Blinking LED Circuit with Schematics and Explanation
The blinking LED circuit is like the electronics version of the “Hello World”-program. It’s a simple electronic circuit that gives you a visual cue if it works. It was the first circuit I ever built, and it felt GREAT!
The goal is to make a Light Emitting Diode (LED) blink.
Three Different Ways To Build A Blinking LED Circuit
There are several ways of making a blinking LED circuit. You can make one using relays. You can make one using transistors. Or you can make one using components like an inverter, a 555 Timer or a microcontroller.
I’m going to show you three ways to build a blinking LED circuit using:
- A relay
- A transistors
- An inverter
Blinking an LED Using Relays
The easiest way to get a light to blink (or at least the easiest to understand) is the following:
In the above circuit you see a battery, a relay (in the red square) and a light bulb. To understand the circuit you need to understand how a relay works.
When the relay coil has power, the switch will disconnect the power from the electromagnet and connect the power to the light bulb instead so that it will light up.
But when the relay no longer has power, it will switch back and turn off the power from the light bulb and give power back to the electromagnet again.
Then the cycle starts over.
The problem with the circuit above is that it will switch so fast that you won’t actually see the light blink.
When you apply power to the above circuit, the battery starts charging the capacitor through resistor R2.
After a moment, the relay coil pulls the relay into the other position.
This makes the LED turn OFF.
Because the capacitor now is charged, it will hold the relay in this position. But the capacitor only has enough energy to keep the electromagnet in the relay powered for a little bit before it’s empty (or discharged).
When the capacitor is out of energy, the relay goes back into its original state and turns the LED ON again.
Then the cycle repeats itself.
For this circuit with the above component values I recommend the DS2Y-S-DC5V relay or a similar one.
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