Copy of 556 PWM

Pulse Width Modulation using the 556 Dual Timer. Output period is set through the first timer which is a 555 Timer configured as a conventional astable multivibrator. Output pulse width is set through the second timer which is a 555 Timer configured as a monostable multivibrator. Adjustment is through Rpwadj. For the saved values: Period is roughly 1 ms. Pulse width is adjustable from less than 75 µs to greater than 975 µs.