Call Indicator

Summary of the circuit-

1. Whenever you have a new call this project will provide you a visual warning.

2. This circuit is very useful at noisy places where it’s difficult to hear the ringtone.

3 When you are fed up of incoming calls and need silence but cannot ignore ringtone, this circuit would be useful. You will get new call information by a blink of LED.

4. You need to put your mobile close to this project and LED will blink when you have a call. This project will detect the radiation coming out from your mobile.

Principle behind Circuit-

This circuit is quite pocket-friendly and at the same time, simple to build. Components like 555 timer, capacitor, transistors, inductor and few resistors are needed to construct the circuit.

When a new call comes, this circuit will provide you an optical effect by flashing an LED. It can be useful in situations where you can’t keep your phone on ringing mode like while working in the office or at home when somebody is sleeping or even when you don’t wish to hear the tone and need some silence. This circuit can also be used in places where there is a lot of noise due to which you are not able to hear the ringtone of your cell phone.

When someone calls you, the transmitter inside your cell phone is triggered and about 900MHz of frequency is transferred by it. Now the inductor L1 catches this frequency produced by the transmitter of mobile and passes it to transistor T1,that comes into active state. Now by the collector end of transistor, IC1 will receive the input through pin 2. As IC1 gets triggered, the LED which is coupled with pin 3 if IC1 will flash and you’ll get to know that you have a call.

Components required building the circuit-

(IC1) NE555

Resistor

R1 1M

R2 3.9K

R3 100k

Capacitor

C1, C3 0.01uF

C2 220uF