Components marked with a "*" are optional, are usually not be needed.

The only components that you may want to use are the 22uF cap and the resistor RG, they are used to control the gain on the I.C., the I.C. has a gain of 20 without any components between pins 1 and 8.

If you need more gain you can add the cap and resistor to have as much gain as 200 !

e.g.

For a gain of 50 use a 680 Ohm

For a gain of 100 use a 180 Ohm

For a gain of 200 use only the capacitor ( do not add a resistor)

The power supply voltage ( VS ) can be between 5-12 Volts DC

You can use any type of speaker, but a 8 or 16 Ohm can produce the highest volume level on this I.C.

This board can be used for signal tracing during radio fault finding, i actually use this very circuit when i am trying to locate an audio signal during fault finding.