Logic Probe

                                                               Logic Probe

The Tester is only for 24volts or less .

Connect the red clip to the positive side of the battery and the black clip onto the negative (earth).Both of the red and green LEDs should turn on , this shows the connections and that the tester in properly hooked up.When you touch the brass probe end to the positive on the battery the green LED should go out and the red Led will go brighter , when you do the same on the negative the red Led should go out and the Green LED should go brighter .

List of Parts :
Brass Rod 150mm Long
Red LED
Green LED
Black wire
Red Wire
2 Resistors 1k Ω
Red Alligator clip
Black Alligator clip
100mm Plastic Tube
And some Shrink tubing

Very simple and easy to make ,first we solded a resistor to each led then solded them to a long peice of wire , later we put heat shrink over the the resistor and spreaded the legs of the LED apart.

Then we get the brass rod and tined the middle with some solder , later we placed heat shrink on the side to insulate the brass rod.

We then solded the LED's to the tinned area of the brass rod , also we put some glue to give the LED's more support and took the wires to one side of the Brass rod , then placed heat shrink over it .

Finally onto the last steps , we get a plastic support tube and cut the one end as long as both leds and abit more then placed in were the wires come from like in the picture below.