A Few Simple Components, DIY an Electronic Keyboard

555 timer 1

Button × 8

1 100nF capacitor

Various resistances: 390Ω, 620Ω, 910Ω, 1kΩ×2, 1.1kΩ, 1.3kΩ, 1.5kΩ, 6.2kΩ.

1 buzzer

22AWG installation wire

1 9V battery connector

1 breadboard

1 9V battery

The principle of this electronic keyboard is to use the steady-state model of the 555 timers integrated circuit to drive the tone of the speaker. Each note has a main frequency. This frequency is controlled by the frequency generated by the capacitor and two resistors in the astable mode of the 555 timers. Therefore, there is a very beautiful announcement to calculate:

Set RA and C to a fixed value, so that you only need to adjust RB to get a specific frequency. Therefore, the beautiful formula is here again

Because all the resistors are connected in series, the resistance value of each button needs to be added to the previous one. According to the size of the resistance, the tone of the button is also different. After precise calculation (don't ask how it is calculated), we can get in conclusion

Because the selected resistors are common resistance values on the market, there may be some deviations in pitch, but these deviations are not too large.

Next we need to simulate and draw the circuit diagram that needs to be installed on the 123D circuit simulator.

It should be noted here that the red and black wires must be matched, the red is connected to the positive electrode, the black is connected to the negative electrode, and the 8 connection pins of the 555 timers are installed. As shown in the figure, the bottom of the 555 timers is 1234 from left to right, and the top Make 5678 from right to left and start to run counterclockwise in the lower-left corner.

1, 2 connect the capacitor, buzzer red wire connection 3, etc., look at the circuit diagram and pay attention to the connection sequence.

Next, the order of the most important resistors from right to left is:

390Ω
910Ω

1kΩ

1.1kΩ

620Ω

1.3Ω

1.5KΩ