Mobile Incoming Call Detector Circuit is smart project.
Detect incoming call and make LED light up.
Circuit is good for noisy places where ringtone is hard to hear.
Catch RF signal from phone when call comes.
Use LC circuit, transistor, 555 timer to turn ON LED.
Circuit runs on 6V battery and is useful and save power.
Circuit Working:
Parts List:
| Component | Specification | Quantity |
|---|---|---|
| Resistors (All resistors are 1/4 watt unless specified) | 100k, 3.9k, 1M | 1 each |
| Capacitors | Polyester 100nF | 2 |
| Electrolytic 220µF 25V | 1 | |
| Semiconductors | IC 555 Timer | 1 |
| Transistor BC547 | 1 | |
| Diode 1N5819 | 1 | |
| LED any 5mm, 20mA | 1 | |
| Inductor 150 turns of 36 SWG enameled copper wire on a 5mm diameter plastic former | 1 | |
| Battery 6V | 1 |
When phone gets call it sends RF signal.
Signal makes small voltage on inductor L1.
L1 and C3 make tuned circuit to catch mobile signal.
Signal goes to transistor Q1 and make it stronger.
Strong signal goes to 555 timer IC1.
Timer turn ON LED for short time to show incoming call.
LED stay ON while phone get signal.
Diode D1 protect circuit from wrong voltage.
R1, R2 and R3 set right current.
C1 and C2 remove noise and keep circuit steady.
Formulas:
To make our own Simple Mobile Incoming Call Detector we can use these formulas:
LC Resonance Frequency:
f = 1 / (2 * π * √(L * C))
where,
- f is the frequency
- L is the coil inductance
- C is the capacitor value
Set circuit to around 900 to 1800 MHz which is mobile signal range.
T = 1.1 * R3 * C1
where,
- T is how long LED stays ON
- R3 is the resistor
- C1 is the capacitor
Make T long enough so LED is easy to see when call comes.
How to Build:
To build a Mobile Incoming Call Detector Circuit follow the below mentioned steps for connections and assembling:
- Collect all parts as shown in circuit diagram.
- Connect pin 1 of IC1 to GND.
- Connect pin 2 of IC1 between R1 and R2.
- Connect pin 3 of IC1 between LED1 and D1 through C2.
- Connect pin 4 and pin 8 of IC1 to +6V supply.
- Connect pin 6 and pin 7 together.
- Connect C1 from pin 6 to GND.
- Connect R3 from +6V to pin 7.
- Collector of Q1 goes to one side of R1.
- Other side of R1 goes to base of Q1 and C3.
- Emitter of Q1 goes to GND.
- One end of L1 goes to C3 and other end goes to GND.
- Connect +6V battery to positive side and negative to GND.
Conclusion:
This Mobile Incoming Call Detector Circuit helps see when phone gets call using RF signal.
It is very helpful when we cant hear the ringtone.
Tuning LC circuit makes it more sensitive.
Circuit is made with easy parts and is very useful device.