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How to Build a Sound Circuit

Sound circuits electronically produce or modify electrical signals in the audio frequency range. Literally thousands of circuit designs exist, employing many different approaches; one of the simplest uses a CD4069 integrated circuit (IC) to generate a wide range of tones. The CD4069 is a hex inverter, containing six separate inverters, three of which are used by the tone generator circuit. Though this IC sees use primarily in computer circuits, it works well in this application also. In addition to the IC, the circuit needs only a handful of other components.

Things You'll Need

Solderless breadboard
CD4069 integrated circuit
9-volt battery clip
Assortment of 22-gauge jumper wires
15K-ohm, 1/4-watt resistor
.47-microfarad capacitor
1K-ohm, 1/4-watt resistor
9-volt battery

Instructions

- 1
  Touch a cold water pipe or other electrical ground to safely discharge any static electricity from your body. Excessive static electric charges can damage the CD4069 IC.
- 2
  Insert the CD4069 into the solderless breadboard. Note that the breadboard has a horizontal slot running through its middle; the IC straddles this slot.
- 3
  Connect the positive, or red, battery clip wire to the IC's pin 14. Insert the end of the wire into any hole in the breadboard in the same vertical column as the IC's pin. The holes in a continuous column are all internally connected, so by placing wires in the same column connects them together. The IC slot interrupts the column at that point, so you can make proper connections to opposite sides of integrated circuits.
- 4
  Connect the negative, or black, battery clip wire to the IC's pin 7. Insert one lead of the capacitor so it connects to pin 5. Connect a short jumper wire to pins 4 and 5. Place another short jumper wire connecting pins 2 and 3. Insert one lead of the 15K-ohm resistor to pin 1. Place the other lead in an unoccupied column. Insert one lead of the capacitor so it shares this column. Insert its other lead so it connects to the IC's pin 4.
- 5
  Connect the 1K-ohm resistor between pins 1 and 6.
- 6
  Set the end of a 10-inch wire so it connects to pin 6. Connect the end of another 10-inch wire to pin 7. These are the sound circuit's output wires. Connect them to a small speaker or amplifier. Snap the 9-volt battery into the clip. You should hear the circuit make a buzzing tone. The circuit's frequency is about 1,300 Hz.

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