HI-FI Stereo Multiplexer for FM transmitter with NJM2035 I.C. circuit

Stereo Multiplexer for FM transmitter
 

FM stereo broadcasting was introduced during the early 1960s. The scheme that was adopted was chosen to be compatible with the monaural FM radios that were in existence at the time. Essentially, the system performs the multiplexing of two signals and further combines them into a complex baseband signal that modulates the FM carrier. Figure 1 shows a block diagram of the typical analog-stereo generator used to drive an FM transmitter.
FM Stereo Multiplexing

Figure 1: FM Stereo Multiplexing



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
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10 Band Graphic Equalizer circuit with KA2223 and PCB

10 Band Graphic Equalizer circuit
10 Band Graphic Equalizer circuit
Description
Graphic equalizers are a must in any good hi-fi systems! They enable you to shape the response of the system to the particular room, or in recordings to improve deficiencies of the equipment or the original recording.

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30 Watt power amplifier with Russian valves 6N1 - 6P3P

30 Watt power amplifier with Russian valves 6N1 - 6P3P

For most of us, a high power tube amplifier is unaffordable. This kit changes that, so that now everybody can enjoy that powerful and lush "tube sound". The sound of tubes has never been surpassed, neither by transistors nor by FETs.
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TC9153 Low cost stereo digital volume control

TC9153 stereo digital volume control circuit

TC9153 stereo digital volume control circuit

The TC9153 is a CMOS designed for electronization of dual volumes.

It is suitable for M/C, car or Hi - Fi stereo.
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Tone control subwoofer low pass filter

Tone control subwoofer low pass filter circuit
PT2350 is a tone control subwoofer cross-over low pass filter chip utilizing CMOS Technology. It features a tone control range of + 10dB (50Hz, 4 KHz) and subwoofer low pass filter of the second order Sallen Key Design.
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100 LED’s Solid State Oscilloscope

100 LED’s Solid State Oscilloscope

Solid State Oscilloscope

It uses a matrix of 100 LED’s for a display, and does suffer from being slow and having rather poor resolution. Still we could display a sine wave running at 500Hz without trouble, that that's not all that dissimilar to commercial solid state oscilloscopes.
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Class AB BJT 100 Watt Hi-End audio power amplifier circuit

Sym5 Class AB BJT 100 Watt Hi-End audio power amplifier circuit topSymasym5
Symasym5, is a "cute" power amplifier, designed with quality but still low price in mind. This resulted in a ClassAB BJT amplifier, using only TO92 transistors for input and VAS, with a reasonable part count. The topology used is well known and consist of a single diffamp for input, plus a 2nd diffamp with current mirror for VAS.
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Actrk 400 / 600 Watt power amplifier with IRFP460 Mosfet

Actrk 400/600 Watt


Two versions of a robust module capable of delivering high powwer for extended periods.  The Actrk400 uses 6 n-channel Mosfets in the output stage to deliver around 400 watts into 4 ohms while the Actrk600 uses 12 n-channel Mosfets in the output stage to deliver power in excess of 600 watts into 4 ohms.  One constructor has achieved almost 900 watts with the Actrk600 layout using 12 IRFP460 Mosfets.


Actrk 600W schematic


Actrk 600W schematic
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2 x 15 watt stereo audio power amplifier circuits based TDA1521

It is small and compact stereo amplifier is powerful but can easily be used to replace your broken amplifier or new construction, or to make an active speaker, in all cases combined with a preamplifier. With remarkable features make it the true Hi-Fi amplifier.
Using only active component (the right and left channel) Philips TDA1521 monolithic integrated circuit, which contains a double line-end audio amplifier completely independent, each capable of providing from 10 to 12 W to the load 8 ohm or 15 W into 4 ohms (30 W music). Voltage gains of the amplifier is fixed at 30 dB.
2x15w stereo power amplifier circuits with TDA1521
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16×1 LCD Display for Clock / Calendar Circuit Board Design using PIC16F628



Clock/Calendar Circuit
Clock/Calendar Circuit 

This Clock/Calendar Circuit BoardDesign uses a 16×1 LCD Display with 4-bits interface. This circuit design is capable to display many characters. Time and date are displayed as HH:MM:SSx mmm dd, where: HH = Hours MM = Minutes SS = Seconds x = AM/PM mmm = Month (Jan, Feb, Mar) dd = Day.
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300 Watt audio power amplifier (Elektor 11 / 1995 PA300 audio power amplifier)

Design by A. Riedl
Taken by themselves, the properties of the PA300 amplifier are not revolutionary. But taken in combination, they show something special: a robust 300 watt hi-fi power amplifier that is not too difficult to build.

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TDA8560Q 2 × 40 Watt 2 Ωhm stereo BTL power amplifier circuits


TDA8560Q 2× 40 W / 2 Ω stereo BTL power amplifier circuit
power amplifier circuits

The TDA8560Q is an integrated class-B output amplifier in a 13-lead single-in-line (SIL) power package.
The device is primarily developed for car radio applications.
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