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Mobile cell phone detector (sniffer) circuit diagram: engineering and diploma project
Here is a simple engineering project circuit of handy mobile cell phone detector (sniffer). This pocket-sizedmobile communication detector or sniffer can sense the existence of a mobile device. So it can be used to avoid the use of mobile phones in private rooms, examination halls, etc. It is also useful for detecting the use of mobile phone for s
Contactless telephone ringer circuit
The contact less telephone ringer circuit can produce a ring as well as a visual indication when a call comes. The main advantage is that since there is no direct contact between the phone line and the circuit there is no chance for a loading or disturbance in the telephone line. When the telephone rings 60 Hz AC signal is generated which produces
FM telephone bug
A simple telephone transmitter circuit that is ideal for transmitting the telephone conversation through small distances. The circuit is very simple and uses only few components. The entire circuit can be easily included in the telephone itself or in the junction box. The circuit is powered from the telephone line itself. The transistor Q2 is...
Head phone amplifier circuit
Here is a simple head phone amplifier circuit that can be used to drive your head phone if your music player doesn`t have enough power to drive your head phones. The circuit is straight forward and uses only three transistors. The transistor Q1 (BC 239) and associated components forms a pre amplifier. The transistor pairs Q2 & Q3 (BC 337 & BC...
Ringing phone light flasher
When the telephone rings the line voltage rises to 72 volts. At this time the LED in the opto-coupler glows and the transistor conducts. Due to this the transistor Q1 conducts. This makes the relay ON. The load connected to the relay whether bulb or bell turns ON.
Telephone in use indicator
Here is a simple circuit that can be used as a telephone status indicator. When the telephone is in use (off hook) the transistor Q1 switches ON making the red LED D2 glow. When the telephone is not in use (on hook) the Q1 turns OFF and Q2 turns ON. This makes the red LED D2 off and green LED D3 ON. The circuit is powered from the phone line itsel
Telephone off-hook indicator
The circuit depicted here can be used as an indicator when the telephone receiver is off-hook. The circuit can be in corporated with old telephones that does not have such an indicator. The circuit uses a complementary darling to pair using Q1 (2N3904)and Q2 (2n3906) to sense whether the receiver is off hook and glows a LED to show the condition.
Telephone operated remote
The circuit given below is of a telephone operated DTMF remote. The circuit can be used to switch up to 9 devices using the keys 0 to 9 of the telephone. Digit 0 is used to switch the telephone system between remote switching mode and normal conversation mode. IC KT3170 (DTMF to BCD decoder) is used to decode the DTMF signals transmitted over the
Telephone pickup preampliifer
Here is a simple circuit based on IC uA 741 that can be used to pickup voice from telephone lines without even contacting the line. If a high impedance magnetic core is placed near a telephone instrument or near one of the telephone wires, it picks up inductively both sides of the telephonic conversation without any electrical contact. A preamplif
This is a simple, but very useful circuit that can be used to transmit telephone conversations. When the telephone receiver is on hook the voltage across the lines will be about 48 volts. The preset R7 is so adjusted to obtain a 24. 7 V across between the cathode of D2 and ground. At this voltage the Zener diode D2 will be in breakdown and the tran
Ultra Small Mobile Phone Xenon Photoflash Capacitor Charger With IGBT Driver
The AAT1265 evaluation board provides a platform for the testing and evaluation of the AAT1265 low voltage 2MHz Step-up Regulator The evaluation board demonstrates suggested size and placement of external components to main- tain output voltage regulation for up to 250mA of output current. The external components are selected for small size to sui
AN6591FJM Transmission / Reception Single Chip Pll Ic For Phs Cordless Telephone Panasonic Semiconductor
The AN7158N is an integrated circuit designed for power Amplifier of 7. 5W (16V, 4) output with low noise and low distortion, and it suits TV set with multi-sound. Stereo operation is enabled due to incorporating two Amplifiers on one chip. 12-pin SIL package enabled com- pact and high-densely mounted set. By Panasonic USA
BU8732AKV Codec Ic For Digital Mobile Phone
