Advanced Design Applications Power and Energy © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications Teacher Resource Learning Cycle 2

The BIG Idea  Big Idea: Energy and Power are technologies that are necessary to use in the designed world. Understanding how electric circuits operate will allow users to manipulate and control the energy and power. © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Electronics Introduction © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Types of Components Active Batteries Transistors Vacuum tubes Amplifiers Generators Supply or control electric energy within a circuit. Passive Resistors Capacitors Inductors Amplifiers Generators Do not introduce electric energy into a circuit, but either store or dissipate existing electric energy. © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Electric versus Electronic What is the difference? An electronic circuit contains at least one transistor or tube. Devices which contain electronic circuits (TVs, radios, iPods) are electronic. Electric motors are never electronic because they do not contain transistors or tubes. Most motor control circuits are electronic because they contain transistors or tubes. © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Charge Bipolar – electrical effects are described in terms of positive and negative charges Unit is the coulomb (C) Charges exist in discrete quantities, which are multiples of the electronic charge ( x 10^-19 C) Basic Circuit Variables © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Basic Circuit Variables Voltage An electrical force created by the separation of charge Measured in volts (V) V Symbol: V © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Basic Circuit Variables Current An electric fluid that is created by the motion of charge Measured in Amps (A) I Symbol: I © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Basic Circuit Variables Power Energy per unit of time Measured in watts (W) P Symbol: P Algebraic sign for power: If P>0, power is being delivered If P<0, power is being extracted © 2013 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Foundations of Technology

Analog versus Digital ANALOG – gradually increases or decreases Variable voltage when potentiometer is stopped between high and low Continuous signal DIGITAL – square waveform Voltage is HIGH (on) or LOW (off) Discrete signal © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Where are digital electronics used? Microcomputers – complex ICs, microprocessors Calculators Robots Notebooks (laptops) Timepieces (watches or clocks) Music equipment Automobiles  IC Test equipment – Digital capacitance meter Frequency counters Most modern electronics equipment contain analog and digital circuitry © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Why use digital circuits? Required when data Must be stored Used for calculations Displayed as numbers or letters © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Advantages of Digital Systems 1. Inexpensive ICs can be used with few external components. 2. Information can be stored for short periods of time, or indefinitely. 3. Data can be used for precise calculations. 4. These systems can be designed more easily using compatible digital logic families. 5. These systems can be programmed and show some manner of intelligence. © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Limitations of Digital Systems 1. Most real-world events are analog in nature. 2. Analog processing is usually simpler and faster. © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Resistors... What is a resistor? It uses the concept of resistance. This is defined as the capacity of materials to impede the flow of current (or the flow of electric charge) Measured in Ohms – Ω R Symbol: R © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Resistors Resistors are noted by resistance… There are many different sizes and shapes of resistors. The larger the physical size of the resistor, the larger the power rating. Precision-type resistors consist of a thin wire wrapped around a ceramic core and covered with a ceramic coating. Standard marking methods are used Color codes are the basis © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

A Resistor Retrieved from on August 4,

Resistor Color Chart © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

How to Use the Color Chart for Resistors 1. Position the resistor so that the tolerance band is on the right. There is a large space between the tolerance band and the other bands. In some cases, there may not be a tolerance band. You should still make sure that this side of the resistor is on the right. © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Using the Resistor Color Chart 2. Identify the first band and look it up in the resistor color code chart (1st BAND column). Write down the number associated with that color. 3. Now read in order, from left to right, the second color band. Look it up in the resistor color code chart (2nd BAND column). Write down the number associated with that color. © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Using the Resistor Color Chart continued 4. Read the third resistor color band, which corresponds to the 3rd BAND column in the chart. Write down the value found. 5. The fourth color band is the multiplier. Again, look that color up in the resistor color coding chart and multiply the value written so far with the one from the resistor color chart in the multiplier column. © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Using the Resistor Color Chart continued 6. The last resistor color band corresponds to the tolerance. Simply look up the color printed on the resistor for the tolerance band in the resistor color code chart and write it down. © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Using the Resistor Color Chart Special Notes If the resistor has one more band past the tolerance band it is a quality band. Read the corresponding color number from the 1st BAND column. It is specified as the “% Failure rate per 1000 hour.” This is rated assuming full wattage being applied to the resistors. To improve the failure rates resistors are typically required having twice the needed wattage dissipation that the circuit they are used in produces. © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Using the Resistor Color Chart Special Notes In some cases, there may be four color bands, including the tolerance band. In this case, the third band is the multiplier band. When the multiplier band is gold, the resistor value is between 1 and 10 ohms. Use a multiplication factor of 0.1 to the first two digits. © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Using the Resistor Color Chart Special Notes When the multiplier band is silver, the resistor value is less than 1 ohm. Use a multiplication factor of 0.01 to the first two digits. Resistors of 5, 10, and 20% tolerance are typically made from carbon. These types of resistors are basically used to limit current flow in a circuit. © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Let’s try an example... We will use file LC2.3 Now let’s practice... We will use file LC2.4 © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Ohm’s Law Used to calculate current flow, voltage, or resistance (with the other two values known). V = I R Let’s try an example… © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Kirchhoff’s Current Law The algebraic sum of currents entering and leaving any point in a circuit must equal zero. In other words: No matter how many paths exist into and out of a single point, all the current entering the point must equal the current leaving the point. © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Kirchhoff’s Voltage Law The algebraic sum of the voltages around any closed path is zero. In other words: The voltage drops around any closed loop must equal the applied voltages. © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Resistors in Series Series: when the circuit follows a single path The series resistors can be simplified into one resistor value for a closed loop. They are simply added together. R eq = R 1 + R 2 + R 3 + … + R n © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Series Resistor Example If R1 = 8 Ω, R2 = 10 Ω, and R3 = 14 Ω, what is Req? Draw a simplified circuit. If a 12V battery is being used, what is the current through each resistor? © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Resistors in Parallel Parallel: when the circuit has several branches Again, the parallel resistors can be simplified into a single resistor value to simplify the circuit. R eq = 1 / (1/R 1 + 1/R 2 + 1/R 3 …) © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Parallel Resistor Example If R 1 = 8 Ω, R 2 = 8 Ω, and R 3 = 4 Ω, what is R eq ? Draw a simplified circuit. If a 10V battery is being used, what is the total current through the circuit? What are the currents through each branch? © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

2 Resistors in Parallel Using the relationship previously examined for parallel resistors, a short formula can be derived for 2 resistors in parallel. 1/R eq = 1/R 1 + 1/R 2 Using fractional math, we simplify to: 1/R eq = (R 2 + R 1 )/R 1 R 2 The last step in simplifying is reciprocating the equation: R eq = R 1 R 2 /(R 1 + R 2 ) © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications

Power Equations Now that we have examined current, voltage, and resistance in detail, we can use a couple of different equations to calculate power: V I = P P = V 2 /R © 2014 International Technology and Engineering Educators Association STEM  Center for Teaching and Learning™ Advanced Design Applications