DESIRED_WAVEFORM_GENERATOR

Published:2009/7/14 23:33:00 Author:Jessie | From:SeekIC

This is a filtered step-function generator in which the wave amplitude at each step is set by a linear potentiometer (R1to R4).With the potentiometers arranged in time order and side by side (the way they are in a graphic equalizer), the positions of the knobs describe the output waveform. The 555 oscillator, controlled by R5 and C0 or C2, sets the duration of each step, and (there-fore) also the wave frequency. Potentiometer R5 controls the step frequency and the capacitors define the frequency range. The output of the 555 is applied to the clock input for the 4017 decimal counter, which activates its outputs one at a time. The linear potentiometers divide the voltage of each output, and thus determine the output voltage at a given step point. The schematic shows potentiometers only in Q0, Q3, Q6, and Q9, but for smoother waveforms potentiometers should be at all of the outputs, except the CARRY-OUT pin. The composite waveform is now purified by the filter formed by R13, C4, and C5, so the output will be rounded. The amplitude is controlled by the LM386 audio amplifier's input. For high frequencies, replace the amplifier with a 741 or some other high-frequency op amp.



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