Phone Circuits
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The 220-240V AC mains source is stepped down to 9V AC by transformer X1. The transformer output is rectified by diodes D1 through D4 connected in bridge configuration and the positive DC source is straightly wired to the charger`s output contact, while the.... -
Telephone ring tone generator circuit, built with only several components. It generates simulated telephone ring tone and requires 4.5V DC to 12V DC voltage.. -
A simple electronic circuit project is discussed here that may be built by any school student for displaying in a school fair science exhibition. The proposed circuit is a high gain opamp amplifier which detects slightest of RF disturbance that might be.... -
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.... -
FM Telephone Bug. Here is a simple transmitter that when connected to a phone line, will transmit anything on that line (execpt the dial tone) to any FM radio. The frequency... -
Wireless Telephone Bug. Here`s a neat little project that will allow you to monitor your phone line as soon as your phone is off hook. You can use a regular FM broadcast band radio... -
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.... -
Multipurpose Circuit for telephone. This add-on device for telephones can be connected in parallel to the telephone instrument. The circuit provides audio-visual indication of on-hook,... -
Off line Telephone tester. Here is a circuit of an off-line telephone tester which does not require any telephone line for testing a telephone instrument. The circuit is so simple that... -
Telephone Headgear. Acompact, inexpensive and low component count telecom head- set can be constructed using two readily available transistors and a few other electronic... -
Telephone line based audio muting and light on circuit. Very often when enjoying music or watching TV at high audio level, we may not be able to hear a telephone ring and thus miss an important incoming phone... -
Telephone Ringer using 556 dual timers. Using modulated rectangular waves of different time periods, The circuit presented here produces ringing tones similar to those produced by a telephone. The... -
The Link Telephone Intercom. The Link circuitry is simple and efficient, employing just two ICs, half a dozen transistors, and a handful of garden variety components. It all runs on 12... -
Two line intercom plus a telephone changeover switch. The circuit presented here can be used for connecting two telephones in parallel and also as a 2-line intercom. Usually a single telephone is connected to a... -
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.... -
The telephone ring generator shown below generates the needed high voltage from a simple switching mode power supply (SMPS) which employs a CMOS Schmitt Trigger square wave oscillator, 10 mH inductor, high voltage switching transistor (TIP47 or other high.... -
Without any USB to phone battery charger circuit we can charging phone battery using port on USB computer, but it will quickly damage the phone battery, and the battery will bulge. Because the voltage which was issued on usb is 5 volts, while the.... -
A wonderful diy gsm jammer otherwise cellular mobile phone jammer schematic diagram instead of application single taking part in GSM1900 with frequency from 1930 MHz to 1990 MHz. The GSM1900 cellular cell phone meet people is made use of by USA, Canada and.... -
Mobile phone, phone battery chargers on hand wearing the souk are quite expensive. This circuit presented at juncture comes so a low-cost alternative to charge cellular phone telephones/battery packs with a rating of 7. 2 volts. You are reading the Circuits.... -
Today phone has become an integral part of our lives. It is the most widely used communication tool in the world. Owing to its immense popularity & widespread use, there arises a necessity for call recording devices, which find application in call cent-res,.... -
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.... -
If you ever wondered how those phone bugs from spy movies work, here is the schematic for your very own. This simple FM transmitter uses a phone line to both power the device and receive the audio signal. Just hook it up to the phone line you want to monitor.... -
What is a circuit breaker? When do I need an ac power line filter or a phone line filter; How do I design a noise filter; Can I build a homemade surge protection? The following circuit protection can provide several protections you can experiment yourself at.... -
SINCLAIR is a one channel PHONE DIALER, able to send, on the commuted phone line, the alarm messages previously recorded to the NOT volatile DAST memory, to the set numbers, previously saved on the NOT volatile EEPROM memory.. -
Audio from a telephone line can be obtained using a transformer and capacitor to isolate the line from external equipment. A non-polarized capacitor is placed in series with the transformer line connection to prevent DC current from flowing in the.... -
Normally mobile batteries have a lifespan of 2-5 years under normal usage. But then we have to replace them. Nowadays there are cheap replacement batteries which cost no more than 1$. But these low cost batteries run only 6-12 months. What to do with the.... -
At present, it is numerous to adopt the telephone line as long-range control and alarm system of the transmission medium, associated too more research [1, 2 ]. This kind of system is generally made up of alarm device and calling the police to accept the.... -
Telephone ring amplifier of Service Speaker phone ringing bell Circuit diagram Electronic items Resistance of 33 kilo ohms 2 Resistance 47 Kilo Ohm... -
This Phone FM transmitter connects in series to your telephone line and transmits the telephone conversation over the FM band when you pick up the telephone handset. Transmitted signal can be tuned by any FM receiver. The circuit includes an "On Air" LED....
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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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