First day, first experiences…

30 October 2007 at 9:36 pm (Circuit Bending Workshop, Mechatronics, School of Art)

We started the workshop making simple experiences with sound.

Workshop Bending - Day 1

The first experience was to use a speaker, wires and a 9V battery to generate sound, thanks to feedback. We take two wires, we put one of theme on the speaker’s membrane and we approach the second wire in order to make contact. Surprise: we generate a sound that is specific to that particular speaker (it works on all speakers). What happens is that the speaker’s membrane vibrates making the contact go on and off witch produces the frequency we can hear.

Workshop Bending - Day 1

Ok… This was sweet and easy… And what if we take the two wires and we “taste” the materials around us? So we started to play with materials fixing one wire and scratching the second on it. The result is some strange sounds. The material’s asperity (more or less visible) makes the scratched wire to close and open the circuit, generating frequencies that we can hear.

Ok, so with a battery, some wires, a cheap and old speaker, we can actually make sounds… Hum… Interesting… No amps, no expensive and complicated electronics… Ok… But let’s try to put some electronics on it…

The speakers and microphones are built the same way… The main difference is that they are originally built for a specific function (to generate sound from an analogical signal; to generate an analogical signal from a sound). “Normally” you put the speaker in the output of an amplifier and the microphone in the input. But, if you put a speaker in the output and another one in the input, you will find out that the speaker plugged in the input works like… a microphone! Oh what a surprise! The main difference between a microphone and a speaker used as a microphone, besides the visual aspect, is the sound signal generated. Using different speakers as a microphone modulates the sound in different ways… And if we put the speakers in front of each other, cool sounds come out…

Workshop Bending - Day 1

Another device used to generate sound is the buzzer… The buzzer is basically a crystal that vibrates when electricity goes thought it. But, if you vibrate the crystal, you have electricity production, therefore a sound signal. So, if we put a buzzer in the input of an amplifier and a speaker in the output we should hear something…. But the buzzer only generates sounds when the crystal vibrates, and the crystal is a solid, not a membrane, so it needs more energy to vibrate. So buzzers are able to record strong vibrations (like in solids). This makes us able to record cool sounds that are produced inside materials (like ice melting).

Workshop Bending - Day 1

Like the speaker used as a microphone, you can use the buzzer and the output speaker in a feedback mode, here is an example of what you can do, basically, we taped the buzzer to the plastic glass and connected it in the input of the amplifier. The sound produced makes the glass (and the buzzer) jump and produce sound witch makes them jump, etc.

After this we discovered a nice device that reproduces the electromagnetic waves to a sound signal. The cool thing is that you can copy a signal and amplify it with no electric contact. This device was used to spy phone calls (now the armies must have more high tech devices for that… I guess…) , but you can use theme to spy all kind of electromagnetic generator devices (like a computer, or a circuit)… This device can’t be used to produce sound, only to generate signals…

The last component we saw to produce sounds as a microphone was a magnetic head. The magnetic head is able to read data on magnetic tapes or cards. The head generates an electric signal that can be converted into sound.

Workshop Bending - Day 1

Finally, we used radios to generate some strange sounds by opening theme, licking our fingers and playing with the circuits.

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