Liquid Conductivity Tester
Électronique / Electronic

Back in Project Rain Detector in Oscillator section, we found out how to test how well salt and fresh water could conduct electricity.

This Project is a deluxe conductivity tester for liquids. To use this Project, simply place the exposed metal ends of the two long wires in a liquid. Put the power ON and adjust it until the Meter pointer is about halfway up the scale. Note carefully where the pointer is.

Remove the two Long wires from the liquid and wipe the exposed ends dry. Make sure you have all of the liquid removed. Now dip the ends of the long wires into a second liquid. Make sure you have the two ends spaced the same distance apart as in the first liquid, Read the Meter pointer now. The higher the reading, the better the liquid can conduct electricity.

Try this on some common liquids found in your home-but avoid chemicals, cleaning fluids or liquids which might catch fire. Try such common things as vinegar, soft drinks, soapy water, cooking oil, etc.

Notice how the two transistors are connected in the schematic. This is called a 2-stage direct coupled circuit. Keep a record of the liquids you test. Which ones conduct electricity best? You can also use this Project to test solids for conductivity.