There are many articles about measuring capacitance using an Arduino. In the simplest form they just measure the time to charge or discharge the capacitor with known voltage through a resistor. But some are elegant, requiring no additional components at all!. This concept seems a little ridiculous, but see the articles on Codewrite.co.uk by Jonathan Nethercott, linked to in the references section below. With a bit of inspired thinking and ideas from others an elegant solution to capacitance measurement was born. This approach needs some calibration as it depends upon values of internal stray capacitance and pull-up resistors in the Arduino, and may not even work for some types of Arduino (and clones).

To test out the viability of this approach I constructed a basic implementation using an Arduino Duemilanove.

Here is my initial program using Jonathan's code and a driver for a serial LCD :
Capacitor meter code for Arduino UNO and KS0073 display.

So that's proof of concept. A pretty simple project, but very useful as I've never had a meter to measure capacitance. Many of the LCD display modules have external capacitors, mainly for the negative charge pump circuits for the LCD drive, now I'll have a way to find out what value they are.

Next will be to mount this in an enclosure, perhaps an old multi-meter body, to make it a bit more rugged than a testbench circuit.

• Capacitance Meter Mk II by Jonathan Nethercott
• Capacitance measurement with the Arduino Uno by Jonathan Nethercott
• Capacitance measurement with the Arduino Uno by Jonathan Nethercott
• Arduino capacitor by Jonathan Nethercott

• Cap meter Arduino by Gavin Lyons
• Autorange Capacitance Meter
• Arduino multimeter
• Capacitance Measurement using Arduino
• Measure Capacitance With Arduino
• Capacitance Meter Example

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