On most FM tuners, the stereo indicator lights upon detection of the 19-kHz pilot tone. However, this doesn"t mean that the program is actually stereophonic, since the pilot tone is often transmitted with mono programs also. A similar situation exists on stereo amplifiers, where the stereo LED is simply controlled from the mono/stereo switch. The LED-based stereo indicator described here lights only when a true stereo signal is fed to the inputs. ..
This circuit will synthesize two rear channels for quadraphonic sound when fed with a stereo signal. The rear output for the left channel, is a combination of the left channel input 180 out of phase, added to a proportion of the right hand channel (also out of phase)..
The National Physics Laboratory broadcasts a time signal, previously known as the Rugby clock but now called "Time from NPL." Its most commonly known as the MSF signal due to it originally being identified in Morse code those letters. It is broadcast from Anthorn on 60kHz. Many commercial clocks use it to automatically set themselves. I decided to convert a digital clock I bought into one set by the MSF signal. To make the project more interesting I decided to use the.....
The electronic diagram of the monophonic FM receiver made with TDA7088T is shown on Pic.4.12. If built with SMD components it can be placed in a matchbox, altogether with two button-type batteries. The operating principle of this device is given in the previous chapter. The only thing new is a very simple audio amplifier made with BC547 transistor, which is loaded by cheap 16-Ohm headphones. The telescopic antenna is used, as on Pic.4.8...
This is a four channel amplifier ideally suited for use with quadraphonic equipment such as a Sound Blaster Live card. There is no volume control,audio levels being directly controlled from the sound card itself. Construction is straight forward and is suitable for Verobaord. Overall gain is controlled by the ratio R14/R13 and R6/R5. Used with small hifi speakers the volume was too loud for my room so I reduced R14 and R6 to 33k. The zobel network formed by.....
Many times we needed to use a simple circuit of preamplifier, with few components and facility of made. This circuit use a opamp. the Motorola, TCA5550, that contains a double amplifier, as outputs for the adjust of volume, balance, treble and bass. These adjustment of all parameters become from a line monophonic linear potesometers, increasing by far the facility of manufacture. The placement these potesometers should become as much as possible, more near in IC1, so.....
Several people have requested that I set up a web page with construction details for the second of two power amplifiers that I published in Audio magazine. This amplifier is the monophonic 270 watt Double barreled Amplifier. For the original article, I specified plus and minus 85 V dc power supply voltages. The voltage can be increased to about 93 V to obtain a power rating of 300 W...
This is a four channel amplifier ideally suited for use with quadraphonic equipment such as a Sound Blaster Live card. There is no volume control,audio levels being directly controlled from the sound card itself...
This power-stingy combination of an audio codec and touchscreen-interface controller now comprises a differential or two-channel microphone input with automatic level control, a two-channel audio-line input, a separate monophonic-audio input, a PC-"beep" input, and an audio DAC that connects to the AC`97 Version 2.2 system interface...
An LMX1601 Phase locked loop, a discreet FET VCO, and an AVR micro controller combine to make a stable, easy to use monophonic FM transmitter that includes a an audio activated switch that turns the transmitter on only when its being used. The common characteristic of all of the previous low power FM transmitters I've built over the decades, is that their operating frequency is determined by an LC resonant circuit. Some of them had excellent stability, some of them.....
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