Electronic pianos are simple circuits that are usually seen in children’s toys & doorbells. These circuits produce a musical sound or beep on pressing a pushbutton. So, in this project, we are going to build a simple electronic piano using a 555 timer IC by following simple step-by-step instructions.
The heart of this Electronic Piano is a 555 timer operating in astable multivibrator mode. An astable multivibrator is a free-running oscillator that switches continuously between its two unstable states. With no external signal applied, the transistors alternately switch from cutoff to saturation state at a frequency that RC time constants of the coupling circuit determine. If these time constants are equal (R and C are equal) then a square wave will generate with a frequency of 1/1.4 RxC. Hence, an astable multivibrator is also a pulse generator or a square wave generator.
![](https://circuits-diy.com/wp-content/uploads/2020/08/electronic-piano-pcbway-1280x656.jpg)
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Hardware Components
The following components are required to make Electronic Piano Circuit
[inaritcle_1]NE555 Pinout
![555 timer ic pinout](https://circuits-diy.com/wp-content/uploads/2020/02/555-timer-ic-pinout-1024x583.png)
For a detailed description of pinout, dimension features, and specifications download the datasheet of 555 Timer
Electronic Piano Circuit
![electronic piano circuit](https://circuits-diy.com/wp-content/uploads/2019/04/electronic-piano-circuit-1-1024x661.png)
Steps
Make sure to follow each step as shown in the video above
1) Solder all Push buttons onto the PCB Board
![](https://circuits-diy.com/wp-content/uploads/2019/04/1-2-1184x720.jpg)
2) Cover all pushbuttons with their Caps
![](https://circuits-diy.com/wp-content/uploads/2019/04/2-2-1280x720.jpg)
3) Solder all resistors
![](https://circuits-diy.com/wp-content/uploads/2019/04/3-2-1116x720.jpg)
4) Trim any extra wiring.
![](https://circuits-diy.com/wp-content/uploads/2019/04/4-2-1280x720.jpg)
5) Solder the 500K Trimmer Pot on the PCB Board
![](https://circuits-diy.com/wp-content/uploads/2019/04/5-2-1156x720.jpg)
6) Solder all capacitors onto the PCB board
![](https://circuits-diy.com/wp-content/uploads/2019/04/6-2-1208x720.jpg)
7) Solder the 8-pin IC Jacket onto the PCB Board & Place the IC in the case
![](https://circuits-diy.com/wp-content/uploads/2019/04/7-2-1224x720.jpg)
![](https://circuits-diy.com/wp-content/uploads/2019/04/8-2-1180x720.jpg)
8) Solder the input power connectors (Battery clip) & the output speaker on the PCB Board.
![](https://circuits-diy.com/wp-content/uploads/2019/04/9-1-1280x685.jpg)
![](https://circuits-diy.com/wp-content/uploads/2019/04/10-1-1280x717.jpg)
9) Connect the 9V battery & power up the circuit
![](https://circuits-diy.com/wp-content/uploads/2019/04/11-1-1208x720.jpg)
10) test & inspect the circuit.
![](https://circuits-diy.com/wp-content/uploads/2019/04/12-1-1200x720.jpg)
Working Explanation
The working of this circuit is pretty simple, a total of 8 different switches/pushbuttons are used here to generate different tones which will be fed to the speaker on pressing. a 555 Timer IC is used here to generate tone frequencies of the audible range ( 20Hz to 20KHz ).
When the first button from the right is pressed it produces a high-pitched tone. When the last button is pressed it delivers a low-pitched tone. This is because of the resistance connected to the buttons. The low thresh hold voltage obtained at the Pin 6 slows the charging and discharging of the 10uF capacitor. As the resistance value increases, the voltage at the threshold pin decreases, and low frequency pass through the speaker.
Applications
- Usually used in small devices such as toys, doorbells & alarms, etc.