Parts List -
R1 - 1 Meg 1/4W Resistor
R2 - 100K Pot
C1 - 0.1uF 25V Ceramic Disc Capacitor
C2 - 0.01uF 25V Ceramic Disc Capacitor
Q1 - IRF511 MOSFET
U1 - 4011 CMOS NAND Gate
S1 - DPDT Switch
M1 - Motor (See Notes)
MISC - Case, Board, Heatsink, Knob For R2, Socket For U1
Notes
1. R2 adjusts the speed of the oscillator and therefore the speed of M1.
2. M1 can be any DC motor that operates from 6V and does not draw more than the maximum current of Q1. The voltage can be increased by connecting the higher voltage to the switch instead of the 6V that powers the oscillator. Be sure not to exceed the power rating of Q1 if you do this.
3. Q1 will need a heatsink.
4. Q1 in the parts list can handle a maximum of 5A. Use the IRF620 for 6A, if you need any higher.
5. This circuit is not a true pulse width modulation control. Because only the frequency of pulses varies, it is really pulse frequency modulation. This works, though not as well as true PWM.
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