When testing the response of many pulse-width-modulated (PWM) systems, there's a need to independently vary a multivibrator's frequency and duty cycle. Such systems include dc motors, ultrasonic ...

Low-frequency voltage-controlled oscillators (VCOs) can be found in clocks, timers, audio synthesizers, and a variety of other applications. The VCO shown in Figure 1 is based on a simple astable ...

Figure 4. A snapshot, in time, of two complex numbers whose exponents, and thus their phase angles, change with time. The notion of negative frequency is often troubling to engineers who've spent so ...