Digital Piano

This is a “digital piano”. The core component is a NE555 timer IC. By shorting 2nd (TRIG) and 6th (THRES) pins of the NE55, the chip is configured in astable mode, causing the 3rd (OUT) pin to output a square wave.

The frequency of the square wave is determined by the charging and discharging speed of the capacitor, which is controlled by the total resistance of the circuit (potentiometer + resistor and/or LED).

After the square wave is generated, it is sent from the 3rd (OUT) pin of the NE555 to a buzzer, which produces a sound corresponding to the frequency of the square wave. By adjusting the potentiometer, the user can change the resistance in the circuit, which in turn changes the frequency of the square wave and thus the pitch of the sound produced by the buzzer.

My Final Version

Finally, I added a button to the circuit (on the left side), which allows the user to play the sound only when the button is pressed without having to manually control the wire.

Semi-Final Version

Here I replace one of the 1kΩ resistors with a LED, which allows the user to see the current flow in the circuit and feel the change in resistance when the potentiometer is adjusted.

My First Adjustment

I cleaned up the circuit by replacing the “wire-component” redundancy (e.g., wire-resistor to resistor only, wire-capacitor-wire to capacitor only) and aligned the components in a more organized manner (e.g., placing the similar components in the same row or column). This makes the circuit easier to understand and follow.

The given circuit diagram of the digital piano:

During the lecture, the circuit diagram and a breadboard prototype on TinkerCAD were given. However, due to the limitations of TinkerCAD, the spacing of each component is fixed, causing the circuit to be a bit overcomplicated.