Capacitance Meter

Timeline

September 2024 – November 2024

Implementation Details

Tools: Teensy Microcontroller, Altium, and LTspice.

Teammate: Donald P.

Specifications

• Wall powered, 5V DC only.
• Auto ranges between 20 pF and 200 µF.
• Resolution: the display has 7 total digits going from 0.0000 to 999.9999 in pF to µF, measurement is accurate within 3 and ½ digits.
• Accuracy: 3% from 2 nF to 2 µF, and 10% from 20 pF to 2 nF and 2 µF to 200 µF.
• Update with a button press.
• Does not require any laptop or other computer to operate, just requires a power source.
• Utilizes clip lead to clip lead adapters to connect to capacitors and 2 test points located on the board labeled Clipper+ and GND for positive end and ground end respectively.

Source Code:

Link to the GitHub repository: Capacitance Meter Code

Planning

Tasks Checklist:

• Project timeline planning
• Preliminary method research
• Initial schematic design
• Design review 1
• Schematic design with feedback integration
• PCB design
• Design review 2
• Feedback integration
• Testing components
• Breadboard prototype
• PCB ordering
• Software design
• PCB assembly
• Measurement testing
• Measurement calibration
• design
• Documentation and report

Design

Theory of Operation:

To measurement capacitance, we use the constant current source method, deriving from the capacitor equation.

In this equation, we hold the current constant and charge the capacitor to a certain threshold, which is 1 V in our design, the calculated capacitance after rearranging the equation above is as follows:

Software Flowchart:

Software Flowchart

PCB:

The PCB has 2 layers:

• Signal (top layer)
• Ground

Below is a picture of each layer:

Top Layer

Bottom Layer

Top and Bottom Layer

Outcomes:

Below are the pictures of the finished prototype breadboard, PCB, and case.

Breadboard Prototype

Capacitance Meter PCB

Capacitance Meter PCB with Case

Capacitance Meter PCB in the Case