Electronics Production – The Basics

The differences between electrical and electronic devices:

Electrical devices are powered by electricity (e.g. lights, kettle, fridge, toaster). Electronic devices use electrons in a clever way (e.g. to control a robot or a display like a TV).

The basic principles: 

To understand electronics and circuits it is imperative to understand the relationship between Voltage, Current and Resistance. This relationship is defined as Ohm’s law: Voltage (Volts) = Current (Amps) x Resistance (Ohms)

V = I x R

Second it is important to know how Power relates to Ohm’s law: Power (Watts) = Current (Amps) x Voltage (Ohms)

P = I x V

Circuits:

There are 2 types of circuits that determine how the components are arranged:

Signals/Waves:

There are two types of electronic signals:

• Analog waves are smooth and continuous (e.g can vary anywhere between 0-1)
• Digital waves are stepping, square, and discrete (e.g. are either 0-off, or 1-on).

It is possible to represent an analog signal digitally with PWM (pulse width modulation). This simply turns the signal ON and OFF in different amount to give an overall average percentage ON (voltage output).

Components:

• breadboards – allow you to connect items up without solder  – not very robust Here’s a good guide to using breadboards.
• veriboard – allows you to connect items with solder – much more robust
• PCB – typically printed, etched, machined boards which connect components with solder – and tend to be much smaller than the above.
• wires – conduct electricity (larger diameter = can take more current)
• resistors – resist flow of electricity, here’s a resistor colour chart and calculator
• potentiometers – are resistors where the user can vary the resistance
• capacitors – store energy (kind of like a battery) in an electric field. They store charge and tend to smooth out changes in current.
• inductors – probably won’t need these just yet, but an inductor stores energy in a magnetic field when electric current flows through it.
• buttons – like switches, but only make connection when pressing
• switches – allow toggling between open circuit (no flow + no activity), and closed circuit (flow + activity)
• diodes – only allow current to flow in one direction (where the arrow is pointing). Note that LEDs are Light Emitting Diodes – they are a type of diode.
• batteries – provide voltage potential  –  i.e. they store energy (typically are 1.2, 1.5, 3, 3.7, 9, 12.6V)

Input devices and Output devices:

Input devices allow the input information to a circuit. They can also be sensors, because typically they sense something in the environment (e.g. temperature, humidity, light) and quantify how much of it there is in some way (e.g. temperature in Degrees Celcius, humidity as a % and light as light intensity or Lux). Some examples of input devices you can use in circuits are:

• temperature: thermistor, thermocouple
• light: LDR (light dependent resistor), or photodiode (more accurate)
• distance: sonar sensor

And many others, e.g. magnetic field, acceleration, sound level, vibration, force, pressure, angle, image.

Some sensors are passive and can simply be plugged in and they change resistance with a change in property (e.g. LDR resistance changes as you change the amount of light). Other sensors are active which means they require their own circuit and power source.

Output devices do something. These can be motors (DC, brushless DC, servo, stepper), lights, speakers, solenoids, displays. Note. output devices sometimes need special drivers to make them work, and often the require quite a lot of power to operate, a separate power source may be required.