How to Make an LED Light Blink
An LED, also known as a light emitting diode, can be made to blink. Not only can the LED be made to blink manually, but it can also be made to blink by itself. Regardless of the method you choose to make your LED blink, you will need other electronic components to make the LED blink. For simple designs, all you will need is a manual switch.
Things You'll Need
- 5 volt flashlight battery
- Toggle switch
- Circuit wire connectors
- 100 ohm resistor
Connect a toggle switch in parallel with your LED. Connect the anode of the LED to the switch's left connection terminal then connect the cathode of the LED to the switch's right connection terminal. Remember a toggle switch is controlled by a push button. When the button is pushed, a metal wire is either removed or placed across the two terminal connections of the switch.
Calculate the limiting resistor value for the LED. Assume that the LED you are using requires 2 Volts across it to light it, and that the electrical current to light the LED brightly is 30 milliamperes (remember one thousand milliamperes is equal to one ampere). Also consider that you will use a 5 Volt battery to power your LED blinking circuit. Now subtract the battery voltage from the required LED voltage to obtain 3. Now divide this result, 3, by the LED current required. Since 3 divided by 0.03 is 100, the resistor value you will need is 100 ohms.
Connect the parallel switch / LED arrangement constructed in the first step in series with your battery and the current limiting resistor. First connect the positive terminal of your battery to one end of the 100 ohm resistor. Next connect the other end of the 100 ohm resistor to the parallel switch / LED arrangement. Connect the resistor such it connects to the anode of the LED lead. Now connect the other lead of the parallel switch / LED arrangement to the negative terminal of the power supply.
Test your circuit. Turn on your battery and press the toggle switch. Repeatedly press the toggle switch and notice that each time you press the toggle switch the LED will blink on or off.
Tips & Warnings
- This circuit design consumes power when the LED is on and off. Modifications could be made to such that the circuit would only require current when the LED is on.
- For self-blinking designs, you will need an oscillator, that is a device that automatically generates an electronic waveform. If you want to make the LED light blink by itself, obtain or design an oscillator. Use the oscillators output waveform to turn the LED on and off at set intervals. Consider that, just as you did with the toggle switch design, you will need to place a current limiting resistor between the output of the oscillator and the LED,
References & Resources
- Tony R. Kuphaldt: Lessons In Electric Circuits -- Volume IV
- Redcircuits: 1.5V LED Flasher Oscillator - RED - Page87
- QSL: LED Circuits Page
- Simple LED flasher circuits
- QRP: Fun with LEDs
- MadLab: Two Flashing LED Astable Oscillator Electronic Kit AMK102B
- Electronic Design: Dual-Gate Inverter Oscillator Saves Power, Boosts LED Brightness
- Circuit - 1.5V LED FLASHER VERSION A - Circuits designed by David A. Johnson, P.E