Hi Tom, It isn't critical. The main consideration is that you use a high enough frequency that the motor cannot vibrate significantly at that frequency. The ability to hear the PWM drive may also be a disadvantage to audible range frequencies. I recently used 19kHz PWM for small motors like yours with no problem. I have also used frequencies down around 100 Hz with no problem. There probably is a range of frequencies which is best, but the difference between that an 10 times more or 10 times less is,I would think, pretty small, although I have not done careful efficiency testing. I don't think that permeability will be an issue for any reasonable PWM frequency (less than 100kHz). Sean At 02:04 AM 3/27/01 +0000, you wrote: >Thomas, > >I don't understand much about the theory behind a motor. All I am looking >for is a typical PWM frequency of a regular R/C 4.5V DC motor. > >Regards, >Tom > > >>From: "Thomas C. Sefranek" >>Reply-To: pic microcontroller discussion list >>To: PICLIST@MITVMA.MIT.EDU >>Subject: Re: [OT]: PWM Freq and DC Motor >>Date: Mon, 26 Mar 2001 20:41:05 -0500 >> >>I suspect it has to do with the ability of the core to react to the >>particular exciting frequency. >>There must be permiability changes with frequency. >> >>Thomas N wrote: >> >> > Hi everyone, >> > >> > I am using PWM to control the speed of a 4.5V DC motor. Would you >>please >> > tell me at what frequency I should set the PWM to run at? What are the >> > advantages/disadvantages for low and high PWM frequency? >> > >> > Thank you very much! >> > Thomas >> > >>_________________________________________________________________________ >> > Get Your Private, Free E-mail from MSN Hotmail at >>http://www.hotmail.com. >> > >> > -- >> > http://www.piclist.com#nomail Going offline? Don't AutoReply us! >> > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body >> >>-- >> * >> | __O Thomas C. Sefranek tcs@cmcorp.com >> |_-\<,_ Amateur Radio Operator: WA1RHP >> (*)/ (*) Bicycle mobile on 145.41, 448.625 MHz >> >>http://hamradio.cmcorp.com/inventory/Inventory.html >>http://www.harvardrepeater.org >> >>-- >>http://www.piclist.com#nomail Going offline? Don't AutoReply us! >>email listserv@mitvma.mit.edu with SET PICList DIGEST in the body >> > >_________________________________________________________________________ >Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. > >-- >http://www.piclist.com#nomail Going offline? Don't AutoReply us! >email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body