555 Pocket Keyboard




Hello every body, this is a 555 timer-musical-keyboard project, with exact sounds of the key, i saw a project here...


but in this project, the keys don't give exact notes, so i designed a few things, added a few potentiometers to the circuit which helps to adjust to the exact notes you have in a normal keyboard...

You can see that the sound created by the keyboard is quite nice, and try to recognize the song i played in the video...

Before You start making this project, you should know the basic electronics properties, equipment and should know how to solder/making circuits...

Because i will not show the making of the circuit in detail, just the circuit diagram, or if you are too lazy to build the project on a perfboard like i did, i have also given the PCB design on an eagle file, you can re-check the design, because i haven't added small things like on/off button in the design, you can add it as per your requirements...

So here comes the 1st step to build this 555 based keyboard...

Step 1: Components

The basic components required to build the keyboard are :

-555 Timer

-100k (or heigher) Potentiometer

-4k7 (or lower) Potentiometer

-10k Potentiometer

- 2.2k resistors {12 peices}

-4.7k resistor

-8 Ohm Speaker

-two-way slide switch

-an LED + 470E resistor

-14 micro switch

-100nF capacitor

-10uF capacitor

-9v Battery (with connector)

-perfboard (10cm by 15cm)

Other extra components which i have used -

-Male + Female stereo Connectors [to connect the board with the Spearker]

-Glue [to stick the speaker and the battery on the board]

Step 2: Breadboarding

In this step, you must see if you have all the components with you and you can do all the connections correctly, i wil not tell you about breadboarding in detail, you can google it, or you can just look it from this link

[This picture in this step, of the breadboarded circuit, is taken from this link]


i have uploaded the circuit diagram with the breadboarded circuit, you can check out the detail of bredboarding this project from the link above...

This is just to make sure that you are comfortable with the circuit, plus breadboarding doesnt take too much of your time, you can just put up 4-5 micro switches to check the working, no need of using all 14 swtiches in the breadboard... as you ll have to take them out while building the circuit...

Step 3: Component Placement - Planning

As you can see, that i have used a big board, just so that i can have my speaker and the battery on the board...

Plus i have placed the switches with wide gap, so that only 1 button should get pushed with my finger, not more...

You can make your board however you want, you just have to be sure that you havent made any changes in the circuit...

You can use any smaller speaker, any buzzer...

or you can just use the eagle circuit board design and design your PCB yo

Step 4: Solder Your Components

You can make the circuit in the following sequence :

1- fix the keys

2-add resistors to the keys

3-fix the 555

4-build circuit around 555

5-connect the 555 with the keys

6-connect the speaker

7-connect the batter lead

8-check all the connections once again

9-join the battery and check the working

Step 5: Tune It and Play It

You can use a case for your keyboard, which will protect it, i didnt want to use the case because in this prefboard, there is a lot of space in the sided to hold the pcb without touching the circuit, so i skipped that part...

Now when you are prepared with your circuit, you might want to tune it first, the 100k potentiometer can be adjusted in such a way that the last 9 micro switch, or i should say that higher pitch keys [close to the 100k potentiometer] must sound synchronized, and then the 10th and 11th can be tuned with 10k potentiometer after tuning those 9 keys, after tuning them, you can tune the 12-13-14th keys with the second 10k pot.

Now you are ready to play your own made KEYBOARD...

If you have any other questions, then you are welcome to ask them here...

Thank you...! enjoy...

2 People Made This Project!


  • Trash to Treasure

    Trash to Treasure
  • Tape Contest

    Tape Contest
  • Arduino Contest 2019

    Arduino Contest 2019

44 Discussions


1 year ago

how 555timer ic works??


3 years ago

great project

can i place your project on my website.

i'm working on a website which is related to electrical projects.

i also mention your name, link and other info.

plz reply

1 reply

Reply 3 years ago

yes you can easily add more keys, the best way to do that will be, you should first try the circuit with extended keys on bread board. you can try the different placements of the potentiometer between the keys.
if the result is not satisfactory then you can change the resistance easily in the bread board easily.

Tanmay Deuskar

3 years ago

Hello, one quick question ...
Do I need to connect threshold to trigger? In the diagram it looks like it is connected, but I just to be sure.


1 reply

555 is used here to generate continuous square wave. By changing the resistance value across two pins of the IC, we can change the frequency of the wave, this is how we get different sounds in this project.


4 years ago

Ok thx


4 years ago

Another question I'm confused about the schematic for all the pots do u use all 3 pins on all the pots?

1 reply

Reply 4 years ago on Introduction

yes, although this work can be done using just 2 pins of the potentiometers [middle pin and any other one ], but as shown in schematic, 2 pins of the potientiometer is connected with each other [middle and the right pin], hence technically, all the 3 pins are used...but logically we made 2 pins out of 1 potentiometer...

you can connect the pot in the opposite way also, by connecting the middle pin with the left pin, it wont make any change, just the resistence will increase/decrease in the other direction as it would have been effected with the previous connections.

i hope you understood the point?


4 years ago



4 years ago

I building this project and I found all the parts except the 100 nf cap can I use a .1 uf cap instead?

1 reply

Reply 4 years ago on Introduction

these both values are same, so you can use 0.1uF in place of 100nF capacitor...