Friday, January 10, 2014

Telephone Call Recorder

Today telephone has become an integral part of our lives. It is the most widely used communication device in the world. Owing to its immense popularity and widespread use, there arises a need for call recording devices, which find application in call centres, stock broking firms, police, offices, homes, etc. Here we are describing a call recorder that uses very few components. But in order to understand its working, one must first have the basic knowledge of standard telephone wiring and a stereo plug.

Telephone Call Recorder Circuit diagram

In India, landline telephones primarily use RJ11 wiring, which has two wires—tip and ring. While tip is the positive wire, ring is the negative one. And together they complete the telephone circuit. In a telephone line,  voltage between tip and ring is around 48V DC when handset is on the cradle(idle line). In order to ring the phone for an incoming call, a 20Hz AC current of around 90V is superimposed over the DC voltage already present in the idle line.  The negative wire from the phone line goes to IN1, while the positive wire goes to IN2. Further, the negative wire from OUT1 and the positive wire from OUT2 are connected to the phone. All the resistors used are 0.25W carbon film resistors and all the capacitors used are rated for 250V or more.
The negative terminal of ‘To AUX IN’ is connected to pin 1 of the stereo jack while the positive terminal is connected to pins 2 and 3 of the stereo jack. This stereo jack, in turn, is connected to the AUX IN of any recording device, such as computer, audio cas-sette player, CD player, DVD player, etc. Here we shall be connecting it to a computer. When a call comes in, around 90V AC current at 20Hz is superimposed over the DC voltage already present in the idle line.
Telephone Call Recorder Mic
This current is converted into DC by the diodes and fed to resistor R1, which reduces its magnitude and feeds it to LED1. The current is further reduced in magnitude by the resistor R2 and fed to the right and left channels of the stereo jack, which are connected to the AUX IN port of a computer.  Any audio recording software, such as AVS audio recorder (available at:, Audacity audio recorder (, or audio recorder (, can be used to record the call. When a call comes in, one needs to launch the audio recording software and start recording.
Telephone Call Recorder
For phone recording, simply connect the stereo jack to the AUX IN port of the PC. Install the  Audacity audio recorder (different versions are available for free for different operating systems at on your PC. Run the executable  Audacity file. In the main window, you will find a dropdown box in the top right corner. From this box, select the AUX option. Now you are ready to record any call. As soon as a call comes in, press the record button found in the Audacity main window and then pick up the telephone receiver and answer the call. Press the stop button once the call ends. Now go to the file menu and select the ‘Export as WAV’ option and save the file in a desired location.

You may change the value of resistor R2 if you want to change the output volume. You can use a variable resistor in series with R2 to vary the volume of the output. The recorded audio clip can be edited using different options in the  Audacity software. You can assemble the circuit on a general-purpose PCB and enclose it in a small cabinet. Use an RJ11 connector and stereo jack for connecting the telephone set and computer (for call recording). Telephone cords can be used to connect to the phone line and the circuit. Use of a shielded cable is recommended to reduce disturbances in the recording. These can also be reduced by increasing the value of R2 to about 15 kilo-ohms.
EFY note. Audacity recording software is included in this month’s EFY-CD under ‘Utilities’ section.



For total output power of cell phone jammer

For total output power of cell phone jammer is about 0.5W
The definition of the object of study (as a body of two titles, the fourth Times New Roman, bold, left empty word, the same below). China PTAC is the countrys largest mobile phone distributors, sales of mobile phones more than 40 million per year, accounting for almost half of the country. × × Logistics Co., Ltd. is the countrys largest mobile phone carrier, specializing in China PTACs mobile phone distribution business, and its mode of operation on behalf of the logistics of Chinas mobile phone model. (Times New Roman, line spacing, 20 lbs). Characteristics (of the people on the phone the logistics needs of the three title as the text, using the small 4 Times New Roman, bold, left empty word, the same below). It is according to the corresponding standard and specification of cell phone jammer .
The rise of mobile logistics for manufacturers and agents to provide quality transportation platform. Can send and receive MMS from "Big Brother" had only limited to the basic call functions, and today, listen to MP3 music, wireless Internet and even can be used for camera phone, regardless of the function how to increase, what changes shape, it is a mobile phone, you need to logistics service providers connected to the identity of third manufacturers and consumers by the manufacturer or distributor does not appear to bear all of the roles of sales logistics, third-party logistics service providers can play a role irreplaceable. However, the development of the logistics industry, logistics service providers as soon as possible to achieve the integration of logistics resources.According to the nature of the work divided into several departments, organizational structure and reasonable. Each department are relatively independent, but related to each other, very close link between the lack of a part of the whole work is completed. So the flow of information between departments maintain the top priority.
Nokia is a mobile communications products to multinational corporations, headquartered in Finland, the global workforce of about 58,800 people, is a global leader in mobile communications industry. Nokia is listed in Helsinki, Finland, United Kingdom, London, Stockholm, Sweden, France, Paris, Frankfurt, Germany and the United States, New York, and shareholders all over the world. Nokias history began in 1865, a wood pulp factory. In 1967, the main production of cardboard Nokia, the Finnish rubber factory mainly produces sets of boots, and Finnish Cable Works jointly for the Nokia Group, the business covers several areas, including paper, chemical, rubber, etc.. Nokias telecommunications sector is the Finnish Cable Works started in the Electronics Division was established in 1960.

