Led Flasher Circuit

The operation of the LED flasher circuit project is based on 555 timers with few other components. It flashes the LED ON and OFF after regular intervals of time. It can be used as eye of a toy to find the toys in the dark, in events like wedding ceremonies, birthday parties or any other events to grab the attention.The pinouts of the 555 have been explained in the circuit, given below is the pin description of the IC:

Pin Description:

Pin No	Function	Name
1	Ground (0V)	Ground
2	Voltage below 1/3 Vcc to trigger the pulse	Trigger
3	Pulsating output	Output
4	Active low; interrupts the timing interval at Output	Reset
5	Provides access to the internal voltage divider; default 2/3 Vcc	Control Voltage
6	The pulse ends when the voltage is greater than Control	Threshold
7	Open collector output; to discharge the capacitor	Discharge
8	Supply voltage; 5V (4.5V - 16 V)	Vcc

The LED Flasher circuit project here is based on 555 timers. The timer is wired in astable mode which means that its output is a square wave oscillator. The two LEDS are connected in such a way that when one is ON other is OFF and vice versa.

The capacitor C2 charges exponentially through the resistors R1, R2 and the trimpot. When charge of the C2 reaches 2/3 Vcc it stops charging and starts discharging through R2 and trimpot resistance till it reaches 1/3 Vcc.

The pin2 of the IC is for trigger input. When the voltage supplied to pin2 is less than 1/3 of the supply voltage, the output of the lower comparator forces the flip flop to have low logic state. The output has reversing action. In other words, we can say that when the output of the flip flop is LOW, the 555 timer’s output goes HIGH. The LED starts flashing when a voltage between 5V to 15V is applied. By varying the resistance of the potentiometer or trimpot the frequency of the flashing can be changed.