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).

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.

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

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.

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.

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

You are now done.

You can see the circuit operating in this video: