Electronic Piano G H Patel College of Engineering & Technology G H Patel College of Engineering & Technology Prepared by Sanjay Hadiyal ( ) Kevin Hirapara ( ) Chirag Ramoliya ( ) Guided by: Mrs. Geetali Saha

Introduction This is a simple toy piano using a 555 timer IC and a few basic components to create tones that that is sound through the speaker. An electronic piano consist of several electric components that produce a voltage signal with a varying frequency. This signal is fed to a speaker, which vibrates more or less depending on the frequency of the signal, hence producing sound of different tones. We need to build a circuit that will produce a voltage signal that varies its frequency within a range of audible frequencies for the human ear.

Components 6 x small buttons 1 x 10k resistor 10u and a 100n capacitor 555 timer IC and socket 8r speaker small piece of perfboard 9 v battery clip and switch wire leads solder + iron 470 ohm resistor 6 x 1K resistors 1 LED

The 555 Timer IC In order to produce a time varying signal, we need a component that works similar to a clock, producing a periodic signal whose frequency can be controlled in some way by the outer components connected to it. For this purpose, we use an integrated circuit or chip, called the 555 timer regulator The 555 timer regulator can be used to build an astable circuit. Astable circuits produce pulses, like a digital clock.

The 555 Timer IC In the figure, R1 has an arrow which indicates change. This is because R1 is a potentiometer, a resistor with a variable resistance Legs 2 and 6 are connected together so that the circuit triggers itself at every time cycle, behaving as an oscillator The capacitor labeled C, is charged through the resistors R1 and R2, but is discharged using R2 only The charge in C1 is between 1/3 Vcc and 2/3 Vcc (Here Vcc=+9V). The makes the oscillation frequency independent of Vcc.

Circuit Diagram

Picture of Project

Working We used 555 timer IC in this project. Frequency is inversely proportional to time and time period depend on charging and discharging of capacitor. Charging of capacitor depend on T 1 =0.639*(R1 to R7)*C and Discharging of capacitor depend on T 2 =0.639(R1 to R6)*C. So final time period T=T 1 +T 2 and f=(1/T). Note that each audio tone depend on frequency and each tone have particular frequency. Press switch from s1 to s6 we are offering different current path and so that different resistance. Resistance between pin 7 and 8 maintain positive cycle of output and resistance between pin 6 and 7 maintain negative cycle of 555 timer circuit.

Working(1) We know that, T 1 =0.693*R 1 C and T 2 =0.0693*R 2 C Assume that R7=1k, So we get, R 1 =7k and R 2 ’ =6k And C=10nF, T 1 =48.51µsec and T 2 =41.58µsec And hence, T=T 1 +T 2 =90.09µsec We know that tone is proportional to frequency and frequency is inversely proportional to time f 1 =1/time =1/90.09µsec =11.10kHz So we can get different frequency by changing R 6 or pressing switch from s1 to s6, resistance will change (decrease) and results in change in frequency of sound (high-frequency)

Conclusion In the following report it was covered on the construction of the electronic piano and the tools and material needed to put together and also we have seen the function of 555 timer IC. This is very easy setup that helps you understand the soldering process and gives a confidence boost when the project come to real life

References: Engineersgarage.com Class notes and references