hi fi stereo multiplexer for fm

Posted on Feb 6, 2014

A Left and Right source of audio are first pre-emphasized (HPF) and then fed to adder circuits. The output of one adder is the sum of the two signals, or the L + R signal (the monaural signal), and the output of the other adder is the difference of the two signals, or L R. The L R signal is applied to a balanced modulator along with a 38-k

Click here to download the full size of the above Circuit.

Hz signal. The output of the balanced modulator is a DSBSC AM signal centered at 38 kHz. A portion of the 38-kHz signal is divided in frequency to become 19 kHz, and all three signals are applied to a summary/adder circuit at the output of the generator. The L + R signal, which contains baseband frequencies from near 0 Hz to 15 kHz, occupies that portion of the frequency spectrum. The 19-kHz tone is pilot sub-carrier signal, which will be used at the receiver to aid in the demodulation of the received signal. The L R signal, which has been DSBSC amplitude modulated by a 38-kHz tone, occupies the frequency range from 23 to 53 kHz. In FM, the noise increases with modulation frequency. To compensate for this effect, FM communication systems have incorporated a noise-combating system of pre-emphasis and de-emphasis. Pre-emphasis provides increased amplitude to the higher modulating frequencies prior to modulation under a well-defined pre-emphasis (high-pass filter) curve. This added amplitude will serve to make the higher frequencies more immune to noise by increasing their index of modulation. De-emphasis is just the opposite operation (using a low-pass filter) and it is done at the receiver. The NJM2035 is an integrated circuit used to generate a stereo composite signal and obtain switching out and 19Khz pilot signal due two input audio signal and 38Khz X-tal and few external CR. This stereo encoder is the perfect solution...

Visit page

Leave Comment

characters left:

Related Circuits

Color sensor

Color sensor. Colour sensor is an interesting project for hobbyists. The cir- cuit can sense eight colours, i.e. blue, green and red (primary colours); magenta, yellow.

Dew sensor

Dew sensor. Dew (condensed moisture) ad- versely affects the normal per- formance of sensitive electronic devices. A low-cost circuit described here can be used to.

Audio Visual Ringer

Audio Visual Ringer. Many a times one needs an extra telephone ringer in an ad-joining room to know if there is an incoming call. For example, if the telephone is installed in.

Multipurpose Circuit for telephone

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

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

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...

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.

New Circuits

Zero consumption Anti-theft High power Code Switch for E-Bike Batteries

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....
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....
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....
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....
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....
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,....
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....
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....
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.....

Create NOW your QR MENU for your Restaurant / Hotel / Bar / Caffe,

Comprehensive ordering/paying features. fully personalized to suit your Business.

Update Anytime! Easy and Simple!

Popular Circuits

Programable Board with 32K RAM

While there is a list of features that I would like to add (32k EEPROM support, line numbers to...

Digital weight scale

This circuit employs a potentiometer as the weight sensing element. An object placed upon the...

Car lamp charger

The schematic diagram come from circuit: Car Lamp Charger power supply. Go to that page to read...

Function Generator

The design includes a buffered virtual ground circuit provided by an LM741, LM318 or similar Op...

Amplifying DC Diode Detector Output

The very small DC voltages at the output of the diode detector are difficult to amplify...

op amp lm741 pre amp mic schematic

This is the circuit of Op-Amp Microphone Preamplifier using a single power supply, this circuit...

lm 3915 sound level meter circuit

This is a one chip sound level meter that can be use for displaying sound level of an amplifier...

Voltage-to-Frequency And Frequency-to-Voltage Converter

The AD652 Synchronous Voltage-to-Frequency Converter (SVFC) is a powerful building block for...

Anti-theft car audio system circuit diagram

Anti-theft car audio system circuit is shown, which is taken from the car battery 12V DC power...

555 Simple circuit diagram of the timing of time

As shown for the long timing circuitry simple. Press the switch AN start timing, tone PR can...