Audio Amplifier Circuits
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The ground side of the speaker is connected to the junction of two equal high value capacitors (1000 µf is typical) across the supply. The amplifier output voltage will be Vs/2, and so will the voltage across CI (if CI and C2 are equal); so as the supply....
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Sometimes called the JFET µ-amp, this circuit provides a very low power, high gain amplifying function. Since µ of a JFET increases as drain current decreases, the lower drain current is, the more gain you get..
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Instrumentation amplifiers (differential amplifiers) are specifically designed to extract and amplify small differential signals from much larger common mode voltages. To serve as building blocks in instrumentation amplifiers, op amps must have very low....
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Three-amplifier circuit consumes only 135 /tW of power from a ±1 V power supply. With a gain of 101, the instrumentation amplifier is ideal in sensor interface and biomedical preamplifier applications..
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This circuit shows a method which increases the power capability of a drive system for audio speakers. Two HA-2542s are used to operate on half cycles only, which greatly increases their power handling capability. Bridging the speaker, as shown, makes 200 mA....
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The amplifier"s gain is nominally 20 dB. Its frequency response is determined primarily by the value of just a few components-primarily C1 and Rl. The values in the schematic diagram provide a response of ±3.0 dB from about 120 to over 20,000 Hz.....
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Sound detected by electret microphone MIC1 is fed to IC1"s input through resistor R2, and capacitors Cl and C2. Resistors R2 and R5 determine the overall stage gain, while C2 partially determines the amplifier"s frequency response. To ensure proper....
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The LM383 is an audio-power amplifier that is capable of producing up to 8 W of audio output. R1 is essentially a load resistor for the hand-held transceiver"s audio output. R2 can be composed of two fixed resistors in a 10:1 divider arrangement, but using....
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Electronic scales have come into wide use and the HA-510X, as a very low noise device, can improve such designs. This circuit uses a staingauge sensing element as part of a resistive Wienbridge. An auto-zero circuit is also incorporated into this design by....
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The circuit can use any general-purpose, low-offset, low-drift op amp, such as the OP-07. The differential signal from the bridge feeds an amplifier that drives an ordinary, rugged ±50-p.A meter. Near the null point, however, the drastically reduced....
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This circuit shows amplifier Al as a sensor amplifier in a bridge configuration. Amplifiers A2 and A3 are configured as a voltage to frequency converter and A4 is used as the transmitter. This entire sensor/ transmitter can be powered directly from a 4 to....
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In applications involving strain gauges, accelerometers, and thermal sensors, a bridge transducer is often used. Frequently, the sensor elements are high resistance units requiring equally high bridge resistance for good sensitivity. This type of circuit....
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The LT1007 is capable of providing excitation current directly to bias the 350-0 bridge at 5 V. With only 5 V across the bridge, as opposed to the usuallO V, total power dissipation and bridge warm-up drift is reduced. ..
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This audio amplifier design approach employs TMOS Power FETs operating in a complementary common- source configuration. They are biased to cutoff, then turn on very quickly when a signal is applied. The advantage of this approach is that the output stage is....
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Ul, an FET op amp needs a bipolar voltage atpins 4 and 7 with a common ground for optimum gain. You can calculate the gain by dividing R2 by Rl. Zero-set balance can be had through pins i and 5 through R3. Put a voltmeter between pin 6 and ground and....
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In this circuit, a 2-MHz clock is divided by eight in Ul, providing a stable 250-kHz carrier. Ql and Q2 buffer the clock and provide a low-impedance drive for op amp U4, which is a high-gain amplifier and integrator. U4 accepts audio inputs and converts the....
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The single speaker amplifier circuit uses current feedback, rather than the more popular voltage feedback. The feedback loop is from the junction of the speaker terminal and a 0.5-0 resistor, to the inverting input of the NE5534. When the input to the....
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The input is ac coupled to the amplifier through C2, which blocks de signals that might also be present at the input. The Rl/Cl combination forms a low-pass filter, which eliminates unwanted high-frequency signals by bypassing them to ground when they....
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This amplifier delivers 20 W into an 8-D load using a single IRF520 driving a transformer coupled output stage. This circuit is similar to the audio output stage used in many inexpensive radios and phonographs. ..
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The CA3080 can be used as a gain controlling device. The input signal is attenuated by R1/R2 so that a 20-mVpp..
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Designers can build a 15-dB compressor with a miniature lamp and a current-feedback amplifier. The circ..
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This simple receiver AF amplifier can supply several hundred milliwatts to an 8- speaker. The gain is about 200X. If..
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An electric guitar often has to be connected to a mixing panel, a tape deck or a portable studio. As far..
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A line amplifier is always a useful unit to have around, whether it is for matching a line signal or raising..
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When an inverter is biased with one resistor from its input to output in the range of 100 KOhmhm to 10 and is capacitor c..
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Frequently, the output current of an operational amplifier is inadequate for the application as, for instance, when a s..
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Figure 39-2"s circuit combines a low-noise op amp, IC1, with a chopper-based carrier-modulation scheme to ..
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The 20-W + 20-W stereo amp consists of two complete, separate 20-W RMS bridge-type amplifiers. The input signal source is brought into the amplifier through the voltage divider network, which is made up of Rl, R2, and PI. Resistor Rl provides a load....
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Designed to feed a low-frequency subwoofer speaker system, the amplifier is capable of up to 100 W into an 8- load. The OPA541BM op amp requires heatsinking and is manufactured by Burr-Brown Corporation. ..
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The circuit, built around an LM741 op amp configured as an inverting amplifier, is used to drive complementary transistors (Ql and Q2). The op amp`s feedback loop includes the base-emitter junctions of both transistorsan arrangement that helps to reduce....
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An Apex PB50 Booster Amplifier, plus an IC op amp, can be used in a high-voltage op amp that converts a small analog signal to a 180-V p-p signal.Apex Microtechnology manufactures a number of power op amps...
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This line driver can drive low-impedance lines with up to 70 V p-p max. IC1 is a low-noise op amp suitable for 15-V operation. T1 and T2 are regulators for the power supply for IC1. T3 and T4 form a complementary power output stage...