1. Introductory Electronics
Pete Beens
Westlane Secondary School
Niagara Falls
teach Computer Engineering and Electronics

2. Why is this useful? You can do the extra credit lab for pts
You may want to add a circuit to your final project
You can do additional circuit labs as an alternate project (analog, digital)
Electricity is mysterious, learning to understand it could come in handy some day!

3. Three Main Invisible Quantities
Voltage, V, Volts
Provides the “push”
Current, I, Amperes (Amps)
Flow of Electrons
Amount of Current is dependent on Voltage and Resistance
Resistance, R, Ohms (W)
Limits the amount of current
water tower analogy; height of tower is voltage, flow of water is current, tap is resistance

4. Safe Levels Voltage: 30 V Current: 5 mA (0.005 Amperes)
Voltages inside a computer do not exceed 12 V, except at the power supply and power switch, which are at 120 V. Be careful in these areas!
Current: 5 mA (0.005 Amperes)

5. Voltage Can Be Provided From…
A battery

6. Voltage Can Be Provided From…
Breadboard (trainer)
See credits -- (London)

7. Current …is simply the flow of electrons
Direction depends on convention
Electron flow is from (-) to (+) (flow of electrons)
Conventional flow is from (+) to (-) (hole flow)
check start of chapter in textbook to check for current convention; this is important and must be defined when talking about direction of current flow
refer to for an excellent description

8. Resistors – Basic Specs
Can be rated by…
Resistance (Ohms, W)
Tolerance (% of nominal value)
Power Rating (Watts)
Schematic Symbol…

9. Resistors – Types Variable (Potentiometer, Rheostat) Fixed
variable resistors used to vary voltage (volume control) or current (LED intensity)

10. Resistors – Colour Code
colour bands normally start towards one end
Reproduced by permission of Tony van Roon,

11. Resistors –Colour Code Example3
102 5%
(gold)
1st band: orange = 3
2nd band: orange = 3
3rd band: red = 2 (i.e. 102)
4th band: gold = 5%
33 x 102
= 3300 W
= 3.3 k W

12. Resistors – Typical Power Ratings

13. Ohm’s Law
“Current (I) is proportional to Voltage (V) and inversely proportional to Resistance (R)”
UNITS: 1 Volt across 1 Ohm produces 1 Amp of current

14. Calculate the current in this circuit using Ohm’s Law6V

15. Calculate the current in this circuit using Ohm’s Law6V

16. Calculate the current in this circuit using Ohm’s Law3V

17. Calculate the current in this circuit using Ohm’s Law6V

18. How Many Volts across Resistor?

19. Ohm’s Law, Including Power
Note that Power is also included in this chart
Reproduced by permission of Tony van Roon,

20. How Many Watts dissipated by Resistor?
P=I2R

21. Kirchhoff’s Law’s Kirchhoff’s Voltage Law Kirchhoff’s Current Law
“The sum of the voltage drops equals the applied voltage”, or…
“The sum of the voltage drops around a closed loop equals zero”
Used in series circuits
Kirchhoff’s Current Law
“The current entering a junction must equal the current leaving the junction”
Use in parallel circuits.

22. Series Circuits
One current path, therefore the current is the same everywhere
Total resistance is the sum of the individual resistances

23. VOLTAGE DIVIDER I

24. Calculate RT and the current in this circuit, and v1
4 W W v1 6V

25. Parallel Circuits More than one current path
Total current is the sum of the individual currents

26. Parallel Circuits (2)

27. Calculate RT and the current in each branch of this circuit
i i2
6 W W 6V

28. Calculate RT and the current in each branch of this circuit
i i2
6 W W 6V

29. Calculate RT and the current in each branch of this circuit
3 W IT
i i2 6V
6 W W

30. CAPACITORS – DC I
The capacitor charges linearly till the voltage across it reaches the applied voltage after which the driving force is lost and the capacitor ‘blocks’ DC.

31. RC CIRCUIT – DC
- VC +
This is similar but the capacitor charges non-linearly till the voltage across it reaches the applied voltage after which the driving force is lost. Time constant τ=1/RC is the time in which the capacitor is charged to 63% τ

32. RC CIRCUIT – DC
After removing the battery, it discharges if there is a resistance in the external circuit (otherwise it retains the charge : use in DRAMs). The discharge is non-linear
- VC(t) + I

33. DIODES If V > VON of diode, I I Forward bias, conducting
Reverse bias, non conducting

34. N-Type Semiconductor
P-Type Semiconductor

36. E E

38. Light Emitting Diodes A type of diode designed to emit light
Can be visible or IR
2 V voltage drop
Typically draws 20 mA (0.020 A)
Schematic Symbol…

39. A Simple LED Circuit

40. Analyzing a LED Circuit with KVL and Ohm’s Law

41. The “Fuel Tank” Circuit
1) Charge the Fuel Tank

42. The “Fuel Tank” Circuit
2) Dis-Charge the Fuel Tank

43. Lab--The Breadboard
Vin (6 V)
Vss (Ground)
Each row is
Connected

44. Lab--A Simple Circuit
Vin (6 V)
Vss (Ground)
Each row is
Connected

45. Wire the following parallel circuit on the breadboard
i i2
6 W W 6V

46. The Parallel circuit from previous
Vin (6 V)
Vss (Ground)

47. A Series Circuit
Vin (6 V)
Vss (Ground)

48. Lab--Measure Volts in Parallel
Because the voltmeter is placed in parallel with the circuit element, you do not need to physically alter your circuit in order to measure voltage.

49. Measure Voltage in Parallel
Vin (6 V)
Vss (Ground) V

50. Measure Current in Series
You must physically modify your circuit:
1.Create a gap in the segment where you want to measure current.
2. Reconnect the gap using your ammeter as a jumper wire

51. Measure Current in Series
Vin (6 V)
Vss (Ground) A

52. Caution!!!
If you measure Amps
in parallel, you can
damage the meter

53. Measure Resistance out of circuit
Select the ohms mode, remove the resistor to be measured from your circuit, and place the ohmmeter leads across the resistor leads. It is not OK to use your fingers to do this (your body resistance will change result!)

54. Web References
Learn Electronics Tutorials and Information Pages
Electronics Tutorials
Tutorials for Learning about Electronics
AC Electricity and Electronics

55. Web References Jones on Stepper Motors Holt Software Tony’s Website
Holt Software
Turing, Computer Engineering textbooks
Tony’s Website
Many excellent tutorials, example circuits
- and many others…