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A large number of intercom stations can be tied together. All units are connected in parallel, and the entire system is buzzed by only one signaling circuit. Each unit is powered individually from 1.5-V cells for redundancy. For greater signal volume, 3-V sources can be used for the supplies without changing any other parts of the system. The...
The circuit provides a minimum component intercom. With switch SI in the talk position, the speaker of the master station acts as the microphone with the aid of step-up transformer Tl. A turns ratio of 25 and a device gain of 50 allows a maximum loop gain of 1250. Rv provides a common mode volume control
When activated, the transmitter sends out a 49.890-MHz, AM rf carrier. The.receiver detects, amplifies, and decodes the rf signal, which, in turn, activates a piezo buzzer. The receiver is small enough to carry in a pocket or sit on your workbench.
Amplifier A increases the microphone"s output to a usable level. The output signal is fed to op amp B, which inverts the signal180Â°. A balance-control potentiometer connects across the outputs of amplifiers A and B. 1f an audio tone is fed into the microphone and the balance potentiometer"s wiper is all the way over to the A output position,...
The design consists of an amplifier, a double-pole changeover switch and two loudspeakers: one for the master station and
One-Way Voice-Activated Intercom Circuit
An omnidirectional electret microphone can be used to pick up the sound and convert it into an electrical signal. The output of the microphone is fed along two paths. In the first path, the signal is sent to the inverting input at pin 6. In the second path, the microphone signal is fed to the non-inverting input of U2,
The circuit consists of separate amplifiersâ€”one for each stationâ€”rather than a single amplifier and a time sharing arrangement. Ul and U2 are low-voltage audio amplifiers, each of which operates as separate entities with switches at either station controlling which will transmit or receive. With capacitors C7 and C8 included in the circuit,...
Carrier current remote control device or intercom circuit diagram
Carrier current remote control device or intercom circuit diagram as follows:
Bi-directional intercom system
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...
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 volts and is easily assembled. You can have your own home intercom between the kitchen, the garage, the rumpus room and at your poolside ?barby? and all for less than $100! The ?Link?...
Doorphone Intercom schematic
In this doorphone circuit,an 8 ohm speaker is used both as a microphone and also an output device. The BC109C stage amplifies in common base mode, giving good voltage gain , whilst providing a low impedance input to match the speaker. Self DC bias is used allowing for variations in transistor current gain.
The circuit comprises a 3-stage resistor-capacitor coupled amplifier. When ring button S2 is pressed, the amplifier circuit formed around transistors T1 and T2 gets converted into an asymmetrical astable multivib-rator generating ring signals. These ring signals are amplified by transistor T3 to drive the speaker of earpiece.
No description available.
The Link telephone intercom is designed around two ICs. The first, IC1, is an NE 556 dual timer chip, which is wired up to provide dial tone, ring tone (busy tone too, which will be explained along with a few add-ons to be mentioned later on) and ring pulses for the ringer circuit attached to each line circuit. The other chip, IC 2, is a CD...
old phones as an intercom with ring tone
You may wish to use a 12 to 24V battery, like a Gel Cell, since the car power or cheap power wall wart style supply is probably too noisy. You may have to adjust the resistor value (1.2K for 24V). Whatever gets the phones working and does not use more than 30mA total loop current.
Two line intercom
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 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...
Advanced Telephone Intercom
In order to achieve a status between two levels of switching for two calls at the same time, you must first establish privacy on each call. Otherwise, you will end up with all four phones talking to each other, and that just won't do. So the Link 'P' is an intermediate stage between the basic Link design, and the fully blown one (yet to be...
Baby watch Intercom Circuit
It's a very simple circuit, for the follow-up of baby. It can however be also used for other use, as intercom etc. In the place of M1 we can we use a simple electret mic capsule. The regulation of gain becomes from the R1, whoever can be trimmer or potesometer. Has been added also a small automatism, round the RL1 and battery 9V for the case...
Simple Intercom circuit
The circuit comprises a 3-stage resistor-capacitor coupled amplifier. When ring button S2 is pressed, the amplifier circuit formed around transistors T1 and T2 gets converted into an asymmetrical astable multivib-rator generating ring signals. These ring signals are amplified by transistor T3 to drive the speaker of earpiece. Current...
The Link Telephone Intercom Every Home Should Have One!
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 volts and is easily assembled. You can have your own home intercom between the kitchen, the garage, the rumpus room and at your poolside barby` and all for less than $100! The Link intercom
Video Switch for Intercom System
Nowadays a lot of intercom units are equipped with video cameras so that you can see as well as hear who is at the door. Unfortunately, the camera lens is perfectly placed to serve as a sort of support point for people during the conversation, with the result that there`s hardly anything left see in the video imagery. One way to solve this problem
Low-Cost and Simple Intercom
This is a low-cost and simple intercom circuit design which utilizes 3 transistors. Even a newbie can assemble it on a piece of veroboard without difficulty
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.
This intercom uses an ordinary speaker to function as its microphone. Once the button is pressed, the relay toggles, and the speakers interchange their functions. One works as a normal speaker and the other one works as microphone.
2-Line Intercom-Cum-Telephone Line Changeover Circuit
Intercom Circuit Using LM390
This is a circuit for an intercom is a is a stand-alone electronic communications system intended for limited or private dialogue. Below schematic shows the application circuit of LM390 on intercom. Gain control can be done by capacitively coupling a resistor (or FET) from pin 6 to ground. This is the figure of the circuit;
audio How to create a multi-extension intercom system using wired phones
Create a simple (telephone based) intercom system in our new house. Shouting between rooms is not so good, and trying to use an IM client or Facetime doesn`t have the immediacy of a good shout down the corridor. I`ve got a box of old wired telephones that don`t have much use any more, and will be wiring the new place with cat5e for networking so...
Simple Intercom Circuit
This is simple intercom circuit. Here I have used common Ic LM380. Now the switch is in the talk position for the speaker on the left, And the other persons position is listening position. If other one wants to speak The switch must be change to another position. (Both users should do that). Pins 3, 4, 5, 10, 11, 12 are grounded.
Intercom Circuit for Factories
This is a simple form circuit for a 2-station intercom using common 8R mini speakers. The press-to-talk switches should have a spring-return so the intercom can never be left ON. This is the figure of the circuit; Power the speaker from a separate power supply is the secret to preventing instability (motor-boating) with a high gain circuit like
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
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