Testing circuits can be done with multi-meters and oscilloscopes but this is not always the best method. For example not everyone has access to an oscilloscope and multi-meters are no good for fast changing signals. Another reason is ease of use, testing a circuit with an oscilloscope can be tricky as you need to probe the contact and then turn away to look at the display. All it takes is for the probe to slip slightly and then the oscilloscope will be showing the signal trace for a completely different connection.
This is where the faithful logic probe saves the day! Instead of having numbers to show voltages or a display to show signals over time the logic probe has just three LEDs for outputs. These outputs can show on, off, floating, and oscillating! So long as the probe has a common ground to the circuit under test (which can be done easily by either using the same power supply or connecting the probes GND-REF to the circuits ground), the probe will display one of the four listed conditions above when the probe contact is connected to a point in the circuit. But how does this probe work? Get this kit and find out!