Cellphone Detector

By | November 1, 2017

*Introduction*With the advancement in communication technology, cell phones now are the most common electronic equipment. It transmits and receives signals in the frequency range of 0.9GHz to 3GHz. The circuit below detect the presence of an activated cell phone when it detects these signals. The principle behind the project is the idea of using the Schottky diode to detect the signals.*Operation*The detector circuit consists of an inductor, diode, a capacitor and a resistor. In normal condition, when there is no RF signal, the voltage across the diode will be negligible. Even though this voltage is amplified, yet the output voltage is less than the reference voltage which, is applied to the inverting terminal of the comparator. Since the voltage at non inverting terminal of the OPAMP is less than the voltage at the inverting terminal, the output of the OPAMP is low logic signal.Cellphone-Detector.pngWhen a mobile phone is present near the circuit, the RF signal from the mobile induces a voltage in the inductor. This AC signal is then rectified through the Schottky diode. The output signal is filtered by the capacitor C1.This input voltage is amplified by the common emitter transistor. The output voltage is such that it is more than the reference output voltage. The output of the OPAMP is thus a logic high signal and the LED starts glowing, to indicate the presence of a mobile phone.*Testing ang Design Procedure*Final-Project (1).png

*Conclusion*When LED is on, the circuit indicates that it detects a signal. When it is off, it does not. The output of the circuit, indicated in the net1012, is the required amount of voltage needed to turn the LED on. This proves that the circuit can detect a signal when it is placed nearby a cell phone.Project Link: http://schematics.com/embed/cellphone-detector-36647 “http://www.electronicshub.org/cell-phone-detector-circuit/ (Cellphone Detector)”:http://www.electronicshub.org/cell-phone-detector-circuit/

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