Introduction: 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,
- 100 ohm resistor,
- 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:
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