Hello, I see you wan't to know how to make an NE555 timer based 3 octave synthesizer which fits in a tin. Well, you came to the right place :)

For this project you will need:

1. 36 tactile buttons (any buttons of the same kind will work).

2. 2 perforated boards for double layer stacking.

3. 3.5mm audio jack with internal switch.

4. NE555 timer chip with socket.

5. 1k Ohm resistor.

6. 100nF and 10uF capacitors.

7. 36 x 20k Ohm trim pots

8. Lots of wire and solder.

9. A nice tin to put everything in.

10. Battery clip and 9V battery.

11. A multimeter with frequency measurement function or oscilloscope (for easier tuning).

12. Common electronics knowledge and dedication.

Optional sound output methods (you will need to chose one of these) :

1. Piezo buzzer (without external amplification sound is quite poor)

2. External speaker with built in amplifier (the best method)

3. Headphones (earbuds from phone or MP3 player will do the trick)

Step 1: Components of the Synthesizer

There are three core components of this build:

1. The upper board

2. The lower board

3. Battery clip and battery itself

Step 2: Upper Board

Upper board contains:

1. Buttons and their wiring

2. Male headers for every button and common header for connecting to pin 2 of NE555 timer.

Step 3: Lower Board

Lower board is mainly about wiring and connecting all the components. This part requires a lot of soldering and wire management skills, so I strongly do not recommend this instructable for beginners.

Once your soldering job is done it is time to tune the trim pots. It is much easier to connect a jumper wire to the common female header and tune the synth with multimeter connected to the audio jack while connecting other end of the jumper wire to each of the female button headers.

Step 4: Finishing Your Synthesizer

At this point there are some additional things you can do:

1. You can drill a 4 mm hole for your 3.5 mm audio jack.

2. Spray paint the tin or customize it as you please.

3. Add a piezo buzzer.

Also if you are interested in this you could check out Thomas Kim YouTube channel: https://www.youtube.com/user/yeosujjang and visit his webpage: http://kor.pe.kr/make/electronics/555_organ/ (it is in Korean, but Google translator does quite a nice job translating it). He is the guy who got me into this, so thanks to him :)