Mobile Phone Circuit | Electronic Project Circuits

Posts Tagged ‘mobile phone circuit’

Mobile Bug Detector using CA3130

This handy, pocket-size mobile transmission detector can sense the presence of an activated mobile phone 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. 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. 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 optimize the frequency response.

When the mobile phone 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 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 optimized 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.
Author: D. Mohan Kumar – Copyright: EFY Magazine
Source: http://www.extremecircuits.net/

Be the first to comment - What do you think? Posted by admin - September 6, 2010 at 11:12 pm

Categories: Mobile phone, Telephone Tags: bug detector circuit, CA3130, mobile phone circuit, mobile transmission detector

Solar Cell Phone Battery Charger

I See to this site, Very good centent battery Charger.

Detail::
This little gadget uses a small 3 volt solar cell to charge a 6 volt NiCad battery pack which, in turn, may be used to charge many models of cell phones and other portable devices. The circuit “scavenges” energy from the solar cell by keeping it loaded near 1.5 volts (maximum energy transfer value) and trickle charges the internal battery pack with current pulses. The simple circuit isn’t the most efficient possible but it manages a respectable 70% at 100 mA from the cell and 30% when the cell is providing only 25 mA which is actually pretty good without going to a lot more trouble or using more exotic components.

Be the first to comment - What do you think? Posted by admin - August 1, 2007 at 11:21 am

Categories: Battery charger Tags: Battery charger, mobile phone circuit

mobile phone circuit #7

sony_cm-dx1000(service_bulletin).rar	177 KB	15/11/2548	0:00:00
sony_cmd-c1(service_bulletin).rar	21 KB	15/11/2548	0:00:00
sony_cmd-c1_c8.pdf	567 KB	15/11/2548	0:00:00
sony_cmd-cd18.pdf	637 KB	15/11/2548	0:00:00
sony_cmd-cd5(sm).pdf	511 KB	15/11/2548	0:00:00
sony_cmd-dx1000.pdf	252 KB	15/11/2548	0:00:00
sony_cmd-j6_j26(sm).pdf	1906 KB	15/11/2548	0:00:00
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sony_cmd-mz5(sm).pdf	2128 KB	15/11/2548	0:00:00
sony_cmd-x2000(serv-man).pdf	276 KB	15/11/2548	0:00:00
sony_cmd-x2000(service_bulletin).rar	288 KB	15/11/2548	0:00:00
sony_cmd-z1(service_bulletin).rar	448 KB	15/11/2548	0:00:00
sony_cmd-z1(sm).pdf	289 KB	15/11/2548	0:00:00
sony_smd-z7(sm).pdf	843 KB	15/11/2548	0:00:00
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t2288en.zip	2455 KB	26/9/2544	0:00:00
timeport.zip	2966 KB	26/9/2544	0:00:00
titan_ru.zip	6099 KB	26/9/2544	0:00:00
waptor23.exe