them around for other projects. I place them on all of my motors regardless of the quality of the motor.
What the capicitor does is filters out static interference that is generated by the rotation of the motor. It can make a lot of differnece in your redio performance when using less than stellar quality of motors.

[Pagemaster]

There's a picture at the bottom of this page.
http://www.offshoreelectrics.com/misc_tips.htm

[Jim McLaughlin]

"Paul Davenport" <Davers00@btinternet.com> wrote in message
news:bp3uia$p9b$1@sparta.btinternet.com...
> Thanks for that, put what exactly is a 'cap' what uF value?
>
> Ta for further advice

Mr. Davenport needs a "cookbook recipie for this, not a dissertation on
electronic theory.

I've been using a Radio Shack part, a 47 microfarad electrolytic
capacitor rated at 35 volts. The Rat Shack part number is / was 272-1027.

These are motors I recycled from when my kids used them with RC cars. I
think the are all "540" motors, though one may be a "380", if my failing
memory is accurate.

Three of these are on each motor, one across the brush leads / contacts, and
one from each brush to the case.

The + lead from the cap is soldered to the + side of the motor brush. The -
lead is soldered to the - side of the motor brush leads / contacts for the
cap across the motor brushes. On the caps to the casing, + lead from cap
soldered to + brush contact and _ lead soldered to case on one side. On
the other side, - lead from cap soldered to - lead on brush / motor contact
and + lead from cap soldered to case.

Why?

Damned if I know. Its just what all the folks doing RC cars were doing
with their motors at the time. Doesn't seem to have hurt anything.

These caps have relatively "big" cases. I think that there are caps in
smaller cases which will work just as well.

--
Jim McLaughlin

Please don't just hit the reply key.
Remove the obvious from the address to reply.

************************************************** *************************

[Jerry Shaw]

"Jim McLaughlin" <jim.mclaughlintheobvious@comcast.net> wrote:

>"Paul Davenport" <Davers00@btinternet.com> wrote in message
>news:bp3uia$p9b$1@sparta.btinternet.com...
>> Thanks for that, put what exactly is a 'cap' what uF value?
>>
>> Ta for further advice
>
>Mr. Davenport needs a "cookbook recipie for this, not a dissertation on
>electronic theory.
>
>I've been using a Radio Shack part, a 47 microfarad electrolytic
>capacitor rated at 35 volts. The Rat Shack part number is / was 272-1027.
>
>These are motors I recycled from when my kids used them with RC cars. I
>think the are all "540" motors, though one may be a "380", if my failing
>memory is accurate.
>
>Three of these are on each motor, one across the brush leads / contacts, and
>one from each brush to the case.
>
>The + lead from the cap is soldered to the + side of the motor brush. The -
>lead is soldered to the - side of the motor brush leads / contacts for the
>cap across the motor brushes. On the caps to the casing, + lead from cap
>soldered to + brush contact and _ lead soldered to case on one side. On
>the other side, - lead from cap soldered to - lead on brush / motor contact
>and + lead from cap soldered to case.

That capacitor arrangement probably won't work on a boat if the motor is ever
reversed. The electrolytic capacitor will at least not work if the voltage is
reversed, and may actually blow up due to internal pressure. Also, that size
capacitor is not that good at preventing Radio Frequency Interference (RFI) to
a radio.

Use ceramic disc capacitors rated at 0.1 microfarads, rated at least 50 or
more volts (they are usually in the 100 volt or more range) . Alternatively,
go to a hobby store that sells RC cars, and they will usually have capacitors
to suppress RFI. Be sure to tell them you will be using them on a reversible
motor, in case they try to sell you a polarized capacitor. If the package says
to hook a particular terminal of the capacitor to the positive, don't buy it.

As everyone else has said, hook up three of these to the motor. Two, from each
terminal to the case of the motor, and a third from one terminal to the other
on the motor.

>Jim McLaughlin

Jerry

[Steve Watkin]

Try astec
E-mail Address(es):
astec@astecmodels.co.uk


"Paul Davenport" <Davers00@btinternet.com> wrote in message
news:bp00j7$k2$1@hercules.btinternet.com...
> Hi,
>
> I am getting radio interference from a 6 volt 3 pole motor, which is not
> suppressed.
>
> My local model shop just told me to buy 'standard' capacitors, but of
course
> this is not a language my local electronics shop speaks.
>
> Question is therefore, what kind of capacitors do I need?
>
> Ta for any response.
>
> Paul
>
>

[Paul Davenport]

Just to knock this topic on the head, I did as suggested (three 0.1 uF
ceramic disk capacitors - soldered as described.

No interference whatsoever.

Thanks guys and yes, those of you who asked for jpgs and short mpgs I'll be
taking some this weekend.

Ta again.

Paul


"Steve Watkin" <Steve.Watkin1@btinternet.com> wrote in message
news:bpbagt$4k3$1@titan.btinternet.com...
> Try astec
> E-mail Address(es):
> astec@astecmodels.co.uk
>
>
> "Paul Davenport" <Davers00@btinternet.com> wrote in message
> news:bp00j7$k2$1@hercules.btinternet.com...
> > Hi,
> >
> > I am getting radio interference from a 6 volt 3 pole motor, which is not
> > suppressed.
> >
> > My local model shop just told me to buy 'standard' capacitors, but of
> course
> > this is not a language my local electronics shop speaks.
> >
> > Question is therefore, what kind of capacitors do I need?
> >
> > Ta for any response.
> >
> > Paul
> >
> >
>
>