In this instructable I will show you how to make a simple polarity tester capable of out to about 12vdc.
Step 1: Materials
-4 diode (must at least withstand 12vdc)
-1 red LED
-1 green LED
-1 1k ohm resistor
Step 2: How to Know How to Position Diode on Circuit Board
You should notice a white, Grey or other color banned on your diode, this is were it goes on a schematic.
Step 3: The Circuit
-D4 to 7=Diode
-R1=1 k ohm resistor
Step 4: Now Your Done!
Now that your done you can use it for any circuit testing under 12vdc.