Step 1: Parts List
-3 alligator clips
-22 awg solid core wire
-7805, Voltage Regulator
-2 Synchronous 4-bit counters (74HC193N)
-4 1kΩ resistors
-1 1µF capacitor
-speaker and audio cable or headphones
-graphite pencil and paper
Step 2: BUILDING THE TIMER CIRCUIT
Step 3: BUILDING THE 4-BIT COUNTERS
Build another 4-bit counter the same way. Instead of connecting the input at pin 5 to the 7555, connect it to pin 7 of the previous counter. The yellow wires in the picture are running the output to a different spot on the board for easier access.
Step 4: BUILDING THE GRAPHITE MIXER
Connect one end of the graphite to the tip of the audio/headphone jack via an alligator clip. This is the red clip in the picture. Connect the other end to the breadboard’s ground (white clip). Connect the sleeve of the jack also to the breadboard’s ground (black clip). Connect the 8 outputs from the board to the mixer via long wires with exposed ends.
Step 5: POWERING THE CIRCUIT/GETTING SOUND
To get sound, make sure your mixer is connected to a speaker through the audio jack. If you don’t have this, headphones work just fine. You will have to press down on the wires so that the exposed tips connect with the graphite. The graphite acts as a variable resistor. By changing the wires position on the graphite, you change the amplitude of one of the components of the sound!