Phone Circuits
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Built quickly from the parts found on my home lab, seemed to work on short test with telephone line simulator and line connected to PBX, I have received a report that this circuit works well in Australia This circuit is a simple circuit which prevents.... -
A telephone uses an electric current to convey sound information from your home to that of a friend. When the two of you are talking on the telephone, the telephone company is sending a steady electric current through your telephones. The two telephones,.... -
How to connect up some lights so that when the phone rings, they flash. This is very useful in a situation were there is lots of noise and it is impossable to hear the phone, such as a workshop. Here is such a device. The ring detect part of this circuit.... -
Usually a single telephone is connected to a telephone line. If another telephone is required at some distance, a parallel line is taken for connecting the other telephone. In this simple parallel line operation, the main problem is loss of privacy besides.... -
This circuit is able to handle nine independent telephones (using a single telephone line pair) located at nine different locations, say, up to a distance of 100m from each other, for receiving and making outgoing calls, while maintaining conversation.... -
The interval between rings can be lengthened or shortened by varying the value of the 1 Meg resistor. The 70 volt/ 30 Hz ring voltage is produced from the 120 volt side of a small 12. 6 VAC power transformer (Radio Shack 273-1365). Both capacitors connected.... -
This is a similar circuit to the above and provides a 4 LED bar graph indicating the voltage of a common 3.6 volt Lithium - Ion recharable cell phone battery. The reference voltage is provided by a TL431 programmable voltage source which is set to 3.9 volts.... -
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.... -
You are asking how to connect up some lights so that when the phone rings, they flash. This is very useful in a situation were there is lots of noise and it is impossable to hear the phone, such as a workshop. Here is such a device. The ring detect part of.... -
This circuit was designed to detect when a call is incoming in a cellular phone (even when the calling tone of the device is switched-off) by means of a flashing LED. The device must be placed a few centimeters from the cellular phone, so its sensor coil L1.... -
This Photo Instructable shows how to use two old phones as a cheap intercom between Point A and Point B. Might be useful between the house and the sh.... -
This works in a way that the phone line won`t stay busy while the LEDs are connected and when you pick up the phone, the light goes off and allow you to use your phone normally. hello. u sadi that ur phone delivers 48 v DC n when phone rings, it delivers 96.... -
One is in a leather bag and is model EE-8-A. One or more is in a canvas bag and is EE-8-B. All have handsets with the butterfly push-to-talk lever. The -B model does have an original handset and cord. These have been tested in both LB and CB modes and work.... -
This circuit produces a ringing sound similar to that made by more recent telephones. It consists of three almost identical oscillators connected in a chain, each generating a squarewave signal. The frequency of each oscillator depends on the RC combination:.... -
A long time ago when telephones were so simple almost nothing could go amiss from an electrical point of view, Telecom operators installed surge protection on all telephone lines exposed to storm risks. Paradoxically, now that we are hooking up delicate and.... -
With the aid of an (old) moving coil instrument it is very little effort to make a simple voltmeter that, at a glance, indicates the status of a telephone line. Because the input impedance of this circuit is very high, there is no problem in having it.... -
If you are lucky enough to have a big house, a large garden, and small children, this project just might interest you. It`s actually a telephone ringer capable of making any mains-powered device work from the ringer of your fixed line. With it, you will be.... -
The phone is a Siemens S65. The official charger that came with the phone says 5V at 420mA. Because these things do not always actually deliver what is printed on them I measured the voltage myself. This is actually quite hard with the tiny contacts on the.... -
A portable phone charger for a Siemens mobile phone. Since I don`t use that phone anymore and recent phones can usually be charged with a USB connector I built a new version of the charger. This time with a proper PCB, a USB connector and a higher current....
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This is an amplified telephone line tap, which is designed to be minimally invasive. The interconnect to the phone line has a large input impedance, and is electrically isolated from the main electronics of the circuit. I designed this for use with a DTMF.... -
The heart of the circuit is IC1, General Instrument`s AY-3-1350 melody-synthesizer IC. IC2 is a TCM1512 telephone ring detector IC that is powered by the telephone line. The circuit`s operation begins when IC2 senses a ring pulse on the telephone line. The.... -
Pulse telephone 160 168 controller circuit is shown as above, the controller can be installed on the phone or on the switchboard of the trunk. It can effectively prevent the others to freely dail 160, 168. D1 ~ D4 use 1N4004, the rest diode use 1N4008. Q1,....
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This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of.... -
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.... -
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.... -
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.... -
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.... -
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,.... -
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.... -
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.... -
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.....
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