How do I know the polarity of the output wires from a source or a battery eliminator? With this simple circuit we have the direct indication for voltages from 3 to 12 V, without problems.
If PP1 is positive in relation to PP2, LED1 lights up. If PP1 is negative and PP2 is positive, then LED2 lights up. The circuitry consumes little current and can be used in circuits and sources.
In Figure 1, we have the diagram and the assembly of the polarity indicator on a small terminal bridge. To make it easier to identify we suggest using different colored LEDs.
Figure 1 - Diagram and assembly of polarity indicator | Clique na imagem para ampliar |
Material list
LED1, LED2 - Common LEDs of different colors
R1- 1.5 k ohms x 1/8 W- resistor - brown, gray, red
PP1, PP2 - probes, terminal strip, wires, solder, etc.
