Media Theory & Practice BASIC ELECTRONICS BASIC ELECTRONICS David Williams & Michael Shiloh © 2003 MakingThings LLC Media Theory & Practice BASIC ELECTRONICS OVERVIEW Session 1 Electricity is kind of like water The Components Inside Session 2 The Binary Miracle Switches can do all that? Arrange them just right, and you have a computer The computer does what you say millions of times a second Reconnecting to the real world Media Theory & Practice BASIC ELECTRONICS ELECTRICITY IS LIKE WATER Media Theory & Practice BASIC ELECTRONICS LEVELS OF UNDERSTANDING How much do you need to know? To own a car you do not need to understand the details of internal combustion engines, but the details leak out : gasoline, oil, batteries To do electronics you don't need a degree in materials science or solid state physics, but the details sometimes leak out : voltage, current, Ohms Law, etc. This session and the next are what we think you'll need to know to begin to have an intuitive grasp over the field of electronics. Media Theory & Practice BASIC ELECTRONICS ELECTRICITY Think of electricity flowing like water in a pipe The analogy to water is not perfect, but it helps. Electrons are present and quite moveable in every conductor. Electricity is the ordered flow of electrons in a conductor. Media Theory & Practice BASIC ELECTRONICS VOLTAGE AND CURRENT Voltage is like water pressure Measured in Volts, V Current is like water volume Measured in Amps, A 1/1000th of an Amp is a milliamp – mA Power is Voltage x Current Measured in Watts, W 1/1000th of a Watt is a milliwatt ­ mW Media Theory & Practice BASIC ELECTRONICS RESISTANCE Almost everything that conducts electricity has a resistance. It doesn’t conduct it perfectly. Resistance is measured in Ohms (Ω) 1000Ω = 1kΩ 1,000,000Ω = 1MΩ Media Theory & Practice BASIC ELECTRONICS OHMS LAW Relates Voltage and Current in a simple circuit V=IR Volts = Current (I) x Resistance (R) (this means I = V / R and R = V / I ) Media Theory & Practice BASIC ELECTRONICS CIRCUITS – WATER AND ELECTRICITY A circuit needs a complete path, and a source of energy Electricity, like water, flows only when it can. Media Theory & Practice BASIC ELECTRONICS CIRCUIT DIAGRAMS I Circuit Diagrams (also called Schematics) are a compact easy way to represent circuits. Only the essential details are represented. Like the London Underground – drawn for human use Media Theory & Practice BASIC ELECTRONICS CIRCUIT DIAGRAMS II More realistic diagram Vcc & Gnd Connections Many paths Chip (LM555) Resistors, Capacitors Non­literal line connections Optional parts Media Theory & Practice BASIC ELECTRONICS PRINTED CIRCUIT BOARDS When wiring­up circuits with wires is too much work Each trace (thin strip of copper) replaces one wire Media Theory & Practice BASIC ELECTRONICS DEMONSTRATION ­ CIRCUITS Objectives Show a simple circuit Measure voltages & current Materials Battery and Lamp Multimeter Media Theory & Practice BASIC ELECTRONICS COMPONENTS The components that make up a circuit Media Theory & Practice BASIC ELECTRONICS CONDUCTORS Connections are very important Many things are conductive – car chassis / salty water Stranded vs. Solid Core Solid core is much more likely to break when flexed AWG (American Wire Gauge) Standard AWG 16 – Larger Power Connections AWG 18 – Power Connections AWG 22 – Good Interconnection Size AWG 30 – Very fine – breaks easily Media Theory & Practice BASIC ELECTRONICS CELLS & BATTERIES Chemical Reactions creating electricity Lead­acid (car battery approx 2V) Alkaline (regular cells approx 1.5V) Lithium Ion (latest rechargeable approx 3.6V) Fuel Cells (new technology) Solar Cells (light converted into electricity) Fruit! (lemons with copper and zinc electrodes) Can put them in series (end to end) to increase voltage Can put them in parallel (side by side) to increase current Media Theory & Practice BASIC ELECTRONICS POWER SUPPLIES Connect to 110V AC to provide electricity in a different form. Be very careful with 110V! It can kill you. Anything over 50V is dangerous. Media Theory & Practice BASIC ELECTRONICS SWITCHES AND PUSH BUTTONS Connect and disconnect circuits Media Theory & Practice BASIC ELECTRONICS RESISTORS As the name suggests ­ tend to present a partial barrier to electricity flow Recall, Resistance is measured in Ohms (Ω) 1000Ω = 1kΩ 1,000,000Ω = 1MΩ Also need to note rated power (e.g. 1/8W, 5W) Media Theory & Practice BASIC ELECTRONICS POTENTIOMETERS Variable Resistors Have a resistance that varies according to the mechanical position of one of its wiper. Media Theory & Practice BASIC ELECTRONICS LIGHT EMITTING DIODES (LEDs) Tiny light sources – come in a variety of colors Require very small current – but will take all you offer – always use a resistor! Values between 300Ω and 1KΩ are useful. Media Theory & Practice BASIC ELECTRONICS DEMONSTRATION ­ LEDs Objectives Show how to use an LED Show how it only works one way round Show how you need a resistor Show how different resistors give different brightnesses, potentiometers Materials Soldering iron / solder / wire LED Resistor / Potentiometer Media Theory & Practice BASIC ELECTRONICS CAPACITORS As the name suggests ­ tend to store electricity ­ like a mini­battery Measured in Farads (F) 0.000001F = 1µF 0.000000001 = 1pF Also need to note rated voltage Charging Charge d Discharging Media Theory & Practice BASIC ELECTRONICS DEMONSTRATION ­ CAPACITORS Objectives To show charging and discharging capacitors Show charge with LED / resistor Show discharge with LED / resistor Materials Capacitor (large value) 2 x Resistor / LED combo Soldering Iron, Solder Media Theory & Practice BASIC ELECTRONICS DIODES Family of components which only let electricity flow one way Many different kinds – each with different characteristics Main characteristic to note is power (W) Media Theory & Practice BASIC ELECTRONICS DEMONSTRATION ­ DIODES Objectives To show diodes blocking current Materials Power supply Diode 12V Lamp Solder / Soldering Iron Media Theory & Practice BASIC ELECTRONICS SOLENOIDS Electromagnets Current is passed through the coil and a magnetic field is created Used to release latches, lock parts in place, etc. Media Theory & Practice BASIC ELECTRONICS MOTORS Family of components that use sequenced electricity and magnetism to make movement Voltage, Current, Torque & RPM often specified Media Theory & Practice BASIC ELECTRONICS RELAYS Electromechanical Switches – Apply a current to the coil and the connected switches are connected and disconnected. Cars use relays to switch 12V, 500A! Silicon Relays also available with no moving parts Media Theory & Practice BASIC ELECTRONICS DEMONSTRATION SOLENOIDS / MOTORS / RELAYS Objectives To show solenoids, motors and relays running Materials Solenoid / Motor / Relay Power Supply Media Theory & Practice BASIC ELECTRONICS VOLTAGE DIVIDERS I Simple and vital part of electronics. Used throughout electronics. Vital in the connection of sensors to computers. Take a resistor and connect it to a power source. The voltage on one side is 5V, and on the other is 0V What would it be in the middle of the resistor? Media Theory & Practice BASIC ELECTRONICS VOLTAGE DIVIDERS II Can set this up: Take two resistors of equal value in series and connect them to a power source. We can guess that the voltage at p is 2.5V if ra = rb. Each resistor does half the work. Media Theory & Practice VOLTAGE DIVIDERS III And to extend this further: What if the resistors are not the same? We can guess that the voltage at p will be greater than 2.5V if ra < rb. Less resistance => less voltage drop BASIC ELECTRONICS Media Theory & Practice VOLTAGE DIVIDERS IV Now we have something useful What if we substitute one of the resistors for a resistive sensor of some kind? We can guess that the voltage at p will be dependent on the quality sensed. BASIC ELECTRONICS Media Theory & Practice BASIC ELECTRONICS VOLTAGE DIVIDERS V Variable Resistors can work like this too With this circuit, we can sense the rotational position of a shaft or a linear position The voltage at p will be dependent on the position of the wiper. Media Theory & Practice BASIC ELECTRONICS DEMONSTRATION – VOLTAGE DIVIDERS Objectives To mirror the foregoing voltage divider discussion with voltage divider examples Materials Multimeter Soldering Iron and Solder Resistors Resistive Sensors (Bend / Light) Media Theory & Practice BASIC ELECTRONICS TRANSISTORS I Developed to switch and amplify Come in a large number of different varieties, shapes and sizes Media Theory & Practice BASIC ELECTRONICS TRANSISTORS II MOSFETs are transistors that make very good switches A very small signal on the gate can switch very large loads on and off thousands of times a second. Media Theory & Practice BASIC ELECTRONICS DEMONSTRATION – TRANSISTORS Objectives To show the operation of a transistor Materials Multimeter Soldering Iron and Solder Motor / Halogen Big MOSFET MOSFET datasheet Media Theory & Practice BASIC ELECTRONICS BINARY The gateway to digital electronics Media Theory & Practice BASIC ELECTRONICS THE DECIMAL NUMBER SYSTEM At the risk of stating the obvious… We count by going through our list of number symbols until we run out… 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, … When we run out, we mark that fact with a digit in another column and start again … 8, 9, 10, 11, 12, 13, 14, 15, … When we run out again, we use another column … 98, 99, 100, 101, 102, 103, … Media Theory & Practice BASIC ELECTRONICS THE BINARY NUMBER SYSTEM Binary is identical, except we only have 0 and 1 We count by going through our list of number symbols until we run out… 0, 1, … When we run out, we mark that fact with a digit in another column and start again … 0, 1, 10, … When we run out again, we use another column … 10, 11, 100, 101, 110, 111, … Media Theory & Practice BASIC ELECTRONICS JUST LIKE A REAL NUMBERING SYSTEM You can convert to decimal, since you know how big each column is – 32, 16, 8, 4, 2, 1 11002 = 1 x 8 + 1 x 4 + 0 x 2 + 0 x 1 = 1210 You can add and subtract binary numbers (and all other arithmetical operations) 0010 1000 + 0110 ­ 0110 1000 0010 Each column is called a bit. Eight bits are called a byte. Media Theory & Practice BASIC ELECTRONICS THE BIG STEP So what’s so cool about a numbering system that only has 2 digits? Each digit can be unambiguously represented by a voltage on a wire. And you can do whatever you want with it. Media Theory & Practice BASIC ELECTRONICS 83 What is 8310 or 010100112? Media Theory & Practice BASIC ELECTRONICS MATERIALS Media Theory & Practice BASIC ELECTRONICS Materials Power Supply 1.5V Cell Wire Solder Soldering Iron LEDs Resistors (1K & 500Ω) Potentiometer Diodes (high­ish current) Bend Sensor Photocell Bend sensor MOSFET & Datasheet Motors Halogens