Stereo Circuits

A stereo power amp designed for use in portable players and radios. A 3V supply can be used to drive headphones providing 20mW in 32 Ohms per channel, and a 9V supply will provide 1W in 8 Ohm per channel for small loudspeakers.

The schematic shown, does no need any power supply because is a simple low frequency passive filter. It could be usefull if you want to drive an extra subwoofer from your stereo system.

TheCA3189E is a comprehensive FM-IF system designed for high fidelity FM tuners. It includes a three stage FM-IF amplifier/limiter configuration with level detectors for each stage, a double-balanced quadrature FM detector and an audio amplifier that features the optional use of a muting circuit. The advanced circuit design includes desirable special features such as delayed AGC for the RF tuner, an AFC drive circuit, and an output signal to drive a tuning meter and/or provide stereo switching logic. In addition, internal power supply regulators maintain a nearly constant current drain over the voltage supply range of +8V to +16V. Distortion is primary a function of the phase linearity characteristics of the external detector coil.

This circuit uses a stereo amplifier IC in a 14-pin DIL package that requires very few external components to make a complete 2 Watt per channel power amplifier. The LM1877N-9 is suitable for use with 8ohm or 16ohm speakers.

This circuit is mainly intended to provide common home stereo amplifiers with a microphone input. The battery supply is a good compromise: in this manner the input circuit is free from mains low frequency hum pick-up and connection to the amplifier is more simple, due to the absence of mains cable and power supply. The circuit is based on a low noise, high gain two stage PNP and NPN transistor amplifier, using DC negative feedback through R6 to stabilize the working conditions quite precisely.

The circuit needs to bring the signal from an electret microphone up to a level suitable for a line input. Based on measurement of the microphone output under a range of conditions, I have chosen two gain levels - 2 & 23. 23 is suitable for everyday general recording. 2 is suitable for live music such as a rock concert. There is a output pot to allow fine-tuning of the level if necessary, but it is intended that usually the wiper will be on the land.

An application, which is considered, of very good quality sound since the entrance transistors are working at Class A. The quality of sound depends to a large extent on IC1, which must be of good quality. It can be chosen from several IC with the best from the point of cost efficiency the proposed NE 5534 (NE 5532 for stereo construction) and the series TL071 (TL072) for greater input impedance. This particular application can be used with very good results and as driver headphone with higher 47R impedance. The amplification can be changed and adapted to the amount we want, if changing the feedback resistors R6/R7.

This circuit uses a single chip, IC BA3812L for realizing a 5 band graphic equalizer for use in hi-fi audio systems.The BA3812L is a five-point graphic equalizer that has all the required functions integrated onto one IC. The IC is comprised of the five tone control circuits and input and output buffer amplifiers. The BA3812L features low distortion, low noise, and wide dynamic range, and is an ideal choice for Hi-Fi stereo applica-tions. It also has a wide operating voltage range (3.5V to 16V), which means that it can be adapted for use with most types of stereo equipment.

A lot of friends me asked to draw a more shrunk circuit 2-ch mixer, which will contain also, operation CROSSFADER. The circuits can be modified and added also other channels, repeating basic that I give. It can are added channels stereo PHONO/line or even channels microphone with proportional modification of next stages. In the Fig.1 exist the input circuits of two channels and input of microphone channel. The two basic channels she is same between them. Thus that its go for a channel, the he is also go for the other. In each stereo channel exist two inputs, classic stereo input PHONO that is practical a correction filter RIAA and concerns the signal amplification of sound that emanates from the classic reproduction heads of classic disks LP.

This is a handy, easy to build general purpose 50 watt amp. The amp has an input for a radio, TV, stereo or other line level device. It also has a phono input for a record player, guitar, microphone or other un-amplified source. With the addition of a low pass filter at the input, it makes a great amp for a small subwoofer.

This project (unlike most of the others, but in a similar vein to Project 19) is based almost directly on the typical application circuit in the National Semiconductor specification sheet. You can also use the TDA3050 (from SGS-Thompson), which has almost identical performance and (remarkably) the same pinouts!

The first application has to be a stereo power amp, since that's what I built using two prototype modules. The reasons for this choice are twofold ... a good high powered stereo amp is always useful, and it was important to be able to assess the sound quality in this role. I am at something of a disadvantage in this, because the only full range speakers I have are bookshelf units. They are quite good, but obviously don't have deep bass capability and suffer the normal limitations of most bookshelf designs.

So all we need is a low power stereo amplifier capable of driving a pair of headphones, and some method of allowing this to be connected to the 9 pin socket on the MegaDrive, along with the RF modulator. Since cable mounting mini-DIN sockets are not readily available, I decided to have a flying lead from the amplifier, fitted with a 9 pin plug to connect to the mega-drive. A 9 pin socket is then fitted to the back of the amplifier, for the modulator.

The circuit is simple, yet is capable of excellent performance. I designed it specifically for use as an amplifier for the digital sound card in my computer. Audio input can be from any two-channel line level device such as a television, CD player, or VCR. It is of the tube type, using only 5 tubes total with no more than about 45 Watts power consumption from the outlet. It uses 3 types of tube 1 5Y3 GT vacuum rectifier, 2 6SF5 GT high-mu triodes, and 2 6K6 power beam amplifiers. These are all full-size octal type tubes which are commonly available today for between $3-5 each.

While doing research for the article Designing an Opamp Headphone Amplifier, I built a portable headphone amplifier for testing purposes. Each channel uses a single Burr-Brown OPA134 opamp in a non-inverting configuration. It has adequate current capability to drive most headphones without an output stage. I have used it with Sennheiser 465s (94dB SPL) and achieved ear-splitting volume. The amplifier is ideal as a booster for power-conserving stereo sources such as portable CD players and for interfacing with passive EQ networks such as tone controls or a headphone acoustic simulator.

This circuit is mainly intended to provide common home stereo amplifiers with a microphone input. The battery supply is a good compromise: in this manner the input circuit is free from mains low frequency hum pick-up and connection to the amplifier is more simple, due to the absence of mains cable and power supply. Using a stereo microphone the circuit must be doubled. In this case, two separate level controls are better than a dual-ganged stereo potentiometer.

This preamplifier was designed to cope with CD players, tuners, tape recorders etc., providing a gain of 4, in order to drive less sensitive power amplifiers. As modern Hi-Fi home equipment is frequently fitted with small loudspeaker cabinets, the bass frequency range is rather sacrificed. This circuit features also a bass-boost, in order to overcome this problem. You can use a variable resistor to set the bass-boost from 0 to a maximum of +16dB @ 30Hz. If a fixed, maximum boost value is needed, the variable resistor can be omitted and substituted by a switch.

This preamplifier was designed to cope with CD players, tuners, tape recorders etc., providing a gain of 4, in order to drive less sensitive power amplifiers. As modern Hi-Fi home equipment is frequently fitted with small loudspeaker cabinets, the bass frequency range is rather sacrificed. This circuit features also a bass-boost, in order to overcome this problem. You can use a variable resistor to set the bass-boost from 0 to a maximum of +16dB @ 30Hz.

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 that is minimised the noise. The circuit does not require big current in order to it work.

I started this project after reading an article in Stereophile magazine called "Aunt Corey's Buffered Passive Preamplifier" by Cory Greenberg (Stereophile, November 1991, pg. 91). My version can be both a great headphone driver and preamp. The 4 ohm output of the buffers will drive headphones without reaching their maximum output current. The idea with buffers is that with unity gain you should be minimizing any distortion added to your signal. And trust me, the idea works.