Triangle Wave Oscillator

Posted on Feb 5, 2014

This oscillator circuit is designed to generate both a rectangular wave and a triangle waveform, around 1kHz to 10kHz. The first operational amplifier in the chain generates the square wave, while the second operational amplifier generates the triangle wave. The LM101 is set up as an oscillator which swings rail-to-rail producing the square wave p

Triangle Wave Oscillator
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ulse to the limits of the voltage supplied by the Vcc lines. The LM107 is configured as the classic operational amplifier Integrator circuit. The LM101 is configured as a threshold detector, with the grounded minus input being used as a reference level. However because of the feedback being applied to the plus input [from the output pin] the voltage comparator also exhibits hysteresis. That is if the plus pin was just used had an external voltage applied than the circuit would just function as a voltage threshold detector. The signal being applied to the input is developed by the voltage divider form by the 10k and 8. 2k resistors. The true input to the circuit arrives from the LM107 through the 8. 2k resistor, but the input to the plus pin combines feedback from the output, which than adds the hysteresis. The threshold trip point is adjusted by the 1Meg resistor The LM107 side of the circuit is the integrator and produces the integration of the rectangular wave, or the resultant triangle waveform. The 0. 1uF capacitor, 1. 4k resistor and 140k adjustable resistor combined with the LM108 form the integrator. The oscillation frequency is determined by the product of the resistors and capacitors [RxC]. The frequency of the oscillation is adjusted by the 140k resistor. Although changing the trip point, by adjusting the 1Meg resistor also effects the frequency. The square wave output will be from rail-to-rail while the triangle...

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