A Comprehensive Guide to Checking Transistors with a Digital Multimeter in Sinhala: Unraveling the Mysteries of Semiconductors

Transistors are the fundamental building blocks of modern electronics, playing a pivotal role in amplifying signals, switching circuits, and performing various other essential functions. Understanding how to check transistors with a digital multimeter (DMM) in Sinhala is crucial for troubleshooting and repairing electronic devices. This comprehensive guide will provide a step-by-step walkthrough of the process, empowering you with the knowledge to diagnose and resolve transistor-related issues.

Identifying Transistor Leads

Before testing a transistor, it’s essential to identify its three leads: the emitter (E), base (B), and collector (C). These leads are typically labeled on the transistor’s casing or can be determined using a datasheet.

Testing BJT Transistors

NPN Transistors

1. Diode Mode:

• Set the DMM to diode mode.
• Connect the positive probe to the base and the negative probe to the emitter.
• A forward voltage drop of around 0.7V should be measured.
• Repeat the test with the probes reversed. No voltage drop should be measured.

2. HFE Test:

• Set the DMM to hFE mode.
• Connect the base to the emitter and the collector to the positive probe.
• A reading of around 100-200 should be displayed.

PNP Transistors

1. Diode Mode:

• Set the DMM to diode mode.
• Connect the positive probe to the base and the negative probe to the collector.
• A forward voltage drop of around 0.7V should be measured.
• Repeat the test with the probes reversed. No voltage drop should be measured.

2. HFE Test:

• Set the DMM to hFE mode.
• Connect the base to the collector and the emitter to the positive probe.
• A reading of around 100-200 should be displayed.

Testing FET Transistors

N-Channel JFETs

1. Ohms Mode:

• Set the DMM to ohms mode.
• Connect the positive probe to the gate and the negative probe to the source.
• A high resistance (typically several megaohms) should be measured.
• Connect the positive probe to the gate and the negative probe to the drain.
• A low resistance (typically a few hundred ohms) should be measured.

P-Channel JFETs

1. Ohms Mode:

• Set the DMM to ohms mode.
• Connect the negative probe to the gate and the positive probe to the source.
• A high resistance (typically several megaohms) should be measured.
• Connect the negative probe to the gate and the positive probe to the drain.
• A low resistance (typically a few hundred ohms) should be measured.

Interpreting Test Results

• Diode Mode Test: A forward voltage drop of 0.7V indicates a good diode junction. No voltage drop indicates an open circuit or damaged junction.
• HFE Test: A reading of 100-200 indicates a good transistor with sufficient gain. A low reading indicates a weak or damaged transistor.
• Ohms Mode Test: A high resistance between the gate and source/drain indicates a good FET. A low resistance indicates a shorted gate or damaged FET.

Troubleshooting Transistor Issues

• No Voltage Drop in Diode Mode: Replace the transistor.
• Low HFE Reading: Replace the transistor.
• High Resistance in Ohms Mode for FETs: Check the gate-source/drain connection. Replace the FET if necessary.
• Low Resistance in Ohms Mode for FETs: Replace the FET.

Additional Tips

• Use a quality DMM with a high resolution.
• Ensure the transistor is properly seated in the DMM’s test sockets.
• Test the transistor in both orientations for diode and hFE tests.
• Refer to the transistor’s datasheet for specific testing parameters.

Summary: Empowering You with Transistor Testing Proficiency

Mastering the art of checking transistors with a digital multimeter in Sinhala empowers you with the ability to diagnose and repair electronic devices with confidence. By following the steps outlined in this comprehensive guide, you can effectively test transistors, identify their type, and troubleshoot any issues they may encounter. Embrace the knowledge and skills acquired through this guide, and become an expert in the world of semiconductors.

Questions You May Have

1. Why is it important to check transistors?
Transistors are vital components in electronic devices, and checking them ensures their proper functioning and prevents device failures.

2. What does the hFE test measure?
The hFE test measures the current gain of a transistor, which is an important parameter for amplifier circuits.

3. Can I use an analog multimeter to check transistors?
Yes, but analog multimeters may not provide as accurate results as digital multimeters.

4. What are the typical resistance values for FETs in ohms mode?
High resistance (several megaohms) between gate and source/drain indicates a good FET. Low resistance indicates a shorted gate or damaged FET.

5. How can I identify a damaged transistor?
A damaged transistor may exhibit no voltage drop in diode mode, a low hFE reading, or high/low resistance values in ohms mode for FETs.