DIY Audio Function Generator Part 1

Posted on Feb 5, 2014

A simple low end Audio Function Generator. I want to be able to use the Sine Wave output to test ADC resolution and as a base band signal for RF projects and having very Low Total-Harmonic-Distortion (THD) would be nice. So I`ve decided to build my own Function Generator. Most DIY Function Generators I found online start out with a Square Wave Oscillator

DIY Audio Function Generator Part 1
Click here to download the full size of the above Circuit.

feed into an integrator to get a triangle wave, then you feed the triangle wave into a wave shaper and you get a rough Sine Wave output. This is similar to a project I built up last year. This method works, but the wave shaped Sine wave isn`t going to have the low THD I was looking for, so I am taking the opposite approach and starting with a Sine Wave Generator based on the #327 Lamp Wien-bridge Circuit to get the low THD. I`ll then feed that into a Comparator to produce the Square wave; I am then using the Square Wave to turn on/off a ramp generator circuit. I would rather have a ramp output vs a triangle wave. The ramp circuit will let me play around with different single & dual slope ADC concepts later on. I`ve added a +3. 3V Square wave output to be feed into a frequency counter, so I don`t need to bother to add a display to the function generator. Mine as well make use of the Frequency counter I have for a display, also having a +3. 3V square wave output would be nice for any micro projects later on. I`ll have a Freq. Adjust Pot, Freq. Range switch, Ramp Current Source Adjustment Pot, and an Output Amplitude Adjustment potentiometer. Below is a rough layout of the proposed design: After sketching out the concept drawings my next step was to test the Wien-Bridge Oscillator circuit I was basing this whole design around. I prototyped up the circuit with the Frequency Range Select switch and 10K pot and was pleasantly...

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    Automatic Intruder Alarm
    Bi-Color Indicator Circuit
    LM35 Digital Remote Thermometer circuit and explanation
    Electronic Spy Bug Circuit
    Switching intensity of LEDs
    circuit diagram of remote control tester
    double symmetrical power supply
    Privacy Telephone Intercom
    LED TesterCircuit
    sine wave oscillator
    C program to read and write raw data on SD card
    1Hz clock signal generator circuit
    Valve/Tube Low Frequency amplifier 30W