AmplifierCircuits

TDA8927/TDA8929  general description: The TDA8927 is the switching power stage of a two-chip set for a high efficiency class-D audio power amplifier system. The system is split into two chips: TDA8927J/ST/TH; a digital power stage in a DBS17P, RDBS17P or HSOP24 power package TDA8929T; the analog controller chip in a SO24package. With this chip set a compact 2 × 80 W audio amplifier system can be built, operating with high efficiency and very low dissipation. No heatsink is required, or depending on supply voltage and load, a very small one. The system operates over a wide supply voltage range from ±15 up to ±30 V and consumes a very low quiescentcurrent. TDA8927/TDA8929  features: High efficiency (>94%) Operating voltage from ±15 to ±30 V Very low quiescent current High output power Short-circuit proof across the load, only in combination with controller TDA8929T Diagnostic output Usable as a stereo Single-Ended (SE) amp...

      Modern integrated class D UMZCH combine seemingly incompatible: high efficiency and low THD. This article describes the basic principles of Class-D amplifiers and describes the line chips UMZCH American firm MPS (Monolithic Power Systems). Recently, the power amplifier circuitry (UMZCH) have developed two contradictory directions: Improvement in the subjective quality of sound reproduction, usually by reducing the efficiency (COP) of the amplifier; Increased efficiency of the amplifier and reduce its size while maintaining high quality performance. The first direction is characterized by using the output stages UMZCH powerful field-effect transistors and vacuum tubes (Hi-End), often working in class A. The second direction is characteristic of wearable and automotive audio equipment. It is in realization of this direction are widely used amplifiers class D, and high-quality sound reproduction apparatus stationary class D is most commonly u...

STK465  g eneral description:      A amplifier of acoustic frequencies can be manufactured with discernible materials, despite is known so much the difficulties of finding of materials, what the problem of regulations. These difficulties are overcome relatively easily if we find amplifier in form completed. Completed STK465 is an amplifier of acoustic frequencies that offers qualitative output, using minimal exterior elements. Substantially he is one of big completed force. Has a line pins and incorporated metal surface for adaptation in cooler. The provision pins in a line, facilitates the placement completed in the end printed and his support in cooler. The circuit functions in a big range of benefits of catering, from 20V as 60V, and it attributes 30WRMS, when the tendency of catering is above 50V and composer resistance of loudspeaker is the 4 or 8 Ohm. The catering should be symmetrically.      When it functions with tendency 56V then...

This circuit uses two transistors and one IC (555 timer IC) to produce a pulsating ultrasonic frequency. Transistors Ql and Q2 are connected in a direct-coupled oscillator. The frequency of that oscillator is set by capacitor CI. The oscillator output is taken from the emitter of Q2 to pin 7 of IC1. Transistor Ql is an npn transistor, and Q2 is a pnp transistor. The signal of pin 7 on IC1 causes the output signal appearing on pin 3 to be modulated or varied by the audio frequency developed by Ql and Q2. The IC itself is connected as a stable multivibrator with a frequency that is determined by C3. Capacitor C3 sets the basic frequency to be well above the human hearing range (ultrasonic). The combined modulated ultrasonic frequency appears on pin 3 of IC1, where it is coupled by capacitor C4 to the piezoelectric transducer.

Using two NE555 timer IC devices, this circuit generates either pulsed or continuous ultrasonic signals. The values of CT for both pulse rate and ultrasonic frequencies can be calculated this way. SPKR is a small hi-fi tweeter. NE555 Ultrasonic Sound Source

Guitar Amplifier g eneral description:      This design adopts a well established circuit topology for the power amplifier, using a single-rail supply of about 60V and capacitor-coupling for the speaker(s). The advantages for a guitar amplifier are the very simple circuitry, even for comparatively high power outputs, and a certain built-in degree of loudspeaker protection, due to capacitor C8, preventing the voltage supply to be conveyed into loudspeakers in case of output transistors' failure. The preamp is powered by the same 60V rails as the power amplifier, allowing to implement a two-transistors gain-block capable of delivering about 20V RMS output. This provides a very high input overload capability. Guitar Amplifier  f eatures:  Sensitivity: 35mV input for 40W 8 Ohm output42mV input for 60W 4 Ohm output Frequency response: 50Hz to 20KHz -0.5dB; -1.5dB  40Hz; -3.5dB  30Hz Total harmonic distortion 1KHz and 8 Ohm load: Below 0.1% up to...

