WhatsApp Advertisement Keep in touch with your family members from one room to another and also from outside areas such as the garage, using this intercom circuit for bidirectional communication. The circuit is built around two low-power LM audio amplifiers. Block diagram Fig. It has two simple and identical channels—unit 1 and unit 2. As shown in Fig. The circuit also works with carbon microphones or other high-level and low-impedance microphones.

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There are also transistors that have one junction, such as the junction field-effect transistor, or no junctions at all, such as the metal oxide fieldeffect transistor MOSFET. During the design and manufacture of transistors, the characteristics can be predefined and achieved.

The negative N -type material inside an NPN transistor has an excess of electrons, while the positive P -type material has a lack of electrons, both due to a contamination process called doping.

The BC transistor comes in one package. When several are placed in a single package, it is usually referred to as a transistor array. Arrays are commonly used in digital switching. Eight transistors may be placed in one package to make layout much easier. The plates are charged to a total charge. V is the voltage of the biasing battery. A is the Area of each plate. A change in plate spacing will cause a change in charge Q and force a current through resistance R.

This current images the sound pressure, making this a pressure microphone. The speaker with resistance of 8 ohm and power rating equals to 0. An electrolytic capacitor is a capacitor that uses an electrolyte an ionic conducting liquid as one of its plates to achieve a larger capacitance per unit volume than other types, but with performance disadvantages. All capacitors conduct alternating current AC and block direct current DC and can be used, amongst other applications, to couple circuit blocks allowing AC signals to be transferred while blocking DC power, to store energy, and to filter signals according to their frequency.

Most electrolytic capacitors are polarized; hence, they can only be operated with a lower voltage on the terminal marked "" without damaging the capacitor. This generally limits electrolytic capacitors to supplydecoupling and bias-decoupling, since signal coupling usually involves both positive and negative voltages across the capacitor. The large capacitance of electrolytic capacitors makes them particularly suitable for passing or bypassing low-frequency signals and storing large amounts of energy.

They are widely used in power suppliesand for decoupling unwanted AC components from DC power connections. It is constructed of two or more alternating layers of ceramic and a metal layer acting as the electrodes. The composition of the ceramic material defines the electrical behavior and therefore applications.

Ceramic capacitors are divided into two application classes: 9 Class 1 ceramic capacitors offer high stability and low losses for resonant circuit applications. Class 2 ceramic capacitors offer high volumetric efficiency for buffer, by-pass and coupling applications.

They can act as voltage dividers, or as variable resistors. There are tons of resources on the web about pots, so what Im going to cover here are the basic types, operation, and uses specifically for guitar audio.

Pots come in all sorts of shapes and sizes. The most common type we use in pedals and amps are usually of the 24mm or 16mm round metal can type. There are also multigang pots which stack multiple independent pots on one shaft , slider pots, trimmer pots, etc.

In the case of a standard pot, as shown above, we have a round case with three connectors and a shaft that turns. Heres what it looks like in a schematic: Fig. Pin 2 is called the wiper. These numbers map to the schematic symbol like this: Fig.

Potentiometer: as a trimmer resistor. Heres what the schematic looks like: Fig. As you turn the shaft, the resistance decreases.

You are forming a simple resistor whose value is variable. But what happens if the potentiometer fails for some reason age, poor quality, dirty, etc. If the wiper which is the rotating part of the 12 component and probably most prone to failure shorts out, it will let the full amount of signal through. By attaching lug 1 to lug 2, we are building in a fail-safe. This ensures that the circuit is never completely openthere will always be some resistive path in case the wiper goes south.

A Volume Control Now lets look at a more interesting example: a volume control. Assume we have a simple stomp box that does distortion or overdrive or something else interesting. At the end of the circuit we have an output. Wouldnt it be nice to control the output level or volume of the pedal. To see how this works, assume you have the shaft turned all the way clockwise, i. In this configuration, there is little if any resistance across lugs 2 and 3 so the maximum output signal goes to the output.

This causes more of the signal to be dumped to ground. This dumping essentially sends the signal into oblivion, thereby lowering the overall output level. So if you think about it, you are never really turning the volume up! The volume or level in the circuit is always running at full tilt. What you are doing the above volume control is actually attenuating making smaller the full volume that was there to begin with. After that arrangement of component and sufficient material for constructing the PCB and circuit design, decided the circuit design on PCB.

The printed designed circuit paste on the PCB for printing of circuit strip wire and it remove the all remaining metal of PCB except the wire strip metal by chemical of Ferric Chloride. After that Soldering process will started according to circuit diagram.

There are mentioned in broadly process follows as, 3. In which arrangement the component of size of padding and wiring whose will place for better design. These are all section describe in following. Which is shown in below fig. In this fig. Capacitor C4 f and capacitor C5 0. So capacitor f maintains the voltage for next circuit if voltage decreases across the LED. In this process voltage supply continuous in manner as per requirement.

This circuit is known as Low Pass Filter which is shown in below fig. The circuit is a RC low pass filter, it is use for passes low frequency AC signal, but reduces or stop high frequency signals. The reason that these circuit react to the frequency of a signals is because the reactance Xc of a capacitor depends on the frequency f. On the other hand at low frequency Xc is very large, and so the capacitor behaves like an open circuit.

In this low pass filter fig. We can find this frequency by simply solving this equation for the frequency. Here low-Level signal isamplified by the amplifier built around transistor T1 which is shown in below fig. In this circuit consist of one transistor, resistor, and capacitor. Here operation with the collector-emitter feedback bias in which further improve the level of stability, the emitter resistance is connected in the collector bias circuited to provide both collector and emitter feedback.

According to fig. For example, if the emitter ofT1 is connected to ground, the value of R12 could be as low 1 kilo-ohm. Also R1 resistor shows in fig. Because, preamplifier may exhibit instability at very high frequencies. In this circuit analysis applying KVL to the base circuit shown fig. This type of amplifier is an audio amplifier and which amplifier built around gains which are enough to work with the condenser microphones.

The amplified signal fed to the speaker LSP2 by audio amplifier. The communication is properly done without any interference between different circuit section in the design. Design is done to meet all the specifications and requirements. Circuit is implemented by several methods like, designing pcb, soldering ect. It can be concluded that the design implemented in the present work provide portability, flexibility and the data transmission is also done with low power consumption.

As we know that, Intercom is one of the most useful devices in urban area. Which is used for between the house and the shop, between the tree house and the fort, between your kids rooms, etc. It also Keep in touch with your family members from one room to another and also from outside areas such as the garage. Our project provides an efficient method for communication in between two devices. The system is easy to implement and has wide applications in the areas where large amount of usage can be.


Mini Project INTERCOM LM386 by Abid Parwez

Lets me explain to you about the intercom. Read below! Basic Intercom Learning See in the block diagram of a basic intercom. We notice it has a microphone too. When we speak to a MIC1 of intercom 1. It will change your voice to an audio signal to a speaker SP2 of intercom 2. And, this speaker will convert that signal to the voice is the same a sound for MIC1.


Intercom Using LM386


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