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Telephone handset tone dial encoder
This encoder uses a single contact per key keyboard and provides all other switching function electronically. The diode between terminals 8 and 15 prevents the output going more than 1 volt negative with respect to the negative supply V-
Microcontroller Based Telephone Remote Control Circuit
This device allows you to control remotely any (with suitable add-on expansion boards, up to eight) device, such as lights, water heaters (boiler), air-condition, plant watering, alarms, etc via a relay. By using it you can for example water the garden at your country house from the convenience of your living-room, or you may turn on the water...
DTMF proximity detector
The circuit presented here enables you to detect any object capable of reflecting the IR beam and moving in front of the IR LED photodetector pair up to a distance of about 12 cm from it. The circuit uses the commonly available telephony ICs such as dial-tone generator 91214B/91215B (IC1) and DTMF decoder CM8870 (IC2) in conjunction with...
Heres a small and handy tester circuit for the DTMF IC. It can be assembled on a multipurpose PCB with an 18-pin IC base. One can also test the IC on a simple breadboard. The MT8870 is an 18-pin IC. It is used in telephones and a variety of other applications.
Telephone Intercom - DTMF
This version of the Link uses DTMF tones for dialling both internally between handsets, and externally for outside calls. Remember, in some countries, it is ILLEGAL to simply connect unapproved and untested equipment to Telco lines, so avoid the fine and confiscation of your equipment, and ask nicely? OK ? now, the link A2B as shown has only 2...
DTMF Phone Dialer with PIC16F690 and NTE1690
The circuit uses a NTE1690 DTMF dialer chip and a PIC16F690 microcontroller. Because this is an IP phone and I cannot just send the DTMF tones over the line, the easiest place to plug in the box is between the phone and the handset. The box has two RJ9 ports at the back - one gets connected to the headset's port on the phone, the other to the...
DTMF decoder with voice!
The Talking Phone Dial Monitor detects the tones generated when numbers are dialed on your touch tone telephone and speaks the numbers that were dialed. This verifies that you dialed the correct number and is especially useful when the keypad is not well lighted or if the person dialing cannot see the keypad well for any reason. The...
Telephone Hold Line
The UNIVERSAL HOLD circuit detects the dual tone, multi frequency (DTMF) tone that is generated when the # key is pressed and then activates a circuit that partially loads the telephone line so that the central office thinks a phone is still off hook even after it is hung up. When any phone is again picked up, the hold function is canceled.
Telephone Remote control
Here is a teleremote circuit which enables switching on and off of appliances through telephone lines. It can be used to switch appliances from any distance, overcoming the limited range of infrared and radio remote controls. The circuit described here can be used to switch up to nine appliances (corresponding to the digits 1 through 9 of the...
Remote Control using DTMF
Here is a circuit of a remote control unit which makes use of the radio frequency signals to control various electrical appliances. This remote control unit has 4 channels which can be easily extended to 12. This circuit differs from similar circuits in view of its simplicity and a totally different concept of generating the control signals....
Telephone DTMF decoder Display
The given circuit, when connected in parallel to a telephone, dis- plays the number dialled from the telephone set using the DTMF mode. This circuit can also show the number dialled from the phone of the called party. This is particularly helpful for receiving any number over the phone lines. The DTMF signal generated by the phone on dialling a...
Arduino Producing DTMF Tones
I wanted to teach my Arduino to talk telephone, so I added a HT9000A DTMF chip to produce the familiar "touch tones" (upcoming projects will act upon "heard" DTMF tones, but with a different chip). The output is really low volume, so you may want to plug in amplified speakers or use an input on your stereo. You could build an amplifier
Radio Remote Control using DTMF
Radio Remote Control using DTMF. Here is a circuit of a remote control unit which makes use of the radio frequency signals to control various electrical appliances. This remote control unit has.
