This article describes the Variable Frequency And Duty Cycle Oscillator CIRCUIT (1N4009). The content is very simple, very helpful. Components in this article can help you understand better understanding of this article. For example, in this article, you can go to find and buy these components:1N4009. A discrete oscillator circuit shown in the schematic diagram below is? a variable duty cycle and variable frequency oscillator, can be used to produce rectangular wave. This circuit has frequency range of 60 to 1,000 Hz. This circuit consist of one UJT (uni junction transistor) and two transistors that provide positive going output when emitter voltage exceeds NPN emitter voltage.