How to Power an LED Circuit
Light emitting diodes, or LEDs, are used in electrical and electronic circuits as indicator lights, flashlight bulbs, and other applications where light is needed. Because an LED has lower power requirements and generates less heat than incandescent bulbs, LEDs can be used in many places that incandescent bulbs cannot be used.
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Things You'll Need
- Light emitting diode (such as Rohm Semiconductor SLR-343)
- Two AA batteries
- Battery holder
- 150Ω electrical resistor
- Electrical wire
- Electrical pliers
- Soldering iron and solder
Instructions
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1
Cut a length of wire, and strip each end of 1/2-inch of insulation. Solder one end of the wire to the positive terminal on the battery holder. Solder the other end of the wire to the anode lead on the LED.
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2
Solder one of the resistor leads to the cathode lead on the LED. Cut a second length of wire, and strip each end of 1/2-inch of insulation. Solder one end of the wire to the unsoldered resistor lead. Solder the other end of the wire to the negative terminal on the battery holder.
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3
Insert batteries into the battery holder to power the circuit. Remove the batteries to turn the circuit off.
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Tips & Warnings
Other DC power sources, such as a 3V AC-to-DC adaptor, may be used in place of the battery and battery holder combination. To use a power adaptor, substitute the positive wire and negative wire on the power adaptor for the positive and negative terminals on the battery holder. Plug the power adaptor into a wall outlet to power the circuit.
Light emitting diodes are polarized electronic components. The anode is the "positive" lead; the cathode is the "negative" lead. If the polarity is switched (positive connected to cathode, negative connected to anode), the LED will not light up. The cathode lead on a round-lens LED is usually the shorter of the two leads. The cathode may be further identified as having a flat spot near the cathode on one side when looking at the LED lens.
