Short Circuit Indicator

In this Instructable you will be making a short circuit indicator.

You will need:

- electrical box,

- two AA or AAA battery holder (power supply),

- A few LEDs (you only need one but you might burn a few),

- wire stripper,

- 0.9 mm or 1 mm metal wire,

- drill,

- scissors,

- pencil,

- 100 ohm resistor,

- wires,

- solder and soldering iron,

- screw driver,

- vise (optional),

- matrix board (optional),

- multi-meter (optional),

- power supply (optional).

Step 1: Test the LED

Set the power supply to 2 V. Do not increase or you will burn the LED.

Note the longest pin is the positive terminal as shown in the photo.

Step 2: Connect the LED

Use solder and soldering iron to connect the LED to wires.

Step 3: Drill a Hole for the LED

Make the hole on the box with a pencil. Note the blue line showing where the hole should be. The LED should be placed on top of the plastic fixture.

Use the drill to drill a very narrow hole. Use scissors to widen the hole for the LED. Warning! Do it slowly or you will cut yourself.

Step 4: Build the Circuit

PSpice software was used for simulations. The LED is modelled with three general purpose diodes (each diode has a voltage of 0.7 V across it).

In this circuit I used two 180 ohm resistors. You can use two 220 ohm resistors or one 180 ohm resistor with one 220 ohm resistor.

To calculate the resistor value I used the follow basic formula: (Vbattery - Vled) / Iled = (3 V - 2 V) / 10 mA = 100 ohms.

Use screw driver to connect the circuit.

Step 5: Put the Box Lid On

Use screw driver to secure the box lid to electrical box.

You are now done.

You can see the circuit operating in this video: