At 11:49 AM 11/20/99 +0800, Alan wrote: > I've seen on TV advertisement, a device which promises to bring down >electricity consumption. Interestingly, they show a test, wherein they >plug the device in one of the outlets where other appliances such as >refs, TV's, aircons, motors and the likes are also plugged in. The >ammeter shows significant drops in readings. Are these devices, safe to >use together with our appliances, do you recommend these kind of devices >? > I understand that these devices has something to do with power factor >correction, can you point some resources where i can learn more. >Is a PIC based power factor corrector feasible,can you give me hints on >how to go about it. If it is ok, maybe i'll push thru with it one of >these days.... These devices work for motors which have variable loads and idle a fair amount of the time. The original circuit was patented by NASA and is used on industrial motors to reduce cost. I've got one 'Watt Wizard' attached to my refrigerator. I suggest you search for the NASA patent. As I remember, the device controls the phase angle of the power to minimize power for a given torque. ================================================================ Robert A. LaBudde, PhD, PAS, Dpl. ACAFS e-mail: ral@lcfltd.com Least Cost Formulations, Ltd. URL: http://lcfltd.com/ 824 Timberlake Drive Tel: 757-467-0954 Virginia Beach, VA 23464-3239 Fax: 757-467-2947 "Vere scire est per causae scire" ================================================================