What is Diode?

Ever wondered how your oscilloscope or multimeter protects itself from reverse voltage? Or how a simple LED in your circuit indicates power? The answer lies in a fundamental electronic component: the diode

Diodes are tiny but mighty components in almost every electronic device. They act like one-way valves for electricity, letting current flow in one direction while blocking it in the other. Diodes control the flow of electrical current. They allow current to pass in one direction, but block it in the other. This simple function has many uses in electronics.

You've probably encountered diodes in electronic circuits. They're fundamental components. But what exactly are they, and how do they relate to your oscilloscope and multimeter? This blog will discuss what is diode and how an oscilloscope multimeter helps you test them. After you read it, we hope you will have a good understanding of diode

What is a Diode?

 A diode is a two-terminal electronic component that acts like a one-way valve for electricity. It allows current to flow in one direction (forward bias) and blocks it in the opposite direction (reverse bias).  

Think of it as a one-way valve for electricity. It's made from semiconductor materials, like silicon. These materials are treated to create a "PN junction."This junction is what allows current to flow in only one direction.

When voltage is applied in the "forward" direction, current flows. When voltage is reversed, current is blocked. This blocking is not perfect, a very small amount of leakage current will flow.

Diodes are essential in electronics for tasks like converting AC to DC (rectification), protecting circuits from reverse voltage, and regulating voltage. For oscilloscope users, understanding diodes enables accurate waveform analysis of rectifier circuits and transient voltage events. Multimeter users rely on diode testing functions to diagnose faulty components. Therefore, a grasp of diode behavior is crucial for anyone using these tools to troubleshoot and analyze electronic circuits.

Testing Diodes with an Oscilloscope Multimeter

ZOYI ZT-703S oscilloscope multimeter combines a digital multimeter (DMM) with an oscilloscope, offering precision and practicality for seamless diode testing.

Diode test function on a multimeter is a handy tool for checking the functionality of diodes, as well as other semiconductor devices like transistors.

How the Diode Test Works

Voltage Source:  The diode test function on a multimeter essentially provides a small voltage across the diode's terminals. This voltage is typically enough to forward bias a silicon diode.

Forward Bias:  When the multimeter's positive lead (red) is connected to the diode's anode and the negative lead (black) to the cathode, the diode is forward biased.

In this state, a good diode will allow current to flow, and the multimeter will display the voltage drop across the diode. This reading is usually around 0.5 to 0.8 volts for silicon diodes.

Reverse Bias:  When the leads are reversed (positive to cathode, negative to anode), the diode is reverse biased.

In this state, a good diode will block current flow, and the multimeter will display "OL" (over limit) or a similar indication of high resistance.

Interpreting Results:

Normal Diode: Forward bias: Displays a voltage drop (0.5-0.8V for silicon). Reverse bias: Displays "OL" or high resistance.

Shorted Diode: Displays a very low voltage (close to 0V) in both directions.

Open Diode:  Displays "OL" or high resistance in both directions.

The diode test function provides a limited current, which is safe for testing diodes. It's important to disconnect the diode from the circuit before testing it to ensure accurate readings.

While silicon diodes are the most common, other types of diodes (like germanium or LEDs) may have different voltage drops.

How to test diodes by ZOYI ZY-703S multimeter mode

Diode Test Mode: Measure forward voltage drop (e.g., 0.7V for silicon diodes) to verify health.

1. Press Mode button to enter Multimeter working mode.
2. In the continuity mode, press F2 to enter the diode test mode.
3. Connect the red test lead to the positive lead of the diode under test and the black test lead to the negative lead. Then, read the forward voltage displayed on the screen. If the test lead polarity is reversed or the diode is faulty, the screen will display " ".

Continuity Check: Detect shorts or open circuits.

1. Insert the black test lead into the COM terminal, and the red test lead into the VΩHz terminal.
2. Switch to the continuity mode by pressing the F2 key when in the resistance range.
3. Connect the test leads to the two points of the circuit under test; if the built-in buzzer sounds, it indicates a short circuit.

The diode test on a multimeter allows you to quickly assess whether a diode is functioning correctly by checking its forward and reverse bias characteristics.

How to test diodes by ZOYI ZY-703S Oscilloscope mode

Using multimeter mode gives you the vv simple  "pass/fail" . That's fine for basic checks. But what if you want to see how it behave while test a diode? That's where an oscilloscope shines. An oscilloscope provides a dynamic, visual representation of a diode's behavior.

Here's how an oscilloscope helps visualize diode behavior:

I-V Characteristic Curve:

An oscilloscope can display the diode's current-voltage (I-V) characteristic curve. This curve reveals how the diode's current changes as the voltage across it varies.

This visualization shows the distinct forward and reverse bias regions. You can see the "knee" of the curve where the diode begins to conduct significantly in the forward direction.

It also allows observation of the reverse breakdown region, where excessive reverse voltage causes a dramatic increase in current.

