To familiarize with the equipment used in the Digital Logic Design Lab, including multimeters, breadboards and digital logic trainers. To understand their basic operation and applications.
Multimeter
Breadboard
Digital logic trainer
Resistors
LEDs
Jumper wires
The Digital Logic Design Lab introduces students to practical concepts of digital electronics through hands-on experiments. This lab manual focuses on the primary tools used extensively in the lab: multimeters, breadboards and the digital trainers.
A multimeter is a basic tool for measuring electrical quantities such as voltage, current, and resistance. Modern multimeters also include features for testing continuity, diodes, and frequency. It comes in two versions:
Digital Multimeter (DMM): Displays readings on an LCD screen.
Analog Multimeter: Uses a needle and scale for measurements.
Voltage measurement (DC/AC)
Current measurement (DC/AC)
Resistance measurement
Continuity test
Diode test
Turn the multimeter knob to the desired measurement mode.
Connect the probes to the appropriate multimeter terminals. (COM for the black probe and V/Ω for the red probe).
Measure the circuit parameter by connecting the probes to the circuit.
Record the reading displayed on the screen or scale.
Ensure HOLD button is not pressed while recording measurement.
While not in use, power off the multimeter to save battery.
In this lab we will not use current measurement. Therefore never insert multimeter probe in current measurement terminal. Also do not move selector switch to current measurement selection.
Handle the multimeter carefully.
A breadboard is a reusable platform for prototyping electronic circuits without soldering. It consists of interconnected rows and columns of sockets for quick assembly and testing of circuits.
Rows for horizontal and vertical connections.
Power rails for providing power and ground to the circuit.
Holes designed to fit standard component leads and wires.
Basic Breadboard Layout:
The central area is used for connecting components and building circuits.
The two side strips (power rails) are used for connecting the power supply.
Familiarize with Breadboard Layout:
Observe the breadboard and note the distinct sections
Identify the rows and columns where connections may exist.
Check Continuity of Horizontal Rows (Terminal Strips):
Insert one probe of the multimeter into a hole in a horizontal row of the terminal strip.
Insert the other probe into a different hole in the same row.
Listen for the continuity beep or observe the multimeter display.
If there is a beep, the holes are internally connected.
If there is no beep, the holes are not connected.
Check Continuity of Vertical Power Rails:
Place one probe in a hole of a vertical power rail.
Place the other probe in another hole of the same rail, further down the board.
Confirm continuity through a beep or the multimeter reading.
Test Connections Across Gaps:
Test the continuity across gaps (e.g., the middle divider of the breadboard).
Confirm that rows on either side of the gap are not internally connected.
Document Findings:
Note which rows and columns are internally connected.
Create a wiring map of the breadboard for reference in future experiments.
Verify Results:
Repeat the procedure for a few random rows and power rails to ensure consistency.
The digital trainer is an instrument panel that provides a convenient setup for building and testing digital circuits. It includes onboard features such as power supply, LEDs, and switches.
Key Components:
Onboard Power Supply:
Provides regulated 5V DC voltage for powering circuits.
Adjustable voltage levels (e.g., 5V, -12V, +12V).
LEDs (Light Emitting Diodes):
Used as indicators in digital circuits.
Connected via onboard pins with resistors to limit current.
Switches:
Act as digital inputs to the circuit.
Toggle between HIGH (1) and LOW (0) states.
Logic Probe and Clock Generator:
Logic probe to test logic states (HIGH/LOW) at various points.
Clock generator for timing and synchronization in sequential circuits.
Ensure proper connections between the trainer and external components.
Double-check voltage levels before powering up the circuit.
Use LEDs and switches for interactive testing and troubleshooting.
Assembling a Simple LED Circuit on a Breadboard
Place an LED and a resistor on the breadboard.
Connect the positive terminal of the power supply to one end of the resistor and the other end to the LED’s anode.
Connect the cathode of the LED to the ground.
Power the circuit and observe the LED glowing.
Record the multimeter voltages reading across all the components in the circuit.
Note any challenges faced during circuit assembly and testing.
Ensure proper polarity while connecting components.
Verify connections before powering the circuit.
Ensure polarity of LED and polarity of power supply are consistent.
Handle the multimeter and breadboard carefully.
This experiment provides an understanding of the basic lab equipment used in digital logic design. Students gain hands-on experience in measuring electrical parameters and assembling circuits using a breadboard and multimeter.
Multimeter Operation Diagram
Breadboard Layout Diagram
Common Component Pin Configurations