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Model Forum / Radio Controlled / Water Models / November 2003Motor suppression
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 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 >Hi, > [quoted text clipped - 9 lines] > >Paul Paul, u need to put 1 cap between the motor terminals, then 1 cap o each terminal with one of the wires from each soldered to the moto can. 3 altogether - MikDe ---------------------------------------------------------------------------------- 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=16879 Thanks for that, put what exactly is a 'cap' what uF value? Ta for further advice > 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 [quoted text clipped - 6 lines] > 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 > 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. *************************************************************************** >> Thanks for that, put what exactly is a 'cap' what uF value? >> [quoted text clipped - 19 lines] >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 Jerry Shaw said (and I quote): > 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 [quoted text clipped - 17 lines] > > Jerry What he said!  SignatureCheers, Alistair Harding - VK2LLL NSW Police Communications Operator (VKG3) Deputy Captain - Seahampton Rural Fire Brigade www.alistairharding.com / alistairdeletethisbit@alistairharding.com (remove deletethisbit) 'The impossible we do straight away - miracles require 24hr notice!' "Above statements are my own opinion and are not to be taken as official statements of my employing agency, nor should they be taken to reflect official protocols/policies of the NSW Police Service, NSW Rural Fire Service or the State Government of New South Wales, Australia." 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. -- Tachikaze Tachikaze ----------------------------------------------------------------------------------- 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 There's a picture at the bottom of this page. http://www.offshoreelectrics.com/misc_tips.htm -- Pagemaster '[image: http://www.offshoreelectrics.com/offshoreelectrics_anim.gif]' (http://www.OffshoreElectrics.com) ----------------------------------------------------------------------------------- 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 Try astec E-mail Address(es): astec@astecmodels.co.uk > Hi, > [quoted text clipped - 9 lines] > > Paul 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 > Try astec > E-mail Address(es): [quoted text clipped - 14 lines] > > > > Paul |
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