The article describes the methodology for building a clock controller that can replace the conventional controller used in the standard quartz clock.
The basic clock works on a simple stepper motor design that is pulsed every second. With every pulse the polarity gets reversed so as to flip the magnetic field of the motor.
In the clock controller, PIC12F683 is being used which is clocked externally using a 32.768 Khz clock crystal (using the LP oscillator mode). In other words the PIC is running at 32768 clock cycles per second which makes it easy to time the clock. To ensure good time-keeping, the firmware uses the overflow of timer0 to cause an interrupt 4 times a second.
The clock is pulsed via two current limiting resistors which limits the current drawn from the PIC and to the clock. Since the PIC cannot be operated on 1.5V, two AA cells that provide 3V are used. The resistors being used ensures that the clock module runs within its original arrangement. The two Schottky barrier diodes act as clamps ensuring that the spikes generated by the coil do not exceed the working limits of the PIC processor.