PIC-based speed controller (2)

The advantage of using a PIC for a project like this is that the component count is kept low. Take a look at the circuit diagram to see what I mean :-)


The 15V DC power supply is regulated down to 12V to give a constant peak voltage for the PWM output to the motor. The 12V is further regulated down to 5V for the PIC. Also on the left of the diagram are the three LEDs with series resistors, and the reset button for the PIC.

On the right of the diagram, the speed control button connects straight to one of the PIC I/O pins. The PWM output waveform goes to an opto-isolator and then a driver transistor.

In the actual build, I also added a diode in series with the 15V power supply to protect against accidentally reversing the connections.

Having designed the circuit using PCB123 Schematic, I worked out the stripboard layout using VeeCAD. Here is the layout.


I'll put up another post soon with details on the sources I drew on for writing the software.