This project was created during an Instructables Build Night (in collaboration with Jameco) at Open Garage. Using a 555 timer chip, a couple of synths were created, using different capacitor and resistor values. The project uses a variable resistor to change the synth pitch.

Step 1: Build the Basic Circuit

This circuit is heavily inspired by Bare Conductive's 555 Noise Maker circuit.

What you'll need
555 timer chip
9V Battery
9V Battery clip
A variable resistor (eg. conductive rubber, fabric or a potentiometer)
2 Capacitors (2x 1uF will get you started)
1 Resistor (1K Ohm)
1 Piezo speaker

1 Resistor (220 Ohm)

Wire the circuit using the diagram attached. The LED was added to the circuit to see if the 555 was outputting something. Depending on the values of the capacitors and resistors, the frequency of the pulses the 555 chip generates can be too slow or too fast, resulting in pitches that fall outside of the human hearing range. The LED will visualise the pulses, just to make sure the circuit is working fine.

Step 2: Mod 1 : Conductive Rubber & Textile

A first synth was built using conductive rubber (we used this).

Specific components required:
Capacitors (1x 0.10uF, 1x 100uF)
Conductive rubber
1 Resistor (10K ohm) - depending on the length of the piece of rubber, you might need to add another resistor for a better effect.
Conductive thread

The idea of this synth was that it could be integrated in a tshirt, if you would pull the tshirt down - the pitch of the synth would change. Since the circuit is not too complex, it can be easily transferred to a tshirt using conductive thread (all you need is patience, and by the end of the project - you'll have greatly increased your sewing skills!)
For sewing the components, we used the Open Softwear PDF book, which has some very handy tips when it comes to sewing electronics.

Step 3: Mod2 : Potentiometer & Small Footprint

A second synth uses the same circuit as in the first step, using a potentiometer as an input. Turning the potentiometer increased or decreased the pitch. This synth was created as low piched synth (aka "the bass").

Specific components required:
2 Capacitors 100uF, 200uF
1 Rotary potentiometer (10K Ohm)

(Images of this one will be uploaded soon)

2 People Made This Project!


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12 Discussions


Question 11 months ago

Hi, I wondering how it would effect the circuit if you changed the value of the output capacitor. Would it make it louder?


Reply 3 years ago on Introduction

Hi there, the small blue one is a ceramic capacitor of 0.10uF. Compared to electrolytic capacitors, ceramic ones are not polarised - if you're using electrolytic ones, make sure to put them in the right way. Hope this helps!


4 years ago

this actually works really well. I tried it on a breadboard and it worked fine, but I just tried putting it on a stripboard and it wouldnt work. any hints?

3 replies

Reply 4 years ago

Hmm, odd. I only made the circuit on breadboard, I should think moving it to stripboard shouldn't cause any issue when all connections are the same.


Reply 4 years ago

I got it working again, after desoldering everything. rebuilt on a breadboard and took a few attempts to get going, but it works again and I am happy to say that I havent damaged any of the components with my rubbish soldering skills. therefore, the problem is either rogue solder joints, bad joints, or the scratched off copper under the 555 itself wasnt properly scratched off. any thoughts as to how I might go about putting it on a stripboard properly. btw, I am only 13, so solutions within my price range would be helpful. thanks!


Reply 4 years ago

and it turns out that you can run this without the 1uf capacitor


Reply 4 years ago on Introduction

If I remember correctly, increasing the resistance in the circuit caused the pitch to go down. I'm not sure what a 50k potentiometer would do, but if you try it and don't hear anything the sound is probably too low. If that is the case, try replacing the 10K resistor with something a lot lower.

In the example with the conductive rubber, my maximum resistance was about 3.5K ohm.


Reply 5 years ago on Introduction

my friend it a ceramic caps the brown round 103 is 0.01uf the 104 is 0.1uf