Need Help on a project

Hello,
I would like to recieve inforamtion and/or circuit design on PWM
(Pulse Width Modulation) dc motor speed control.

Thanks from advance,
BigT

Heres one that uses a 555 timer for PWM and uses two single pole relays to control motor rotation direction.
**broken link removed**

Heres a much larger diagram (based on the one above) of circuit that can control the speed and direction of rotation of 4 DC motors.

I designed and built this circuit a couple years ago to control motors via the parallel port of my computer, if you dont need computer control simply leave out the DB25 connector and use pushbutton switches or what have you.

http://www.geocities.com/nettron1000/ParaPort3.html