Thursday, January 9, 2014

Little Door Guard

If some intruder tries to open the door of your house, this circuit sounds an alarm to alert you against the attempted intrusion. The circuit (Fig. 1) uses readily available, low-cost components. For compactness, an alkaline 12V battery is used for powering the unit. Input DC supply is further regulated to a steady DC voltage of 5V by 3-pin regulator IC 7805 (IC2).

Fig. 1: Circuit of the door guard

Circuit of the door guard

Assemble the unit on a general-purpose PCB as shown in Fig. 4 and mount the same on the door as shown in Fig. 3. Now mount a piece of mirror on the door frame such that it is exactly aligned with the unit. Pin configurations of IC UM3561 and transistors 2N5777 and BC547 are shown in Fig. 2.

Fig. 2: Pin configurations of UM3561 and transistors 2N5777 and BC547

UM3561 and transistors

Initially, when the door is closed, the infrared (IR) beam transmitted by IR LED1 is reflected (by the mirror) back to phototransistor 2N5777 (T1). The IR beam falling on phototransistor T1 reverse biases npn transistor T2 and IC1 does not get positive supply at its pin 5. As a result, no tone is produced at its output pin 3 and the loudspeaker remains silent. Resistor R1 limits the operating current for the IR LED.
When the door isopened, the absence of IR rays at phototransistor T1 forward biases npn transistor T2, which provides supply to  positiveIC1. Now 3-sirensound generator IC UM3561 (IC1) gets power via resistor R5. The output of IC1 at pin 3 is amplified by Darlington-pair transistors T3 and T4 to produce the alert tone via the loudspeaker.

Fig. 3: Back view of the door assembly

Back view of the door assembly

Rotary switch S2 is used to select the three preprogrammed tones of IC1. IC1 produces fire engine, police and ambulance siren sounds when its pin 6 is connected to point F, P or A, respectively.

Suggested enclosure
Fig. 4: Suggested enclosure with major components layout


The technology development of cell phone jammer has been finished

The technology development of cell phone jammer has been finished.
This mainly refers to the use of 25 ~ 100 W-class CO2 laser to X-Y table system-based laser processing machine models, but also the use of Nd YAG laser and galvanometer integrated machining. It can be carved, including engraving, cutting, engraving, embroidery and cutting. This has a variety of laser processing machine, the price is low, wide use, the characteristics of suitable conditions, the annual output of 6,000 units, which can be used in seals, flexible plates, gifts, advertising, printing cards, crafts and industrial non-metallic products, and on the horn, glass, plastic, rubber, wood products, plastics, fabrics, leather and other materials for laser processing. Because of this processing machine with computer typesetting, self-control, non-contact processing, fast (other than manual processing methods or faster), high intelligence, and other unique advantages of easy operation, it accounted for the majority of the domestic market and exported to Middle East, Southeast Asia, South America, Eastern Europe and Africa, popular with users. The technology development of cell phone jammer will enhance the quality of cell phone jammer .
Production of X-Y table models, high-profile companies in Zhejiang Boye Laser, Guangdong Yue Ming Wuhan Golden Laser Laser and other companies, the rapid rise of the formation of a laser processing machine of this type of production patterns. Currently Boye laser has been built 35000m2 plant, Golden Laser built a 10 000 m2 factory, Yueming laser not only further expand the production capacity of origin, established a branch in Shanghai. In addition to carving this type of flexible rubber, bamboo, it can also be laser-cut clothing, leather, embroidery and other processing products of these enterprises to upgrade and promote the market development. The technology development will improve the manufacturing quantity of cell phone jammer everyday.
These enterprises now will be feeding and rewinding, raw vacuum adsorption, automatic camera positioning, double cropping and other techniques to be applied gradually, the laser processing equipment can be integrated into automated garment production line operations, the product of intelligent upgrade. It is worth mentioning that the rapid development of laser engraving machine is one of the products, it is in the glass by laser-induced formation of burst point of the body composition of white three-dimensional laser light scattering images, this technology has recently made further development. Unit has developed a domestic color laser technology have played in the vitreous body red, orange, yellow, blue, purple and other color patterns, and soon the product will be put on the market, it will add luster to laser products. The technology improvement of cell phone jammer will increase the manufacturing ability of cell phone jammer .
Remanufacturing is the product life cycle theory as a guide for engineering practice. Equipment, feasibility studies, design, manufacture, use, maintenance and recovery of all costs are known as life-cycle cost, the traditional emphasis on the equipment, only the "first half", (this period only 20% to 40% of the cost), and often overlooked, "later life", that the use, maintenance and end of life costs.

