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Video Wall circuits
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8051 / 8052
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Off line Telephone tester
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
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
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 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
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.
Cell Phone Battery Meter 3.6 Volt
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 where the TL431 connects to the 1K resistor. The lower reference for the LED at pin 14...
Switching Supply In Telephone Ring Generator
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 voltage, 1 amp transistor) and a driver transistor (2N3053). The inductor should have a low D
Phone Battery Charger circuit Schematic Diagram
USB to phone battery charger circuit Schematic Diagram
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 average-voltage phone battery 3. 5 - 3. 7 volts. That`s why this USB to phone battery charger circuit
Car Mobile Phone Charger Circuit Schematic Diagram
DIY mobile phone jammer Schematic Diagram
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 on the whole of the nations in South America. This cellular phone jammer isn`t applicable on
Low Cost Phone Battery Charger Schematic Diagram
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 of Low Cost Phone Battery Charger And this circuit permalink url it is
Telephone Call Recorder
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, stock broking firms, police, offices, homes, etc. Here they are describing a call recorder
Simple Cell Phone JammerCircuit 2
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 jammier is not applicable for use in Europe, Middle East, nor Asia. The GSM jammier circuit co
2-Line Intercom-Cum-Telephone Line Changeover Circuit
Telephone FM transmiter
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 and tune your FM radio receiver to the transmitting frequency. If you still have a.
Telephone Audio Interface Schematic
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 transformer winding which may prevent the line from returning to the on-hook state. The capacitor sho
Reuse Old Mobile Phone Battery for LED lighting
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 used batteries, which can`t be reused in mobiles Well, easy solution is to use the batteries i
Design of a kind of simple and practical telephone alarm system
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 receiving arrangement, computer of the centre etc. in the user. The alarm equipment finishes ju
Telephone ring amplifier
Telephone ring amplifier of Service Speaker phone ringing bell Circuit diagram Electronic items Resistance of 33 kilo ohms 2 Resistance 47 Kilo Ohm.
Phone FM Transmitter
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 indicator and also provides a switch which can be used to turn off the transmitter. A unique f
Phone Spy Transmitter
Here is a very simple telephone broadcaster transmitter which can be used to eavesdrop on a telephone conversation. The circuit can also be used as a wireless telephone amplifier. One important feature of this phone transmitter is that the circuit derives its power directly from the active telephone lines, and thus avoids use of any external...
Two way Simple Very Small Telephone Exchange
This is a very small telephone exchange attached only two ordinary Tele phones. Fully bi-directional facility with an intercom system. When a phone is in off hook condition, Exchange will detect it & send ringing pulse to other phone. When it will be picked up, the connection will be established between both phones. This will be taken place vice
op amp ringer circuit old telephone
In the process of adapting an old phone to be used as an Bluetooth phone. I am currently testing the ringer circuit, which I build using the schematics provided by Sparkfun. Now, when I hook up just the right part of the schematic to a 3. 5V source (Vcc), I get a nice 45V on the output (with a steady current draw of about 130mA). But as soon
voltage What kind of Mic do I need to connect to a pots telephone line to speak
What kind of microphone or mouthpiece I can use to connect across a pots telephone line in order to send dtmf tones ( no voice ) dtmf only. Can I use a regular mic or does it have to be a certain type, I am using a 300 ohm resistor to hold open the line automatic and I need to know what kind of mic i need or if i will need any
Telephone Line Indicator Circuit
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 permanently connected to the line, since it only draws a tiny amount of current. The schematic sh
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
IP phone to analog phone or modem audio interface circuit
The transformer is a 600:600 ohms transformer (also named 1:1 ratio 600 ohm transformer) : more or less the same number of turns on both primary and secondary coils, and optimized to work at 600 ohms load. Selectronic sells one here. I measured the primary and secondary coils on the one from Selectronic: about 75 mH inductance and 50 ohms
Phone Tap circuit
In this file is a schematic for a simple wiretap & instructions for hooking up a small tape recorder control relay to the phone line. First, I will discuss taps a little. There are many different types of taps. There are transmitters, wired taps, and induction taps to name a few. Wired and wireless transmitters mus
1 Circuit and Wiring Diagram * 2 Parallel Phone TapCircuit * 3 Mobile/Cell
Alarm Phone Dialer
Just hook this Alarm Phone Dialer up to something you would like to monitor, for example, a high water alarm, low temperature alarm, back window, garage door, etc. When the system is activated it will call a number of programmed numbers to let you know the alarm has been activated. This would be great to get alerts of alarm conditions from your ho
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