The advancement in light-emitting diode (LED) technology has allowed the LED to become a fundamental component in electronics. LED flashers have many applications. With a few electronic components, anyone can build an LED flasher and control variables such as frequency and the amount of time that the LED remains on during one time cycle. There are many ways to create LED flasher circuits. One of the easiest designs uses a common 555-timer chip. This design has a frequency of about 4 Hz.
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Things you need
- 555-timer chip(NE555N or equivalent)
- 2 resistors (1 mega-ohm)
- 1 resistor (333-ohm)
- 2 capacitors (1 microfarad)
- 9-volt battery
- Electrical wire
- Electronics breadboard
- Wire cutters
- Voltmeter (optional)
Place the 555 chip, resistors, and capacitors on the breadboard as seen in the LED Flasher Circuit Schematic found in the Resource section. Resistors R1 and R2 in the schematic have a resistance of 1 mega-ohm.
Connect a wire to a common ground rail on your breadboard using the negative terminal of your 9-volt battery. Connect a wire to a rail and designate it as the Vcc rail on your breadboard using the positive terminal of your 9-volt battery as shown below. Connect wires from your 9-volt battery to the designated ground and Vcc rails.
Connect the LED between the 330-ohm resistor and the ground rail.
Connect pin 4 and 8 to the Vcc rail. Connect pin 6 to pin 2. Connect both capacitors to the ground rail. You should now see the LED blink on and off around two times a second.
Alter the frequency of the circuit's output signal by exchanging resistors. Changing the 1-mega-ohm resistors to higher will cause the LED to flash slower. Decreasing the value of the resistors will cause the LED to flash faster.
Transfer the LED flasher circuit from your breadboard to a permanent circuit board and solder into place. Place the soldered circuit into an enclosure that is durable enough to stand the hazards of your circuit's application.
Tips and warnings
- The LED and capacitors must be placed into the circuit a certain way. Make sure you know which side of your capacitor is positive and which is negative. The negative side of a capacitor generally has a (-) symbol pointing to the equivalent terminal. The LED must be placed in the circuit with the cathode connected to the ground rail. The cathode is the pin coming off of the diode that is usually the shortest. If you can not tell which side is the cathode by looking at the wires coming off of the diode, look at the LED from the side and the side that is the longest internally is the cathode.
- Always use caution when dealing with electricity and electronics due to risk of electrical shock.
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