I made an Electronic Piano. The whole circuit gets power from a 9V Battery Snap. The 8 Button Switches that represent the Do, Re, Mi, Fa, Sol, La, Si, Do keys, have the energy flow restricted by 4.7 Ohms per button. There are two slide switches. One adjusts the frequency of the keys, and the other turns the circuit on and off when powered. The switch that adjusts the frequency has the energy flow restricted by 10 Ohms. The other has a restriction of 330 Ohms. In order for the circuit to make a sound, the circuit has a Terminal Block. This Terminal Block is used to connect to a speaker. It is also connected to two capacitors. A 220uF and a .01uF capacitor. The 8-Pin Dip IC Socket is used to hold the IC 555 Timer. One of the uses of this timer is as an oscillator. It produces an alternating current which is used for audio and frequency generation. There is also a 3.5mm Mono Jack Socket. This can be used to plug headphones in. The remaining three capacitors are also connected together and power this socket. The second 220uF Capacitor also goes to the right-most resistor. The Diode on the circuit controls the flow of energy from the top half to the bottom half of the circuit. I actually sautered this diode the wrong way originally. Which was complicated to deal with. Even on the wires popped out when writing this. This wasn’t as bad as correcting the diode.