Friday, December 27, 2013

IR Remote Control Tester

Here’s a simple, low cost, and easy to construct infrared remote control tester. The tester is built around an easily available infrared receiver module (TSOP 1238).

 IR Remote Control Tester Circuit diagram:

Schematic diagram of IR remote control tester
Normally, data output pin 3 of the IR receiver module is at a high level (5 volts)and as such driver transistor T1 is in cut-off state. Whenever the IR receiver module receives a valid (modulated) infrared signal, its data output pin goes low in synchronism with the received infrared bursts. As a result, transistor T1 conducts during negative pulse period and the.LED blinks to indicate reception of signals from the remote such as TV remote control. A miniature active buzzer is connected at the collector of transistor T1 for audio indication.

Proposed enclosure with front-panel

The 5V DC for energizing the circuit is directly derived from the 230V AC mains supply. Unlike the conventional resistive voltage divider, a capacitive potential divider is used here, which does not radiate any heat and makes the tester quite compact. Another advantage of this tester is no false triggering due to the ambient light or electronic ballast-operated tubelights. A suggested enclosure for the circuit is shown in Fig. 2.
Source :

Thursday, December 26, 2013

Touch Sensitive Light Dimmer

With IC SLB0586A from Siemens you can build a simple touch light dimmer circuit that will allow you to adjust the lamp intensity. Together with a TIC206D triac, it enables smooth regulation of light intensity from a bulb of 10W – 400W. A coil of 100µH/5A is required to suppress switching noise.

The voltage supply is obtained through R2, C2, D1 and C3 and is about 5.3V below the network potential. The touch sensor that is used to drive the IC is connected at pin 5 through two 4.7MΩ resistors, R5 and R6, in order to ensure user security.

In the adjustable touch lamp schematic we can see three selection connection , for selecting one of three modes of the IC. When the B connection is used, the light will always be ON at the last level that we used. With A or C connection the light will be ON at the minimum intensity. With B or C, the purpose of regulation is reversed with each use.

Schematic of the adjustable light with touch sensor
Circuit Project: Touch light dimmer circuit
Touch Sensitive Light Dimmer Circuit Diagram

When the sensor is touched for a short period of time (50 – 400 ms), the lamp will be ON or OFF. If the sensor is touched for a longer period of time it will start the regulation process. Warning! This touch light dimmer circuit has some points where lethal 220V is present, please do not try this project if you are not qualified.

Wednesday, December 25, 2013

Simple Infra red Receiver

This very simple infra-red receiver is intended to form an infra-red remote control system with the simple infra-red transmitter described in this site. The system does not use any kind of coding or decoding, but the carrier of the transmitter is modified in a simple manner to provide a constant switching signal. Since the receive module, IC1, switches from low to high (in the quiescent state, the output is high) when the carrier is received for more than 200 milliseconds, the carrier is transmitted in the form of short pulse trains. This results in a pulse at the output of the receiver that has a duty cycle which is just larger than 12.5%. The carrier frequency used in the system is 36 kHz, so that the output frequency of IC1 is 281.25 Hz.

Infra-red Receiver Circuit diagram :

This signal is rectified with a time constant that is long enough to ensure good smoothing, so that darlington T1 is open for as long as the received signal lasts. A drawback of this simple system is that it may pick up signals transmitted by another infra-red (RC5) controller. In this case, only the envelopes of the pulse trains would appear at the output of T1. This effect may, of course, be used intentionally. For instance, the receiver may be used to drive an SLB0587 dimmer. Practice has shown that the setting of the SLB0587 is not affected by the RC5 pulses. The receiver draws a current of about 0.5 mA.

Source :