Circuitos_1

Today we will build a circuit that uses the IC 555 along with buttons and resistances to play the 9 musical notes.

This circuit has a wave generator 555 configured as an astable multivibrator circuit. This type of operation is characterized by a square wave width output defined by the designer. The frequency of the output wave can be controlled by the resistance between pins 7-8 and 2-7 in addition to the capacitor connected to pin 2 and GND. The resulting frequency can be calculated according to the following equation:

Circuitos_2

Where the Req is the result according to the button being pressed.

This way we can make sound similar to a basic digital piano that regulates the output frequency for musical notes.

Notes are played on the following frequencies:

NoteFrequencyResistors
RE1493HzR2-R3
DO440HzR2-R4
SI392HzR2-R5
349HzR2-R6
SOL329HzR2-R7
293HzR2-R8
MI261HzR2-R9
RE246HzR2-R10
DO200HzR2-R11

This circuit has been adapted from a circuit that is in the following link.

Schematic

Circuitos_3_Schematics

Bill of materials (BOM)

Circuit:

  • 1x IC NE555P (U1)
  • 1x 10K Ohms Resistor (R1)
  • 2x 6K8 Ohms Resistor (R2,R8)
  • 2x 4K7 Ohms Resistor (R3,R6)
  • 2x 3K3 Ohms Resistor (R4,R5)
  • 2x 2K2 Ohms Resistor (R7,R10)
  • 1x 5K6 Ohms Resistor (R9)
  • 1x 8K2 Ohms Resistor (R11)
  • 9x SPST Button (SW1-9)
  • 1x 10nF Ceramic Capacitor (C1)
  • 1x 47uF Electrolytic Capacitor (C2)
  • 1x 100nF Ceramic Capacitor (C3)
  • 1x Speaker 8 Ohm from 0.25W to 1W

IC/Components Pin-out

Circuitos_4_Pinout

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