DTMF Proximity Detector
A DTMF-based IR transmitter and receiver pair can be used to realize a proximity detector. The circuit presented here enables you to detect any object capable of reflecting the IR beam and moving in front of the IR LED photo-detector pair up to a distance of about 12 cm from it. The circuit uses the commonly available telephony ICs such as dial-to
Telephony Circuits and DTMF Circuits
9-line telephone sharer This circuit is able to handle nine independent telephones (using a single telephone line pair) located at nine different locations, pdf file Bidirectional telephone line simulator without using telephone lines, couple, test and demonstrate all types of telephone equipment such as: answering machine, modem, fax, call record
Adopt the dialing demoder conceptual design of embedded DTMF of MSP430
DTMF dual tone multifrequency The signal is a commonly used signalling in the telephone network, no matter on home telephones, cellular telephones or SPC exchanges, adopt DTMF signal transmission receiving numbers more. DTMF technology can also be used for occasions such as power line carrier communication, etc. It is obvious, DTMF has extensive ap
radio remote control using dtmf circuit
Here we make use of DTMF (dual-tone multi frequency) signals (used in telephones to dial the digits) as the control codes. The DTMF tones are used for frequency modulation of the carrier. At the receiver unit, these frequency modulated signals are intercepted to obtain DTMF tones at the speaker terminals. This DTMF signal is connected to a DTMF-to
DTMF Receiver IC MT8870 Tester
Today, most telephone equipment use a DTMF receiver IC. One common DTMF receiver IC is the Motorola MT8870 that is widely used in electronic communications circuits. The MT8870 isan 18-pin IC. It is used in telephones and a variety of other applications. When a proper output is not obtained in projects using this IC, engineers or technicians need
Device Control Using Telephone
Controlling devices using switches are common. From a few decades controlling devices using remote control switches like infrared remote control switch, wireless remote control switches, light activated switches are becoming popular. But these technologies have their own limitations. Laser beams are harmful to mankind. Some technologies like IR re
DTMF Decoder Circuit For PC
Our DTMF decoder can be powered from a 9V battery or from your parallel printer port. It can detect and display all 16 DTMF digits on your computer screen in real-time. The Window`s program can be placed in the minimize mode and still detect tones while you use your computer to do other things like We are now in the process of adding an DTMF decod
The main system is the user interface and control system. The phone line was chosen as the method of interfacing because it has distinct advantages over other systems in communicating information from a distance. The next image serves as a block diagram for not only the remote access interface but the overall system as a whole. System flow and act
dtmf touch tone decoder using microchip pic microprocessor using pic12f683
DTMF Touch Tone Decoder Using Microchip PIC Microprocessor This project contains the details of using a Microchip PIC12F683 8 bit microprocessor to detect..
telephone dtmf remote control
The circuit is a remotely operated DTMF telephone. The circuit can be used to change up to 9 devices using the keys 0 to 9 phone. Digit 0 is used to switch between the phone system remotely and change the way of normal conversation. IC KT3170 (DTMF to BCD decoder) is used to decode DTMF signals transmitted through the telephone line to the corresp
dtmf decoder interface nokia 1600 headphone pin
Running the Simple MT 8870 Decoder from your Cell Phone the devise can be operated from any type of DTMF tones like Land Lines, Mobiles, Computers, Radio Transmitters that send DTMF tones over the air waves, Ham Radio sets with DTMF built in to them it has a lot of uses. 2). The devise can be connected to any thing that sends DTMF tones and it...
DTMF Control circuit
Control monitoring equipment at a TV repeater site. It had to accept commands sent as DTMF tones over the repeaters audio channel and be able to switch either AV signals or power supply feeds at currents up to 1 Amp. The switching requirements left no option but to use relays and the cheap and easily available BT53 ” style was chosen. As these...
dtmf tone decoder
This project has an impossible requirement or uses parts that are no longer available. It is here for reference or inspiration only. Consider it unsupported . This project displays telephone numbers decoded from tones. Specifically, telephone touchtones. Dual Tone Multifrequency (DTMF) tones. This has nothing to do with CallerID. A microphone pi
The A3425 is a dualoutput-channel, bipolar Switch with each channel comprising a separate complete Hall-effect Sensor circuit with dedicated Hall element and separate digital output for speed and direction signal processing capability. The independent Hall elements (E1 integrated with OUTPUTA, and E2 integrated with OUTPUTB) are photolithographica
BU8872 Dtmf Receiver For Telephones
CM8870 CMOS Integrated DTMF Receiver
The CAMD CM8888 8888-2 is a fully integrated DTMF Transceiver, featuring adjustable guard time, Automatic Tone burst mode, call progress mode, and a fully compatible 8051 8086/8 Microprocessor Interface The CM8888 8888-2 is manufactured using state-of-the-art advanced CMOS technology for low power consumption and precise data handling. The CM8888
CM8888 CMOS INTEGRATED DTMF TRANCEIVER
As part of the DBS 800 System, this Audio signalling processor will provide an inband Tone signalling facility for PMR Radio systems. Signalling systems supported include Selcall (CCIR, ZVEI I, II and III, EEA), 2-Tone Selcall and Dual Tone Multi-Frequency (DTMF) encode. Using a non-predictive Tone decoder and versatile encoders gives the FX803 th
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...
DIY HV Variable Capacitor
DIY PMA Alternator Plans
Digital Signal Integrity