ARDUINO CAPACITANCE METER

06.10.2016

Idea:

I was looking for a simple way to measure lower capacitance values; from 1 pF to 1µF. Why ? Because I have a lot of recicled capacitors; and on some of them the reading is impossible or requires a magnifying glass ;) I do have a multimeter, but its pretty cheap and simple, and has not this feature. So I started to investigate...

I found a lot of Arduino projects to measure capacitance, but this one is really simple and very elegant, and no additional parts than an Arduino are required ! :)

http://wordpress.codewrite.co.uk/pic/2014/01/21/cap-meter-with-arduino-uno/

Thanks to Jon for this great job !

Current Status:

I decided to use an Arduino Leonardo, because it is not that big than Arduino UNO or Mega. No additional change in code was needed. I just calibrated the internal pull-up resistor of my Arduino as Jon described in the post, and come to a value of 34,7 kOhm. To perform calibration, I recommend to use several capacitors; I used 100 nF. I also would recommend 1µF, but not electrolyt, as Jon described. Why ? Well, standard electrolyt capacitors has a lot of tolerance, sometimes >20%.

Program works fine, and tolerace is pretty good. Value is visible on terminal window. No need to push any button; program just keeps on sensing all the time.

Tip: to measure electrolyt condensator, use PIN A2 for plus (+) and PIN A0 for minus (-).

Next steps:

Port this project to Arduino Nano, and use a 1602 display to show the value. Put everything in a small case with a 9V block battery, and that´s it.

System running:

Calibrating internal pull-up resistance of my system:

Testing three different 100 nF capacitors (Terminal output):

Capacitance Value = 0.096 pF (4)

Capacitance Value = 102.10 nF (Normal, t= 1304 us, ADC= 315)

Capacitance Value = 102.42 nF (Normal, t= 1308 us, ADC= 315)

Capacitance Value = 102.10 nF (Normal, t= 1304 us, ADC= 315)

Capacitance Value = 102.42 nF (Normal, t= 1308 us, ADC= 315)

Capacitance Value = 102.10 nF (Normal, t= 1304 us, ADC= 315)

Capacitance Value = 102.02 nF (Normal, t= 1308 us, ADC= 316)

Capacitance Value = 102.42 nF (Normal, t= 1308 us, ADC= 315)

Capacitance Value = 71.104 pF (761)

Capacitance Value = 0.120 pF (5)

Capacitance Value = 0.096 pF (4)

Capacitance Value = 100.85 nF (Normal, t= 1288 us, ADC= 315)

Capacitance Value = 101.16 nF (Normal, t= 1292 us, ADC= 315)

Capacitance Value = 100.46 nF (Normal, t= 1288 us, ADC= 316)

Capacitance Value = 100.85 nF (Normal, t= 1288 us, ADC= 315)

Capacitance Value = 101.16 nF (Normal, t= 1292 us, ADC= 315)

Capacitance Value = 100.85 nF (Normal, t= 1288 us, ADC= 315)

Capacitance Value = 71.104 pF (761)

Capacitance Value = 0.120 pF (5)

Capacitance Value = 0.096 pF (4)

Capacitance Value = 101.71 nF (Normal, t= 1304 us, ADC= 316)

Capacitance Value = 98.59 nF (Normal, t= 1264 us, ADC= 316)

Capacitance Value = 98.28 nF (Normal, t= 1260 us, ADC= 316)

Capacitance Value = 71.104 pF (761)

Capacitance Value = 0.120 pF (5)

Capacitance Value = 0.096 pF (4)