Speed Control Motor 12V low side PWM
This circuit can switch a fairly high amount of current, an IRFZ34N MOSFET can handle over 35 Amps if connected to a proper heat sink. Higher power FETs, such as the IRFZ48N or IRF1010Z can be substituted if even larger currents are required. It is also possible to connect multiple FETs in parallel for even more current capacity. Always use thermally conductive grease between the FET and the heat sink, and remember that the heat sink is electrically live. [....]
Other Link
PWM Motor Speed Controller - DC Light Dimmer by IC LM324
PWM DC motor control with SG3525
LM324 PWM Control Motor Speed
