This is the traditional H bridge configuration for motors. The circuit is for currents up to 500 mA, but with higher power transistors such as the TIP31 motors up to 2 A can be controlled.
This circuit is from a publication from the 50's. Inductive components are critical, and...
This simple two-transistor circuit used transistors from the 60s, having been found in a...
This circuit uses an oscillator that generates a signal of approximately 1450 kHz to test...