Den 2007-12-17 23:17:09 skrev alan smith : > This is actually a two parter. > First, looking for a source of small quiet DC motors. The client has several types and are cheap and noisy. I pointed this out....dont you want something quiet for this product...heads nodded. So it doesn't need much tourque, its driving a small conveyor type thing and you can easily roll it by hand and shouldn't ever bind up. So, looking for some sources (domestic USA preferred) for small DC motors, 12V operating voltage. I use BOSCH. They mass produce nice grear motors for cars and sell industrial versions too, happily also in low quantity Think widscreen wiper motor, door window motors etc. Good price, quiet, reliable. If noise and/or long life is important use a larger motor but 24V type and run it at 12V. > Second....is adjusting the speed. Cheap and dirty is to just trim the voltage but then you have all that power being disipated by the resistor. Better is PWM? Probably. My father have a MIG welding machine and the linear regulator for wire feeder hav enow broken twice because of overheating. I think it would have been cheaper if it was a PWM too, to avoid the mechanically complicated fittign of mechanically protected cooling fins-- that still do not work... -- Morgan Olsson -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist