DIY Arduino LC Meter: Easy Inductance and Capacitance Measurement

Measuring accurate inductance and capacitance values is essential for circuit design and troubleshooting in electronics projects. However, commercial LC meters can be expensive and might not always meet your specific needs. In this project, we’ll create an Arduino-based DIY LC Meter, offering a cost-effective and customizable solution.

This LC meter, built with an Arduino Nano, provides:

1. A wide range of inductance and capacitance measurement
2. High accuracy
3. Simple setup and operation

The project is suitable for both beginners and experienced electronics enthusiasts. Additionally, as an open-source design, it’s easy to modify and tailor to your preferences. In this step-by-step guide, we’ll cover everything from circuit assembly to code uploading and device testing.

Are you ready? Let’s build our own LC meter and take our electronics projects to the next level!

To build this DIY LC Meter, you'll need the following components:

1. Microcontroller
2. 1x Arduino Nano
3. Display
4. 1x 16x2 LCD with I2C Serial Backpack
5. Passive Components
6. Resistors:
7. 3x 100 kΩ
8. 1x 4.7 kΩ
9. 1x 47 kΩ
10. 1x 6.8 kΩ
11. 1x 1 kΩ
12. Capacitors:
13. 2x 10 µF
14. 2x 1 nF
15. Inductor
16. 1x 100 µH
17. Diodes and Transistors
18. 1x 1N4007 diode
19. 1x BC547 transistor
20. IC and Relays
21. 1x LM311 comparator IC
22. 1x 5V relay (5V/10mA)
23. Switches
24. 4x Push button switches (for calibration and adjustments)
25. Connectors and Jumpers
26. 1x 2-pin connector for inductance/capacitance selection (Cx/Lx)
27. Jumpers JP1 and JP2
28. Power Supply
29. 1x 5V power source
30. Miscellaneous
31. Breadboard or PCB for circuit assembly
32. Connecting wires

The schematic forms the foundation of our DIY LC Meter project. Let’s break it down into key sections for better understanding:

1. Measurement Selection (Cx/Lx):
2. The switch (SW1) allows you to toggle between capacitance (Cx) and inductance (Lx) measurement modes. The 2-pin connector (J1) is used to connect the component under test.
3. Oscillator Circuit:
4. The LM311 comparator IC is used to create an oscillator circuit. The oscillation frequency changes based on the inductance or capacitance connected to the circuit. This frequency is later measured and processed by the Arduino.
5. Relay Control:
6. A BC547 transistor drives the 5V relay (RL1), which helps in switching between different parts of the circuit. The relay operation is controlled via the Arduino.
7. Passive Components:
8. Resistors and capacitors in the circuit are used for biasing, frequency adjustment, and filtering. For instance, R2 (6.8 kΩ) and R3 (4.7 kΩ) set the reference voltage for the LM311.
9. Microcontroller (Arduino Nano):
10. The Arduino Nano reads the frequency from the oscillator circuit and calculates the inductance or capacitance value based on a predefined formula.
11. The microcontroller also handles user input via switches (S1, S2, S3, S4) and displays the measured value on the 16x2 LCD.
12. Display Section:
13. A 16x2 LCD module with an I2C backpack is used for easy connection and minimal pin usage. It displays the measurement mode (Cx or Lx) and the calculated value in real time.
14. Calibration and Adjustment:
15. Push buttons (S2, S3, S4, S5) allow you to calibrate the device, set it to zero, or adjust other parameters.
16. Power Supply:
17. The circuit operates on a 5V power supply, which powers the Arduino, LCD, and other components.

This schematic combines simplicity with functionality, making it a great project for hobbyists and electronics enthusiasts. In the next step, we’ll move on to assembling the components on a breadboard or PCB. Stay tuned!

Now that we understand the schematic, it’s time to gather all the components and assemble the circuit on a breadboard for testing. Follow these steps to get started:

1. Gather the Components:

Make sure you have the following items:

1. Arduino Nano
2. 16x2 LCD with I2C Backpack
3. LM311 Comparator IC
4. 1N4007 Diode
5. BC547 Transistor
6. 5V Relay (5V/10mA)
7. Inductor (100 µH)
8. Capacitors:
9. 2x 10 µF
10. 2x 1 nF
11. Resistors:
12. 3x 100 kΩ
13. 1x 47 kΩ
14. 1x 4.7 kΩ
15. 1x 6.8 kΩ
16. 1x 1 kΩ
17. Push Buttons (x4)
18. 2-Pin Connector for Cx/Lx Testing
19. Jumpers (JP1, JP2)
20. Breadboard
21. Connecting Wires

2. Assemble the Circuit on the Breadboard:

1. Power Connections:
2. Connect the 5V and GND rails on the breadboard to the Arduino Nano. These will power all components.
3. Oscillator Circuit:
4. Place the LM311 comparator IC on the breadboard.
5. Connect the resistors (R2, R3, R4) and capacitors (C3, C4) around the LM311 according to the schematic.
6. Insert the 100 µH inductor (L1) to complete the oscillator circuit.
7. Relay and Transistor Section:
8. Place the BC547 transistor and the 5V relay on the breadboard.
9. Connect the diode (D1) across the relay coil for protection.
10. Wire the transistor base resistor (R7) and connect it to the Arduino control pin.
11. Switches and Jumpers:
12. Insert the push buttons (S2, S3, S4, S5) for calibration, zeroing, and adjustments.
13. Add the jumpers (JP1, JP2) to the breadboard to toggle between measurement modes.
14. LCD Display:
15. Connect the 16x2 LCD with I2C backpack to the Arduino Nano using the SDA and SCL pins.
16. Measurement Input:
17. Use a 2-pin connector for the component under test (Cx/Lx).

3. Verify Connections:

1. Double-check all connections with the schematic to ensure accuracy.
2. Pay special attention to power supply polarity and the connections for the LM311, relay, and Arduino pins.

4. Prepare for Testing:

With all components in place, your breadboard setup is ready for testing. In the next step, we’ll upload the Arduino code, calibrate the device, and test the circuit.

Stay tuned and make sure your connections are secure!

In this video, I'll show you how to build a DIY LC Meter using an Arduino Nano. This device measures inductance and capacitance with precision, making it an essential tool for electronics enthusiasts.

We'll cover:

1. The schematic and components
2. Breadboard assembly
3. Calibration and testing

By the end, you’ll have a fully functional LC Meter that’s cost-effective and easy to build. Let’s get started!

The Arduino code for this DIY LC Meter is available on GitHub. You can also find the KiCad project files for the schematic and PCB design. Simply download everything from the following link:

👉 GitHub Repository - TeknoTrek/LC-Meter

Upload the code to your Arduino Nano, and you're ready to calibrate and test your LC Meter!

Power up your DIY LC Meter using a 5V power supply, and you're ready to measure inductance and capacitance with precision! Use the calibration buttons to set it up, connect your component under test, and watch the values display on the LCD.

Congratulations on completing this project! I hope you had fun building your own LC Meter and gained valuable insights into its working principles. Feel free to share your version of this project or reach out with any questions or feedback.

If you enjoyed this project, be sure to subscribe to my YouTube channel, Teknotrek, for more exciting electronics tutorials and DIY projects. Thanks for following along, and I look forward to seeing you in the next project! 🚀