We all love music!
It was always a fantasy to see how piano and musical keyboards work.That’s how we set out to do a basic music instrument using IC 555 timer chip.

To  make this instrument, we require some basic components :

  • IC 555 timer chip – 1
  • Resistors : 51 ohm-1, 1 kilo ohm-1, 6.8 kilo ohm-1,33 kilo ohm – 5 (or) 10 kilo ohm – (5)
  • Capacitors : 0.1uf-1, 100uf electrolytic capacitor-1
  • A 9V Battery
  • Piezo buzzer
  • Breadboard
  • Connecting Wires
  • A Sheet of paper and a pencil(graphite)

Now connect the circuit as shown in the circuit diagram.

circuit diagram




If you observe closely, IC555 timer has 8 pins. The corner of the IC555 timer has a round dot and that dot means the pin at the left bottom corner is pin 1and the one next to it is pin 2 and so on.

Working :

The IC555 timer chip sends square wavesto the buzzer which causes the buzzer to make the sound.The frequency of the square wave could be high, low or anything in between.The frequency is controlled by number of components in the circuit.One could control the frequency by varying the resistance between pin 7 and pin 6 where the 6.8 kilo ohm is present.The higher the resistance value, the lower the frequency and the lower the resistance value, the higher the frequency. Basically apart from the 6.8 kilo ohm which is already present between pins 6 and 7, we could also put different ranges of resistances in series with the 6.8 kilo ohm to vary the sounds on the buzzer.

It is interesting to know that we could play different musical notes by varying the frequency . These frequencies can be generated using different resistance values.Few of the musical notes with their corresponding frequencies are given below.


We have arranged five 33 kilo ohm resistors in series with the 6.8 kilo ohms and observed the variation in frequencies.And this is how it sounds!

There are various methods as to vary these resistances in order to produce different sounds. For example, the resistance can be altered by using a graphite-pencil.We know that graphite is not a good conductor of electricity and it resists the flow of current.You can use a sheet of paper and pencil to make a variable resistance sheet.If you put the varThe longer you move along the pencil mark,the lower the frequency we observe.This  is because the resistance offered by the graphite increases with the distance.Thus you can make a music sheet and play different notes.This is just one of the many methods to alter the frequency and listen to various musical notes.

This Article was contributed by
Anirudh, Shrutha , Kiran , Shri Ram of 3rd year ECE.

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