Pulse Width Modulation
You can control the amount of power the motor gets by using a switch and turning it on and off very quickly. https://web.archive.org/web/20081204151759/http://googleads.g.doubleclick.net/pagead/ads?client=ca-pub-2757683140936137&dt=1228386005879&lmt=1612436521&output=html&slotname=6542966663&correlator=1228386005879&url=https%3A%2F%2Fmayothi.com%2Fspeedcontrol3.html&ea=0&frm=0&ga_vid=463190824.1228386007&ga_sid=1228386007&ga_hid=1035464916&flash=0&u_h=864&u_w=1536&u_ah=834&u_aw=1536&u_cd=24&u_his=12&u_nplug=3&u_nmime=4&dtd=M If you want the motor to turn slowly, the switch is longer open than it is closed: If you want the motor to turn fast, the switch is longer closed than open: …