use a germanium diode because of the low foward voltage drop i.e in 60 or in270.. .3 vdc drop in conductance and then a series of caps ..i.e .01 then a 1 uf - 22 uf -100 uf-diode-1000 uf........this scheme worked for me when using a simple motor (maxium motor ) to recharge nicad batteries off a thing that you put in you're yard and the wings rotate...(pellican statue) then feed it to a ldo regulator ldo=low drop regulator@ 5 vdc.............just .02 worth..... -----Original Message----- From: Douglas Burkett To: PICLIST@MITVMA.MIT.EDU Date: Monday, November 08, 1999 4:02 PM Subject: Re: Disk drive spindle motors as DC generators. >Adam, > >Your basic idea is reasonable, couple caveats though. >You are gonna have to spin the motor fairly fast, if I remember correctly >disk spindle motors ran at about 300rpm. To use the motor as a generator, >you are gonna need a reasonable fraction of that to generate any appreciable >voltage. >Depending on the motors quality and construction. Maybe coupling via a gear >stepup system. The second thing to consider, storing power in the cap and >then using a linear regulator to drop it down. Any drop on the regulator is >wasted power. Not sure what solutions are available, but these you will >need to consider. > >Doug > >----- Original Message ----- >From: Adam Bryant >To: >Sent: Monday, November 08, 1999 11:38 PM >Subject: Disk drive spindle motors as DC generators. > > >> Per my previous question about using old DC spindle motors as DC >> generators for a PIC circuit I came up with a few more questions based on >> the fact that these motors originally ran off of 12 volts. >> >> Theoretically, these motors could generate more than 5 volts if spun fast >> enough. How would I efficiently limit the PIC supply to 5 volts? A low >> dropout regulator? >> >> How do I store excess juice generated during faster wind gusts for when >> the wind isn't blowing so hard. We tend to have very gusty conditions >> around here. The wind can be blowing 25mph one minute and 2 or 3mph the >> next. >> >> Could someone help me out with a basic circuit drawing? I am envisioning >> something along the lines of: >> >> +----|>|-----+-----VREG-----+ >> | | | | >> Motor Cap | PIC >> | | | | >> +------------+-------+------+ >> >> The motor generates DC of whatever voltage when spun, the capacitor >> stores it, the diode prevents the capacitor from spinning the motor, >> voltage regulator supplies 5v to the PIC. >> >> As always, apologies for the ASCII art and limited electronics knowledge. >> Adam >> >> >> Adam Bryant (age 0x23) >> adamdb@juno.com >> Parker, CO, USA >> Robotics, RC Airplanes, anything using a PIC >> >> ___________________________________________________________________ >> Get the Internet just the way you want it. >> Free software, free e-mail, and free Internet access for a month! >> Try Juno Web: http://dl.www.juno.com/dynoget/tagj.