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DIY an Autorange Capacitance Meter!

Sometimes, it’s hard to find the suitable capacitance meter, especially those that in the autorange version. Instead of searching it all over the places, it’s better to develop one for your own use!

Today, you’ll learn how to DIY an autorange capacitance meter! Since it’s in the autorange version, this also means it doesn’t need to adjust the range settings anymore! Moreover, the measuring range for this autorange capacitance meter is quite large as well, where it ranges from 5 pF all the way to 2600 uF. Don’t worry about the range, as it’s all taken care of by the PIC16F873A inside the circuit.

This project is based on a very simple circuit analysis principle of charging and discharging of capacitors in an RC circuit. Thus, the further components are not needed for complicated the task!

Basically, the capacitance meter is beginning by fully discharging the capacitor. After that, it will charge and waits until the voltage across the capacitor reaches 0.632 Vcc. Then, the time will be captured and the capacitance is computed using ‘Tau = RC’ formula. The result will be displayed on the LCD screen and the process will simultaneously repeat every subsequent 0.255s!

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