In Figure 1 we present a simple continuity test that can be used not only in component and circuit testing, but also for elementary computer type assemblies and conductivity tests in classes.
The circuit operates with a very low test current, which means that it can test most of the most delicate electronic components without the danger of them being overloaded.
The assembly can be carried out on the basis of a bridge of terminals, as shown in figure 2.
The LED is of any color, and its polarity, given by the flat side of the enclosure must be observed because if it is inverted, the circuit does not work.
To test, touch one probe on the other. The LED should light up. To use the test leads on the terminals of the component to be tested. If the LED lights up, there is continuity.
Never use the tester on any circuit that is turned on as this may cause the circuit components or the tester's own LED to burn.
The circuit will also operate with two small batteries, that is, 3V of supply voltage.
Material list
LED1 - LED red or any color
PP1, PP2 - Red and black probes
R1 - 330 ohms x 1/8 W - resistor - orange, orange, orange
B1 - 6 V - 4 small batteries
Miscellaneous:
Battery holder, terminal bridge, wires, solder, etc.
