LED (Light Emitting Diode) is a two-lead semiconductor light source and this small device is integrated into most of the electronic circuits for different indication purposes because of the glowing property e.g. power indication, status indication and. and similarly, the blinking of LED (on and off duration of the LED ) has added many different applications like aviation lighting, IoT devices status indication, camera capture indication and also reduces the overall consumption of devices because the device is powered off at a certain time.
To turn on the two-terminal device(LED) connect the anode with the positive terminal of the battery and connect the resistor in series with the led to restrict the current flow and connect the other end of the resistor with the negative terminal of the battery. The light emits because the electron moves from p-type to n-type and emits the photon of light.
We are able to blink the led using two popular methods using the PWM wave generate through charging and discharging of the capacitor or generating the PWM wave from the Specific Pin of the microcontroller. Therefore, Blinking Led reduced the no of LEDS explaining different statuses just varying the blinking pattern instead of using multiple LEDs
Voltage Drop Across LED:
The Voltage drop across the LED is normally 1.7 – 2.0 V but in this created led blinking using 1.5V and it is done just by adding NPN, PNP Transistor, capacitor, and resistor.
Hardware Required
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1 | NPN Transistor | BC547 | 1 |
| 2 | PNP Transistor | BC557 | 1 |
| 3 | Led | – | 1 |
| 4 | Resistor | 100K, 1K, 470 ohm | 1, 1, 1 |
| 5 | Capacitors | 100nF, 10uF, 100uF | 1, 1, 1 |
| 6 | Bread Board | – | 1 |
| 7 | AAA Cells | – | 1 |
| 8 | Jumpers | – | 1 |
Circuit Diagram
Working Explanation
When the switch is “on” the circuit is completed and turned on the NPN transistor is connected to the base of the PNP transistor and the PNP transistor is activated and charged the capacitor and discharges the capacitor through the LED, this activates the LED on. The capacitor is discharged, the LED is deactivated, then the battery is charged up the capacitor again.
The greater the value of the Capacitor it took time to charge and discharge the capacitor and Led on and off duration can adjust by adjusting the value of the capacitor.
Applications & Uses
There are many applications of the LED blinking circuit just through AAA cells or 1.5V
- Led Blinking Circuits used in Toys for Lightning.
- These Blinking Circuits are used as an indication of any problem in the vehicle or any wear or tear of car parts.
- Blinking Feature used in IoT devices.
- Led Blinking is used for visual sign indication on any highway.
