Pulse Width Modulator, with NE555 timer-oscillator

Parts List:
   R1 = 1K
   R2 = 47 ohm
   P1 = 50K potentiometer
   C1 = 0.1uF, (100nF), ceramic
   C2 = 0.01uF, (10nF) ceramic
   C3 = 470uF, 25V, electrolytic
D1,D2 = 1N4148, general purpose signal diodes
   D3 = MBR1645, NTE6081, or similar. 45V/16A Schottky Diode
   Q1 = BUZ11, NTE2389, MosFET, High Speed Switch, N-channel, 30V/35A
  IC1 = NE555, 8-pin Timer/Oscillator

Couple Notes:
This circuit is capable of regulating 12V motors and DC light bulbs. No coolrib required for Q1 or D3 if the current does not exceed 2A. If it does, a sufficient coolrib for both the Schottky Diode (D3) and MosFET Q1 is required.
The regulation is obtained via PWM or Pulse Width Modulation. The output pin 3 of the 555 provides square-wave with an adjustable duty-cycle. What that basically means is that the pulse width changes the speed of the motor. The output from the 555 feeds the mosfet via current limiting resistor R2 of 47 ohms. Because the MosFET Q3 only "switches" and is not behaving like a pot, its energy-waste level is negliable, and also provides the motor more coupling at low rpm. The maximum current Q1 can provide (safely) is about 10A. The replacement type mentioned in the parts list (NTE2389 can provide up to 35A at 60V. I use a cpu-cooler-fan for additional cooling at high rpm.