PWM Speed Controller
This is a low cost project is based on the Dial-a-Speed design. This is a pulse-width modulation (PWM) speed controller, using a 555 timer IC wired in astable mode to control an N-channel power-enhancement MOSFET that actually switches the motor on and off. This circuit is cleverly designed to offer a wide range of control, and can produce square waves with duty cycles ranging from less than 5% to more than 95%, depending on where you set the dial.
I originally built the design exactly as shown in the Make article however I found all of the jumpers required on the board left the design rather messy. I opted to design a board for this project so I could just solder on the components and forget about all of the jumper wires.I am using the PWM to control the speed of a small DC motor that spins a magnet for a stir plate.
The schematic for this design can be seen in the Make Magazine Dial a Speed article, and the background details of the circuit can be found on the Dallas Personal Robotics Group page.
Parts list: (a slightly modified list from the Make Article)
- Circuit board based on this design
100K audio-taper potentiometer RadioShack #271-1722 (R1)
1N4001 micro 1A diode (3) RadioShack #276-1101 (D1, D2, D3,)
MOSFET IRF510 transistor RadioShack #276-2072 (Q1)
TO-220/TO-202 aluminum heat sink RadioShack #276-1368 (Mounted to Q1)
555 timer chip RadioShack #276-1723 (U1)
2-position PC board terminals (2) RadioShack #276-1388 (J1, J2, J3, J4)
100μF axial-lead electrolytic capacitor, 35V 20% RadioShack #272-1016 (C1)
0.1μF ceramic disc capacitor (2) RadioShack #272-135 (C3, C4)
10K resistor, 1/8W RadioShack #271-006 (R2)
- Silver tone knurled knob RadioShack #274-424 (Mounted to R1)
- Project Enclosure RadioShack 270-1805 (This is the enclolsure I used something different might work better for you)
- Procure circuit board
- Procure components
- Solder components to PCB
- Connect J1 to 5-12 VDC Power Supply
- Connect J2 to Load (DC motor, LED, etc)
- Connect potentiometer (R1) to J3 and J4
- Adjust potentiometer to enjoy variable speed intensity ect.