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ENGR 2705 - Lab #1

Title:

Basic Breadboarding

Objectives:

Provide exposure to basic breadboarding using proto boards

Theory:

This lab deals with three basic electrical quantities: voltage (V), current (I), and resistance (R). Voltage has units of volts (V), current has units of amperes (A), and resistance has units of ohms (Ω). The basic relationship between these three quantities is given by the equation

R = V/I

which defines resistance as voltage divided by current.


This lab uses two basic electric circuit laws: Kirchhoff’s current law and Kirchhoff’s voltage law. The current law states that the algebraic sum of currents into a node at any instant is zero. The voltage law states that the algebraic sum of the voltages around a loop at any instant is zero.

Parts:
  • Power Supply
  • Digital Multimeter
  • Proto Board
  • Light Emitting Diodes (2)
  • 100 Ω resistor
  • 1 kΩ resistor
  • 10 kΩ resistor
Procedure:
  1. Power connection. Turn the power supply on. Verify the +5V supply with a voltmeter (multimeter). Record the measured supply voltage. Connect the supply’s GND to a column on the board and the supply’s +5V to another column.
  2. Resistor connection. Measure the actual resistance of the 100Ω resistor. Insert one lead of the resistor (there is NOT a forward and backward difference with a resistor) to the +5V column on the proto board. Insert the other lead in an unused row or column on the board.
  3. LED connection. Insert the anode of the LED in the row or column common with the resistor lead. Insert the cathode of the LED in the GND column on the board. This will form a complete circuit with the resistor and LED in series. This means that the same amount of current flowing through the resistor flows through the LED and the voltage is split between the two.
  4. Voltage measurement. Measure the voltage across the resistor. Determine the voltage across the LED.
  5. Current calculation. Calculate the current flowing through the resistor and LED circuit. Quantify the intensity of the LED.
  6. Resistance calculation. Calculate the resistance of the LED.
  7. Repeat steps 2 - 6 for the 1kΩ resistor and the 10kΩ resistor.
  8. Plot the voltage across the LED versus the current flowing through the LED for the three configurations.
Conclusions:
  1. Discuss how well objectives were met.
  2. Discuss what you learned.