With this circuit it is possible to vary the resistance by adjusting the mark/space reaction of the 555. The circuit was found in the November 1989 Radio Electronics magazine.
This high frequency modulator was found in Motorola's 1990 Linear Databook. The current depends on the...
This circuit was found in an old Electronic Design used to apply digital signals to an analog...
Based on the frequency of the power grid, this circuit produces square signals for use in digital...