CELL PHONE DETECTOR MOBILE BUG

This handy mobile bug or cell phone detector, pocket-size mobile transmission detector or sniffer can sense the presence of an activated mobile cellphone from a distance of one and-a-half metres. So it can be used to prevent use of mobile phones in examination halls, confidential rooms, etc. It is also useful for detecting the use of mobile phone for spying and unauthorised video transmission.

The circuit can detect both the incoming and outgoing calls, SMS and video transmission even if the mobile phone is kept in the silent mode. The moment the bug detects RF transmission signal from an activated mobile phone, it starts sounding a beep alarm and the LED blinks. The alarm continues until the signal transmission ceases.

Cell Phone Detector circuit diagram

An ordinary RF detector using tuned LC circuits is not suitable for detecting signals in the GHz frequency band used in mobile phones. The transmission frequency of mobile phones ranges from 0.9 to 3 GHz with a wavelength of 3.3 to 10 cm. So a circuit detecting gigahertz signals is required for a mobile bug.

Here the circuit uses a 0.22μF disk capacitor (C3) to capture the RF signals from the mobile phone. The lead length of the capacitor is fixed as 18 mm with a spacing of 8 mm between the leads to get the desired frequency. The disk capacitor along with the leads acts as a small gigahertz loop antenna to collect the RF signals from the mobile phone.
Cell phone RF radiation detector Video

and another video from Sufyan Ghori

Op-amp IC CA3130 (IC1) is used in the circuit as a current-to-voltage converter with capacitor C3 connected between its inverting and non-inverting inputs. It is a CMOS version using gate-protected p-channel MOSFET transistors in the input to provide very high input impedance, very low input current and very high speed of performance. The output CMOS transistor is capable of swinging the output voltage to within 10 mV of either supply voltage terminal.

Capacitor C3 in conjunction with the lead inductance acts as a transmission line that intercepts the signals from the mobile phone. This capacitor creates a field, stores energy and transfers the stored energy in the form of minute current to the inputs of IC1. This will upset the balanced input of IC1 and convert the current into the corresponding output voltage.

Capacitor C4 along with high-value resistor R1 keeps the non-inverting input stable for easy swing of the output to high state. Resistor R2 provides the discharge path for capacitor C4. Feedback resistor R3 makes the inverting input high when the output becomes high. Capacitor C5 (47pF) is connected across ‘strobe’ (pin  and ‘null’ inputs (pin 1) of IC1 for phase compensation and gain control to optimise the frequency response.

When the cell phone detector signal is detected by C3, the output of IC1 becomes high and low alternately according to the frequency of the signal as indicated by LED1. This triggers monostable timer IC2 through capacitor C7. Capacitor C6 maintains the base bias of transistor T1 for fast switching action. The low-value timing components R6 and C9 produce very short time delay to avoid audio nuisance.

Assemble the cell phone detector circuit on a general purpose PCB as compact as possible and enclose in a small box like junk mobile case. As mentioned earlier, capacitor C3 should have a lead length of 18 mm with lead spacing of 8 mm. Carefully solder the capacitor in standing position with equal spacing of the leads. The response can be optimised by trimming the lead length of C3 for the desired frequency. You may use a short telescopic type antenna.
Use the miniature 12V battery of a remote control and a small buzzer to make the gadget pocket-size. The unit will give the warning indication if someone uses mobile phone within a radius of 1.5 meters.
Check the related posts for more mobile phone detectors.

555 datasheet

IC CA3130 datashee

cellphone jammer circuit diagram for usa

A beautiful diy gsm jammer or mobile cell phone jammer schematic diagram for use only in GSM1900 with frequency from 1930 MHz to 1990 MHz. The GSM1900 mobile phone network is used by USA, Canada and most of the countries in South America.

Mobile cellphone jammer circuit diagram

This cell phone jammer is not applicable for use in Europe, Middle East, nor Asia.
The GSM jammer circuit could block mobile phone signals which works on GSM1900 band, also called DCS. For more cell phone jammers check the related posts.

cell phone jammer

Simple Cell Phone Jammer

A “Cell Jammer” is just way of saying “Dirty Transmitter” which happens to transmit within the Cellular Phone Bands. Reality is, the dirtier the better. The 555 timer [8 pin] IC simply makes a noise. It’s coupled via C4 [electrolytic] to modulate the MRF transistor oscillator. With C1 set at roughly 1/3rd, you will be close to 900 MHz. By sweeping the C1 trimmer capacitor, you can swing the output frequency from 800 MHz to 2 GHz with the transistor and values shown. You could replace the 555 chip with an electret microphone and listen to yourself talk on a scanner, so the unit could easily couple as a UHF Bug. Instead of a single Tapped Coil, I’ve used two molded inductors for ease of construction.Values for C1,C2,L1,L2 are critical for the frequency range. You might want to build the unit into a metal box, add an on/off switch in the batteries + line, and maybe even add a LED. Connect an old 800 MHz cell phone antenna to C5. Would you believe the whole thing can be built on top of the 555 IC itself when using surface mount components, and the lot will fit onto a nine volt battery clip. Output is reasonably good, although the current drain is a bit high, so a new 9 Volt battery will only run about an hour, [if you are lucky]. The “Cell Kill Distance” is around 10 – 15 feet, ample for most purposes.