Practical 1: The Electronics Expedition

1. Aim/Objective

To identify, categorize, and familiarize with basic electronic active and passive components, breadboards (trainer modules), input sources (DC Power Supply, Function Generator), and measuring/display instruments (Digital Multimeter, CRO/DSO).

2. Apparatus/Components Required

1. Passive Components: Assorted Resistors (Carbon film), Capacitors (Ceramic disk, Electrolytic), Inductors, Transformers.
2. Active Components: Diodes (1N4007), Zener Diodes, Transistors (BJT BC547), Integrated Circuits (e.g., 555 Timer, 7400 series).
3. Prototyping Hardware: Breadboard / Analog-Digital Trainer Kit, Connecting wires (single strand).
4. Input Sources: Regulated DC Power Supply (0-30V), Function Generator (1Hz - 1MHz).
5. Measuring Instruments: Digital Multimeter (DMM), Cathode Ray Oscilloscope (CRO) or Digital Storage Oscilloscope (DSO).

3. Theory

A. Electronic Components

Components are classified into two categories:

• Passive Components: Devices that cannot introduce net energy into the circuit. They rely on a source of power.
  • Resistor (R): Opposes the flow of current. Unit: Ohm ().
  • Capacitor (C): Stores electrical energy in an electric field. Unit: Farad (F).
  • Inductor (L): Stores electrical energy in a magnetic field. Unit: Henry (H).
• Active Components: Devices capable of amplifying signals or switching currents. They require an external source to operate.
  • Diode: Allows current to flow in only one direction (rectification).
  • Transistor: A semiconductor device used to amplify or switch electrical signals and power.
  • Integrated Circuit (IC): A set of electronic circuits on one small flat piece (or "chip") of semiconductor material.

B. Resistor Color Coding

Carbon film resistors use color bands to indicate their resistance value.

• 4-Band System: Band 1 (1st Digit), Band 2 (2nd Digit), Band 3 (Multiplier), Band 4 (Tolerance).
• Formula:

C. The Breadboard (Prototyping Board)

A breadboard is used for building temporary circuits. It consists of:

• Bus Strips: Located on the sides, usually used for power supply connections. All holes in a vertical column are connected internally.
• Terminal Strips: Located in the center. Holes are connected horizontally in rows of five. A central ravine separates the two sides, sized to fit ICs.

4. Input Sources and Display Devices Setup

A. Digital Multimeter (DMM)

A DMM is a versatile instrument used to measure Voltage (AC/DC), Current (AC/DC), Resistance, and Continuity.

• Voltmeter Mode: Connect in Parallel with the component.
• Ammeter Mode: Connect in Series with the circuit path.

B. Cathode Ray Oscilloscope (CRO) / DSO

Used to observe the change of an electrical signal over time (Voltage vs. Time).

• X-axis: Represents Time (Time/Div knob).
• Y-axis: Represents Voltage/Amplitude (Volts/Div knob).

5. Procedure

Part A: Identification and Reading of Resistors

1. Select 5 different resistors from the assortment.
2. Observe the color bands on each resistor.
3. Calculate the theoretical resistance using the color code chart.
4. Switch the DMM to Resistance () mode.
5. Connect the multimeter probes across the resistor leads (polarity does not matter).
6. Record the measured value and calculate the percentage error.

Part B: Familiarization with Regulated Power Supply (RPS)

1. Switch on the Regulated DC Power Supply.
2. Set the DMM to DC Voltage () mode.
3. Connect the Red probe of the DMM to the Positive (+) terminal of the RPS and Black probe to the Negative (-) terminal.
4. Adjust the voltage knob on the RPS to set values (e.g., 5V, 10V, 12V) and verify the reading on the DMM.

Part C: Familiarization with Function Generator and CRO

1. Switch on the Function Generator and CRO.
2. Connect the output of the Function Generator to Channel 1 of the CRO using a BNC probe.
3. Set the Function Generator to produce a Sine Wave at 1 kHz frequency.
4. Press Autoset (on DSO) or adjust Volts/Div and Time/Div knobs (on Analog CRO) until a stable wave is visible.
5. Observe the waveform. Change the wave type to Square and Triangular and observe the change on the display.
6. Measure the Peak-to-Peak voltage () and Time Period () from the screen grid.

6. Observations and Tables

Table 1: Resistor Color Code Verification

Table 2: DC Source Verification

7. Calculations

Percentage Error Calculation for Resistors:

Example Calculation:
If and :

8. Result

1. Various electronic components (Resistors, Capacitors, Inductors, Diodes, Transistors) were identified successfully.
2. Resistance values were calculated using color codes and verified using a Digital Multimeter.
3. The breadboard internal connections were studied and understood.
4. Input sources (DC Supply, Function Generator) and output devices (DMM, CRO) were successfully operated and verified.

9. Viva Questions

1. What is the difference between active and passive components?
   • Ans: Passive components (R, L, C) dissipate or store energy but cannot generate or amplify it. Active components (Transistors, Op-Amps) can amplify signals and require an external power source.
2. Why do we use a breadboard?
   • Ans: It allows for temporary prototyping and testing of circuits without soldering, making it easy to modify connections.
3. What is the tolerance of a Gold band resistor?
   • Ans: .
4. How is an Ammeter connected in a circuit and why?
   • Ans: An ammeter is connected in series because current remains the same in a series circuit, and the ammeter has very low internal resistance to avoid affecting the circuit.
5. What does 'CRO' stand for and what does it measure?
   • Ans: Cathode Ray Oscilloscope. It visualizes voltage amplitude with respect to time.
6. What is the function of a Diode?
   • Ans: A diode allows current to flow in only one direction (forward bias) and blocks it in the reverse direction.
7. Identify the pins of a BJT (Transistor).
   • Ans: Emitter (E), Base (B), and Collector (C).