1. SIXTH EDITION MALVINO Electronic PRINCIPLES

2. Introduction Chapter 1

3. Three kinds of formulas The definition: Invented for a new concept Q {defines what capacitance is} C = V {does not require verification} The law: Summarizes a relationship that exists in nature Q1Q2 f = K {verified by experiment} d2 The derivation: Obtained by manipulating other formulas using mathematics Q = CV

4. RL An ideal voltage source maintains a constant output voltage, regardless of the value of RL. VRL= 10 Volts 10 V The ideal model can be called the first approximation.

5. RL A real voltage source has a series resistance. RS VRL< 10 Volts 10 V This model is called the the second approximation. When RL is equal to or greater than 100 times RS, a real voltage source is stiff and the first approximation can be used.

6. RL An ideal current source maintains a constant output current, regardless of the value of RL. IRL= 1 Ampere 1 A The ideal model can be called the first approximation.

7. RL A real current source has a shunt resistance. RS IRL< 1 Ampere 1 A This model is called the the second approximation. When RS is equal to or greater than 100 times RL, a real current source is stiff and the first approximation can be used.

8. VTH Thevenin’s theorem can be used to replace any linear circuit with an equivalent voltage source called VTH and an equivalent resistance called RTH. 6 kW 4 kW RL 72 V RTH 3 kW Remove the load. Calculate or measure RTH. Remove the source. Calculate or measure VTH across the open terminals.

9. When working with actual circuits, please remember this guideline: The input impedance of a voltmeter should be at least 100 times greater than the Thevenin resistance to avoid loading error. DMMs are usually not a problem since they typically have an impedance of 10 MW.

10. RL 6 kW 4 kW The original circuit RL 72 V 3 kW 6 kW (RTH) The Thevenin equivalent circuit 24 V (VTH)

11. RN IN Norton’s theorem can be used to replace any linear circuit with an equivalent current source called IN and an equivalent resistance called RN. 6 kW 4 kW RL 72 V 3 kW RN is the same as RTH. Short the load to find IN.

12. RL 4 mA (IN) 6 kW (RN) 6 kW 4 kW The original circuit RL 72 V 3 kW The Norton equivalent circuit

13. RL RL 4 mA (IN) 6 kW (RN) 6 kW (RTH) A Thevenin equivalent circuit 24 V (VTH) VTH RN = RTH IN = RTH The Norton dual

14. Troubleshooting • A solder bridge between two lines effectively shorts them together. • A cold solder joint is effectively an open circuit. • An intermittent trouble is one that appears and disappears (could be a cold solder joint or a loose connection).

15. An open device • The current through it is zero. • The voltage across it is unknown. • V = zero x infinity {indeterminate}

16. A shorted device • The voltage across it is zero. • The current through it is unknown. • I = 0/0 {indeterminate}

17. A troubleshooting example: Do the two 10 W resistors form a stiff voltage divider? 10 W 100 kW 100 kW 12 V 10 W Why?

18. A troubleshooting example: What are the expected voltages in this circuit? 10 W 100 kW 100 kW 12 V 10 W

19. V A troubleshooting example: What are some causes for this voltage being too high? 10 W 100 kW 12 V 100 kW 10 W

20. V A troubleshooting example: What are some causes for this voltage being too low? 10 W 100 kW 12 V 100 kW 10 W