Amplifier these recorder can be used in two ways - as a two-channel bridge with a maximum power of 2x25 W or as with a conventional four-load connection and "virtual ground". Power in this case is 4h7Vt. The most famous member of this family - Sony 1253/1853. To work with a subwoofer also need to use a dual-channel configuration. Fig.1. Selecting the connection type, as in the previous case, be subject to the sensitivity of heads. A variant for capacitors C1, C2 act as HPF. They may be waived if the application heads provide undistorted reproduction of lower frequencies. Branch constant component produced internal capacitors radio. However, for option B necessarily the presence of two high-pass and low-pass filter for the stereo for the total channel. Their mission - to eliminate the parallel operation of heads at low frequencies. Since the impedance at low frequencies is almost equal to their heads DC resistance, lack of filters can lead to overload the amplifie...

     In the operation is still a lot of these "dinosaurs" of the mid 90s. A characteristic feature of built-in amplifiers such devices - they are designed for load 2 ohms and have a good supply of power. This is due to the fact that in the middle position fader front and surround speakers are connected in parallel. However, to use them in conjunction with acoustic component is impossible. The reason is simple - the introduction of the fader increases the output impedance of the amplifier, which leads to a change in crossover. Therefore, the only option enhancers such devices with modern acoustics - dual channel configuration, with the fader excluded from work.      In this version, you can add a subwoofer to include it in a "mixed-mono". Since the relationship between the levels regulate front speaker and subwoofer impossible, depending on the sensitivity applied to select one of the heads of connectivity options.      Option ...

Consider the circuit connection to the AC amplifier with two bridge output channels. Dynamic head BA1, BA2 speakers form the left and right stereo channels. They are shown conventionally broadband. Low-frequency head BA3 is connected between the output of the amplifier left and right channels, the signals are summed and head reproduces a mono signal. This connection will be sure to have two high-pass and low-pass filter for the stereo for the total channel. Their mission - to eliminate the parallel operation and overload amplifier heads. Usually used for stereo first order filters (C1, C2), for the total - the second (C3L1) or third.Their payment is made in the usual way. Crossover frequency of the LPF and the order chosen in the range 80 ... 200 Hz, depending on the location of the low-frequency head. If it is placed in the rear compartment, the crossover frequency should be selected as low as possible, and the order - up to avoid reproducing the subwoofer "voice" ...

Introduction Recently could hear a lot of questions about speakers and subwoofers. The vast majority of responses can be found on the first three pages of any book written by professionals. Material is addressed primarily to beginners, lazy ;) and rural Homebrew, prepared on the basis of books I.A.Aldoschinoy, V.K.Ioffe partly Ephrussi, journal publications in Wireless Worrld, AM and (some) personal experience. NOT used information from the Internet and Fidonet. The material is in no way purport to lighting problems, and is an attempt to explain the basics of acoustics on the fingers. Most often, the question goes something like this: "the speaker found that to do with it?" Or "tovarischch and say such subwoofers are>." Here we consider only one solution to this problem: For existing dynamics to make a box, with the optimal settings for HCH as possible. This option differs from the task factory designer-pull system to lower the frequency of the requir...

It is based in protection circuit Audio Analogue Aida - from the site of its designer Federico Paoletti . I developed it a little bit and used in his new mobile amplifier - also borrowing from Paoletti. The scheme is applicable to any PA whose output - compound emitter follower (2 stages or more, or a Darlington Naturally - silicon, or a cascade of CMOS). In the original scheme in the traditional circuit protection (voltage drop across the emitter resistor opens key bypass transition BE composite output transistor) added two optocoupler (circuit shunt base for the upper and lower arm). Current drawn from the shunt base flows through the LED of optocoupler and opens galvanically isolated key. Fine, but the same node can not just arbitrarily turn off power, but doing it on the pitch outside. Need another pair of optocouplers, shunt BE transitions output transistors: Threshold set divider R1-R2 based on the current limit for each transistor and the emitter resistance in the ...

In life, frequent situations where, for whatever reason speakers connected to an audio amplifier, the power of which exceeds the maximum allowed for a system that, on the one hand, often produce the best sound quality, increase the dynamic range, with another - increases the risk of damage due to overload dynamic heads. This is especially true when using the speaker on school, student, youth parties, where the acoustics are often connected to the first that fell known good amplifier that is "powerful." To prevent damage to the speakers when applying for her power, exceeding the nominal, it is necessary to equip the unit overload protection, built-in speakers and requires no additional power supply. Schematic diagram of such a device designed to protect the AC power 10 ... 35 W is shown in below Protection device speakers circuits Also in case of overload tripping SS, this device also protects it from damage by the dynamic head in the event of failure of the ...