Simple Continuity Tester
A simple $5 continuity tester is shown in Figure 2-3. It consists of a metal

probe and indicator light powered by two AAA batteries. The probe is one lead of the continuity tester and can be touched to the end of a wire or inserted into a connector hole. The second lead is a clip lead that comes out of the body of the
tester.
To use the continuity tester, insert the batteries and then touch the probe to the clip on the lead. The light should go on. (Always perform this preliminary step before using any continuity tester. It verifies that the continuity tester is working!) Now, connect the test lead to one end of the wire to be tested and the probe to the other end of the wire to be tested. If the wire is not broken, the light should come on.

Latching Continuity Tester

A latching continuity tester is shown in Figure . This tester is powered by a
9-volt battery inside the case and has an LED (light emitting diode) lightas well as a
buzzer. It has several different ways it operates.
Testing for ContinuityTo test for continuity, set the switches to NORMALLY OPEN and MOMEN-T ARY and then turn POWER ON. Now connect one test lead to one end of a wire to be tested and the other test lead to the other end of the wire to be tested. The buzzer will sound and the LED light will go on if the wire has continuity.

Testing for Normally Open Circuits
Some circuits, in home security systems, are normally open. This means that switches are closed when a door or window opens or vibration (such as breaking glass) occurs. A typical circuit is shown in Figure 2-5. To test a circuit such as this, set the switches to NORMALLY OPEN and MOMENTARY and then turn POWER ON. Now connect one test lead to one end of a wire to be tested and the other test lead to the other end of the wire to be tested. The buzzer will not sound if the circuit is open. Closing any switch will cause the buzzer to sound.