Beginners

We have written this small guide to introduce some basic contents in electronics. Here you can find some documentation about specific contents that are important to understand our emi circuits.

1.Electronic components: Resistors and Capacitors are your friends!

Electronics circuits are a set of electronic components connected by conductive ways (like wires) to complete an analog or logic function.

There are lots of different electronic components. In EMI ))) we are going to use:

- Resistors: we use it to limit current.

There are some kinds of resistors: - Fixed resistors: the most common kind of resistors. They have two pins and you can identify their value by a color code. - Variable resistors: the variable resistor is that one whose value can be adjusted by turning a shaft or sliding a control.

Links: resistors at wikipedia

- Capacitors: is an electrical device that can store energy in the electric field between a pair of closely spaced conductors. Capacitors are used in electrical circuits as energy-storage devices. They can also be used to differentiate between high-frequency and low-frequency signals and this makes them useful in electronic filters.

Links: capacitors at wikipedia

- Integrated Circuits (ICs): is a miniaturized electronic circuit (consisting mainly of semiconductor devices, as well as passive components) which has been manufactured in the surface of a thin substrate of semiconductor material.

There are some kinds of Ics:

Analog: These ICs produce, amplify or respond to variable voltages. They include amplifiers, timers, oscillators, etc.

Logic or Digital: These Ics respond to or produce signals having two voltage levels. Digital Ics include microprocessors, memories and many simple chips.

Many Ics combine analog and digital functions on a single chip.

- Sensors: A sensor is a physical device organ that detects, or senses, a signal or physical condition. Examples of sensors:

    * Microphone
    * Hydrophones
    * Seismometers
    * Photoresistor
    * Phototransistor
    * Infrared thermometer
    * RTD - Resistance Temperature Detector or Resistance Temperature Device

Links: sensors at wikipedia

2.How can I get sound sound from electronics?

Sound is the vibration of a set of particles that we are able to hear through the air or another material. Ok, but how can I do vibration with electronics? Everybody knows that in electronic music we use speakers to listen to the music. Speakers are devices that convert quick variations of voltage into sound. In fact, a speaker is not much more than an iron nucleus in front of a magnet that moves closer or not when the voltage is smaller or greater. So, If we want to listen our music we have to look for voltage vibrations (and not vibration of a set of particles).

Our mission is looking for electronic devices that create voltage variation. This variation could be caothic and we will have noise or predecible, and we could have sounds with a defined pitch.

Examples:

Example of waveforms

In the emi ))) circuits we usually use electronic timers to create defined waveforms (in fact voltage-forms). These timers offer us beautiful periodic signals:

Digital waveform

In these timers it´s usual that if you want to change the frequency of the signals you can only have to modify the voltage of one of the inputs. It makes these circuits useful and the main ingredient in a lot EMI ))) circuits!

3.Timers.

We are going to use the “555” timer (in particular NE555N or NE555P). With a 555 IC we can design circuits that sound. We are able to control the voltage forms of these timers and convert them into experimental music instruments.

The 555 is an integrated circuit (chip) implementing a variety of timer and multivibrator applications. The 555 has three operating modes:

    - Monostable mode: in this mode, the 555 functions as a "one-shot".
    - Astable mode: the 555 can operate as an oscillator. 
    - Bistable mode: the 555 can operate as a flip-flop

The connection of the pins is as follows:

- 1. GND - Ground, low level

- 2. TR - A short pulse high->low on the trigger starts the timer

- 3. Q - During a timing interval, the output stays at +VCC

- 4. R - A timing interval can be interrupted by applying a reset pulse to low (0V)

- 5. CV - Control voltage allows access to the internal voltage divider (2/3 VCC)

- 6. THR - The threshold at which the interval ends (it ends if U.thr > 2/3 VCC)

- 7. DIS - Connected to a capacitor whose discharge time will influence the timing interval

- 8. V+ - The positive supply voltage which must be between 5 and 15 V, high level

Using simply a capacitor and a resistor, the timing interval, i.e. the time during which the output stays low, can be adjusted to the need of the specific application.

Links: timer 555 at wikipedia

4.Additional Circuits

	Amplifiers
	Mixers

5. Practice tips:

5.1 Soldering - Heat the connection (not the solder) for a few seconds with the hot tip of the iron. Leave the iron in place and apply solder.

- Keep the iron´s tip clean and shinny. Wipe off debris with a damp sponge or cloth.

More info about soldering

De-soldering at the army"