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This is a circuit for emergency lighting with LEDs that uses electricity from the telephone line . Generally the phone line has a DC voltage 48V and somewhere around 20 mA , and when the phone rings , the voltage rises to 96V AC . This works in a way that the phone line will not be busy while the LEDs are turned on and when you pick up the phone , the light goes off and lets you use your phone normally .  Emergency Light using Phone Line Circuit Diagram

As we know now a days the main problem is charging of a cell phone when we haven't electricity . And this problem is getting bigger when we have more than one cell phone. So here is the circuit which can be solve our problem for charging more than One cell phone. This circuit of the double DC cell phone charger was successfully tried. The required voltages for the operating of this circuit is 12V DC from a battery source.The transistor T1 which we are using is PnP transistor.The general purpose of this transistor is power application e.g driver stages.The IC1 (7805) is a voltage regulator ic which we are using in this circuit. Parts List R1 = 0.1 Ohms 2 watt, R2 = 2 Ohms 2 Watt R3 = 3 Ohms 1 watt C1 = 100uF/25V C2 = 0.1 disc T1 = BD140 D1 = 1N5408 IC1 = 7805

This is a simple cell phone detector circuit diagram , this is a pocket-size mobile transmission detector or sniffer can sense the presence of an activated mobile cellphone from a distance of one and-a-half meters. 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 unauthorized video transmission. Sourced: EFY  Simple Cell Phone Detector Circuit Diagram  

This cell-phone-controlled audio/ video mute switch is highly useful in automobiles. The circuit automatically disconnects power supply to the audio/video system whenever the mobile handset is lifted off the holder for making or receiving a call. You can use any readily available cell-phone holder with some mi-nor alterations or fabricate it yourself as shown in Fig. 1.  Fig. 1: Proposed cell-phone holder   The circuit is wired around IC LM555 (IC1), the CMOS version of timer NE555, as shown in Fig. 2. IC1 is used as a medium current line driver with either an inverting or non-inverting output. It can sink (or source) current of up to 50 mA only, so take care while handling it. The audio/video system is connected to the circuit via normally opened (N/O) contacts of the relay.   Fig. 2: The circuit of the cell phone-controlled audio/video mute switch   When the cell phone is in its holder, LDR1 does not receive any light from white LED1 and its resistance is high. ...

Circuit showing a mobile phone jammer . 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. 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.  Circuit Diagram  

This battery charger circuit is for Sony Ericsson standard batteries, Li-Polymer type, with a nominal voltage of 3.6V and a capacity of 900mAh. But you can also charge Nokia batteries as well. Charging lithium cells is fairly straightforward. You generate a well regulated voltage and ensure the charging current is sufficiently low so as not to cause overheating problems. Also, when the correct terminal voltage as been attained, it is important to shut down the charging process at that point. The circuit consists of three main sections:   A 5V DC constant voltage supply, which serves as the charging source for the mobile phone battery. Mains voltage is transformed via T1. After rectification and smoothing, via BR1/ C1, about 14V DC is delivered to IC2, which is a 1A 5V regulator. The regulator output delivers the charging current to the mobile phone battery via current limiting resistor R1 and via relay contacts RLA2. Fuse FS1 provides protection in the event of excess current ...

LG has officially announced its latest Android phone – LG G2 . If you’re curious, let’s go on checking what features have been equipped in the smartphone as the successor to last-year LG Optimus G. LG G2 is LG’s latest flagship Android smartphone that measures 138.5 x 70.9 x 8.9mm. As we can see from the images, the smartphone features ultra narrow bezel design, and runs on Google Android 4.2.2 mobile operating system, and comes with a Qualcomm Snapdragon 800 2.26GHz quad-core processor, 2GB LPDDR3 RAM, 32GB internal storage, 5.2-inch Full HD IPS display with 1920 x 1080 pixels resolution, 2.1-megapixel front facing camera and 13-megapixels rear camera with optical image stabilizer, 8x digital zoom, sapphire crystal glass lens and multi-point autofocus. Moreover, the Android phone also has dual speakers, micro USB, GPS with A-GPS and GLONASS, 3000mAh rechargeable battery and more. Apart from that, LG G2 supports GSM/EDGE, HSPA+42Mbps/HSPA+21Mbps, and LTE networks. LG G2 Android phone ...