Rectification:

By applying an AC signal to a diode circuit, an oscilloscope can vividly display the diode's rectification properties.  

You can observe how the diode clips or eliminates either the positive or negative half of the AC waveform, demonstrating its ability to convert AC to DC.

This is particularly useful for visualizing half-wave and full-wave rectification circuits.  

Waveform Analysis:

Oscilloscopes can capture and display transient diode behavior, such as switching speeds and voltage spikes.  

This is crucial for analyzing diodes in high-frequency circuits or switching applications.

It enables the observation of diode recovery time, which is the time it takes for a diode to switch from a conducting to a non-conducting state.

Signal Clipping:

Oscilloscopes can show how diodes are used to clip signals at certain voltage levels. This is useful in signal processing and protection circuits.

The oscilloscope will display the input signal and the output signal, visually showing how the diode is limiting the voltage.

In a word, an oscilloscope provides a time-domain view of diode behavior, showing how voltage and current change over time.  

It allows for detailed analysis of diode characteristics, including forward voltage drop, reverse breakdown voltage, and switching speeds.  

It is invaluable for designing and troubleshooting diode circuits, especially in applications involving AC signals and high frequencies.  

Therefore, while a multimeter can tell you if a diode is generally working, an oscilloscope shows you how it's working, and that's a much more in depth view.

Here a brief steps by using Oscilloscope mode,

1. Connect probes to a live circuit with the diode.

2. Press Mode button to enter working oscilloscope mode.

1. Look at the waveform:

1. Healthy diode: Clean half-wave or full-wave rectification.
2. Faulty diode: Distorted waveforms, unexpected spikes, or no signal.

Diodes in Practical Circuits (Applications)

Diodes are fundamental components in a vast array of practical circuits. Here are some common applications,

• Rectifying AC power.
• Protecting circuits from reverse voltage.
• Indicating power with LEDs.
• Regulating voltage with Zener diodes.

Safety Considerations

Measuring diodes is generally safe, but it's important to follow some safety precautions to protect yourself and your equipment.

Diodes are sensitive. You must handle them carefully. Damage is easy.

• ESD is a risk. You might need an anti-static wrist strap. Semiconductor junctions are vulnerable.
• Physical stress is a problem. Do not bend leads excessively. Small diodes break easily.
• Heat damages diodes. Avoid prolonged soldering. Use proper techniques.
• Power down circuits. You must disconnect power before handling. This prevents electrical damage.
• Check polarity. Incorrect connections can destroy diodes. Pay attention to anode and cathode.
• Use the correct tools. Avoid using excessive force. Proper tools prevent physical harm.
• Store diodes safely. Use anti-static bags. Prevent physical damage.
• You must discharge capacitors. Capacitors can hold charge. This charge can damage diodes.

Proper handling ensures diodes function correctly. You avoid premature failure. This saves time and money.

Exceeding a diode's maximum ratings puts the component at risk. These limits exist for a reason.

• Voltage breakdown: You might cause irreversible damage. Too much reverse voltage destroys the diode's junction.
• Thermal runaway: Excessive current leads to overheating. This can melt the diode or cause it to fail.
• Instantaneous failure: High current spikes can instantly destroy the diode.
• Reduced lifespan: Even small overloads can shorten the diode's operational life.
• Circuit damage: A failed diode can damage other components in the circuit.

Always consult the diode's datasheet. Respect its voltage and current ratings. This prevents costly failures and ensures circuit reliability.

Why Choose ZOYI ZT-703S Oscilloscope Multimeter?

 ZOYI ZT-703S Oscilloscope is a marvel of technology, blending innovation and versatility, witch seamlessly between DMM and oscilloscope.

• Dual Functionality: Save time switching between tools.
• Precision: High-resolution displays for accurate waveform analysis.
• Durability: Built to handle rugged testing environments.
• User-Friendly: Auto-sensing ports and intuitive interfaces.

Conclusion

Reinforce that understanding diodes is critical for electronics work, and having the right tool (like your oscilloscope multimeter) makes troubleshooting faster and more precise. 

Diodes are fundamental electronic components. They are used in numerous circuits. Understanding how they work is helpful when using your oscilloscope and multimeter. You can use these tools to test diodes and analyze their behavior.

Accurate current measurement allows us to diagnose issues, ensure safety, and optimize performance. By understanding how to connect a multimeter in series and interpret readings, you gain valuable insights into circuit behavior.

We encourage you to explore the diverse range of multimeters we offer. ZOYI Online Shop is providing Digital Oscilloscope, Smart Digital Multimeter, Professional Digital Multimeter, Auto-range and manual range Multimeter,Double Injection Digital Multimeter, Bluetooth Digital Multimeter etc. With various features and capabilities, you can find the perfect tool to measure current accurately and safely, empowering you to tackle any electrical task with confidence.Superior customer support, free shipping service and 12 month warranty are ensure you get a reliable current measurement tool.

Have questions about how to measure capacitance in your projects? Contact our team for expert advice on choosing the right tool for your needs!