The BU8872 and BU8872FS are DTMF receiver ICs developed for use in telephone answering machines, and convert 16 different types of DTMF signals into 4-bit binary serial data. In addition to a compact 8-pin DIP BU8872 or 16-pin SSOP BU8872FS package, these receivers feature a wide dynamic range, eliminating the need for an external input Amplifier
H66T32BA CMOS LSI Designed For Use In Door Bell Telephone And Toy Applications
MC33411A 900 MHZ ANALOG CORDLESS PHONE BASEBAND WITH COMPANDER
MC34017A Telephone Tone Ringer Bipolar Linear/I2L
As it is well known, according to power saving regulations, we need to obtain a very low power consumption during standby condition for all equipment continuously powered on the mains. For not saving version of power supply, the standby power consumption is around 9. 0 W (for 100 W power output). When using the MC44608 GreenLine ›› Power supply
PCD3360 PCD3360 Programmable Multi-tone Telephone Ringer
TA31001 Telephone Tone Ringer
TS2418 Telephone Tone Ringer With Bridge Diode
The TS4956 is a complete Audio system device with three dedicated outputs, one stereo Headphone one loudspeaker drive and one mono line for a hands-free set. The stereo Headphone is capable of delivering more than 25 mW per channel of continuous average power into 16, single-ended loads with 0. 3% THD+N from a 5 V power supply. The device functions
DMX Controlled Theatrical Phone Ringer
A four channel DMX512 controlled ringer. The Mk 3 will also incoporate a ringing supply generator, and thus be reproducible by others not in posession of the BT ringing supply Number 7. The ringer is microprocessor controlled, using a Parallax Propeller based chip, specifically the Spin Stamp, part number SSC1-IC, which is a 24 pin packaged...
The Original 2 Phone Link=
This is the circuit that sparked off all the other Link Telephone Intercom designs. Originally designed back in 1996 with heavy duty relays and their contact banks, it was updated late last year with the addition of IC1 in place of a simpler transistor multivibrator, the replacement of all relays and contact banks with optocouplers, and the additi
Privacy Telephone Intercom
The circuit you are about to see is the culmination of some effort at improving the basic Link intercom design. You may think that pulse dialing is `old hat` nowadays, but the exercise of building and testing the Link `P` in this format, and understanding how it all works, is well worth the effort. Not to mention all those out there who have the...
Soft Musical Telephone Ringers
The normal telephone bell, at times (specially during night when one does not want to be disturbed), appears to be quite irritating. The circuit shown here converts the loud sounding bell into a soft and pleasing musical tone. The incoming ring is detected by transistor T1 and components wired around it. In absence of ringing voltage, transistor T
While talking to a distant subscriber on telephone, quite often we feel frustrated when the voice of the distant subscriber is so faint that it is barely intelligible. To overcome the problem, circuit of an inexpensive amplifier is presented here. It can be assembled and tested easily. There is no extra power source needed to power up the...
Telephone line monitors
If you feel that somebody is tampering with your telephone line you might find this little circuit useful. It detects if there is another telephone connected to the line, if there is a short or an open line. Sound and a flashing light will tell you which is the current situation. The speaker is practically cut out during a normal conversation...
Cut Phone Line Detectors
FM Telephone Bugs
Small telephone bug. Listen telephone line on your FM receiver. It is self powered. Small part count. Circuit diagram, schematics, electronics project..
Phone Busy Indicators
It signals that the phone is in use by lighting a red LED. When the phone is not in use, a green LED is lit. It needs no external power and can be connected anywhere on the phone line, even mounted inside the phone. 4. The ring voltage on a phone line is anywhere from 90 to 130 volts. Make sure no one calls while you are making the line...
Telephone Hold Buttons
Telephone line monitors
This nifty little circuit lets you record your phone conversations automatically. The device connects to the phone line, your tape recorder`s microphone input, and the recorder`s remote control jack. It senses the voltage in the phone line and begins recording when the line drops to 5 volts or less. 2. Some countries or states require you to notif
The Link A2B+1 (the Link Telephone Intercom - DTMF version)s
telephone transmitter circuit
Telephone Ringer Circuits
Telephone Surveilance Bug Circuits
Ultrasonic distance finder circuit
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
Digital Signal Integrity
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