Unit 1 – Fundamentals

1. Electronics Unit 1 – Fundamentals

2. Electricity – study of the flow of electrons. Electronics – study of the control of electron flow. Conductor - Material w/ loosely held e-; e- flow easily (metals) Insulator - Material w/ e- tightly bound to the nucleus (nonmetals)

3. For e- to flow in a conductor there must be… 1. A difference in electric potential (voltage) b/w points. 2. A complete path (circuit)

4. Voltage (V) - Push of electrons (volts) also known as electromotive force (emf) Current (I) - Flow of electrons (amps) Resistance (R) - Restriction of electron flow (ohms, Ω) Power (P) - Electrical energy per time (watt)

5. Ohm’s Law V = I x R Twinkle twinkle little star, voltage equals I times R

6. Power Law P = I x V Power equals current times voltage Watts = amps x volts

7. Metric Prefixes Mega – 1,000,000 = 106 Kilo – 1,000 = 103 ------------- Milli – 1/1,000 = 0.001 = 10-3 Micro – 1/1,000,000 = 0.000001 = 10-6 Nano – 1/1,000,000,000 = 0.000000001 = 10-9 Pico – 10-12

8. Examples Calculate the current (in amps) in a 200 ohm resistor in a 120 Volt circuit. Express this answer in milliamps (mA).

9. Examples Calculate the current in a 100 Watt light bulb on a 120 volt circuit.

10. Examples Calculate the voltage across a 10 kilo-ohm resistor that has 0.125 amps of current through it.

11. Types of Current Direct Current (DC) Electron flow in 1 direction (cells, batteries) Conventional Current – flows from pos. to neg (Thanks Ben F.) Electron Flow – flows from neg. to pos.

12. Alternating Current (AC) Electron flow constantly changes direction at certain frequency (Hertz).

13. Schematic Symbols DC Power (Battery) AC Power Resistor

14. Cells vs. Batteries Cell - Converts chemical energy to electrical energy. AAA, AA, C, D all are rated 1.5 Volts

15. Battery - Group of 2 or more cells connected together. 9 Volt battery consists of six 1.5 cells

16. Cell & Batteries Capacity - Amount of electricity that a battery will give off before fully discharging; measured in Amp-hours. Discharge Rate - Rate at which current is drawn from battery. The capacity of a battery depends on its discharge rate.

17. Capacity @ lowest discharge rate (25 mA) 9-V 625 mAh AAA 1250 mAh AA 2850 mAh C 8350 mAh D 20500 mAh In theory, a AAA can produce 1.25 A for 1 hour. In reality, a AAA can’t produce 1.25 A.

18. Battery Capacities (Energizer) 9-Volt AA

19. ASSIGNMENT: Worksheet #1: Ohm’s Law

21. Resistors • A resistor is typically used to control the amount of current that is flowing in a circuit. • Resistance is measured in units of ohms ()

22. Resistors: Types and Package Styles Carbon Film Resistors Variable Resistors (potentiometer) 4 Bands Carbon Film Resistors Surface Mount Resistors 5 Bands

23. Resistors: Size Comparison

24. Determining A Resistor’s Value Color Code Measured Value A digital multi-meter can be used to measure the resistor’s actual resistance value. • Resistors are labeled with color bands that specify the resistor’s nominal value. • The nominal value is the resistor’s face value.

25. How To Read A Resistor’s Value Resistor Color Code

26. Resistor Value: Example #1 Example: Determine the nominal value for the resistor shown.

27. Resistor Value: Example #1 Example: Determine the nominal value for the resistor shown. • Solution: • 10 x 100  5% • 1000  5% • 1 K  5%

28. Resistor Value: Example #2 Example: Determine the nominal value for the resistor shown.

29. Resistor Value: Example #2 Example: Determine the nominal value for the resistor shown. • Solution: • 39 x 100K  5% • 3900000  5% • 3.9 M  5%

30. Resistor Value: Example #3 ? ? ? ? Example: Determine the color bands for a 1.5 K  5% resistor.

31. Resistor Value: Example #3 ? ? ? ? Example: Determine the color bands for a 1.5 K  5% resistor. • Solution: • 1.5 K  5% • 1500  5% • 15 x 100  5% • 1: Brown • 5: Green • 100: Red • 5%: Gold

32. Potentiometers – 3-terminal variable resistor Rheostat – uses the center and 1 outer terminal The resistance will be printed on it.

33. The center terminal is called the ‘wiper’ or center tap. Inside a potentiometer

34. Potentiometer Schematic Symbol Rheostat Schematic Symbol

35. Standard Resistor Values Don’t assume all the resistors in the tray are what the tray claims.

36. Resistors are normally rated for ¼ or ½ watt. For most circuits, a ¼ watt resistor will work.

37. Digital Multimeter (DMM)

38. Measuring Electrical Quantities Voltage Measure across (parallel) device Current Measure in series with device (break open circuit Resistance Measure across the device (power off!) Voltage Drop Voltage across a device

39. Types of Circuits Open No electron flow (OFF) Closed Electrons are flowing (ON) Series 1 path for electron flow. Each device receives same I, Vdrop depends on R Parallel More than 1 path for electon flow. Each path receives the same voltage. Short Electrons bypass the device.

41. Adding Resistors in Series Adding Resistors in Parallel The total resistance of a parallel circuit decreases as more resistive paths are added.

42. Series Circuit Example R1 = 100 R2 = 220 3 V 1. Calculate the total resistance of the circuit. 2. Calculate the current flowing through R1 & R2. 3. Calculate the voltage across R1 & R2. 4. How much power is used by R1 & R2?

43. Parallel Circuit Example 3 V R1 = 100 R2 = 220 1. Calculate the total resistance of the circuit. 2. Calculate the current flowing through R1 & R2. 3. Calculate the voltage across R1 & R2. 4. How much power is used by R1 & R2?

44. Voltage Drop Voltage across a device in a circuit.

45. Wire Types Solid Bare, Insulated or Enameled Stranded Insulated Cable 2 or more insulated wires bound together.

46. Wire Sizes American Wire Gauge (AWG) Indicates wire diameter (thickness). The smaller the wire, the larger the AWG number. Thick wires can safely handle more current.

47. Wire Sizes

48. Switches Switch – device placed in a circuit to open and close the circuit. Push Button Toggle Slide

49. Switches Rotary Knife Rocker Reed (Magnetic) Tilt (mercury or ball)

50. Switches