Phone calls phone calls lights kit can be used to sense the GSM signal display, sensing distance up to 1 m, is a very interesting DIY module.
Supply voltage: 3 to 12V Sensing distance: about 1 m PCB board size: 2.2cm * 2.8cm Scope: GSM mobile phone signal, for CDMA phones are useless Note: This is a DIY kit, you need to assemble it.
The circuit theory:
The main circuit is amplified antenna sensor signal circuit and circuit. Sensing signal through the antenna 3 to S8050 transistor amplifier to drive the LED, so that light up. When no signal is detected, no calls or no GSM phones, LED circuit is not only detects the signal to light up LED.
Inductance of production:
Inductance 0.25 to 0.5MM enameled available in pen core above can be around 5-10 laps. After a good round with a blade to scrape paint inductor 2, so we go soldered to the board.