Variable audio oscillator 20hz to 20Khz

Posted on Feb 25, 2013

To obtain a 1000:1 Sweep Range, the voltage across external resistors Ra and Rb must decrease to nearly zero. This requires that the highest voltage on control pin 8 exceed the voltage at the top of Ra and Rb by a few hundred millivolts. The circuit achieves this by using a diode to lower the effective supply voltage on the 8038

Variable audio oscillator 20hz to 20Khz
Click here to download the full size of the above Circuit.

The large resistor on pin 5 helps reduce duty cycle variations with sweep.

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