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Crossed from: Inside Circuits | Clicks: 19203 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 7
Hi-Fi stereo Preamplifier with tone controls
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The circuit is based on the known chip TDA1524, which is an integrated control Volume, Bass, treble, and Balance. These arrangements are made through 4 potentiometers (P5-P8) with trend. The integrated circuit IC1, to run the needed very few external components. The potentiometer PI-P4 are used to compensate any tolerances POSTS components that regulate the input signal. The input circuit is 5 points and 8 & 10 & 10. The output of the circuit is 7 points and 6 & 10 & 10. To supply to point 9 is a positive trend and 10 negative. Sections 1, 2, 3, 4, 11 and 15 are used for optional remote control circuit.
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Crossed from: Inside Circuits | Clicks: 10943 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
Stereo Preamplifier with balance and loudness
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The circuit of preamplifier use the 5533 chip and features a combination of controls balance and volume. Due to the nonlinearity of the human auditory system, low frequencies must be boosted at low listening levels. Level pay, and LOUDNESS controls provide all the plays to produce the desired response from the music.
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Crossed from: Inside Circuits | Clicks: 12369 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
Fully adjustable preamplifier
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This circuit is a audio preamplifier tha has balance, tone and loudness controls. It should be suitable as an example of good design for audio application. Uses the BAA730 and NE540 chips.
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Crossed from: Inside Circuits | Clicks: 9063 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
Microphone preamplifier with TLC251
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A microphone preamplifier using: om CMOS op amp with its own battery, is small enough to be placed in a case of small microphone. The amplifier operates from a 1.5V battery cathode mercury low supply currents. This preamp will operate at very low power and maintain a reasonable frequency response as well. The TLC251 is operating in low bias (operating at 1.5 V) draws a supply current of only 10 and has a year - frequency response of 3 dB 27 Hz to 4.8 kHz. With 8-pin grounded, which is designated as the polarization state high limit increases above 25 kHz. Supply current is only - 30 pA under these conditions.
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Crossed from: Inside Circuits | Clicks: 8169 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
RIAA preamplifier CA3410
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This circuit has read the RIAA equalization, tone controls, and adequate gain to drive most power amplifiers conunercial by using CA3410 op amp BiMOS. Total harmonic distortion, pushed to provide an output of 6-V, is less than 0.035% in audio-frequency range from 150 Hz to 40 kHz. Full stereo preamp is to duplicate this circuit using the CA3410 remaining two amplifiers.
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Crossed from: Inside Circuits | Clicks: 18218 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
Stereo Preamplifier Circuit (741)
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The circuit works with two 741 opamps and provides better than 20 dB gain in each channel. A better type op-amp will give a better noise figure and bandwidth. In this circuit, the sharp roll-off is at 20,000 Hertz.
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Crossed from: Inside Circuits | Clicks: 10589 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
4 microphones mixer circuit with TL081
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A TL081 op amp is used as a high impedance to low. converter and a signal mixer. The input impedance is about 1 megohm and the output impedance is about 1 kohm. Two 9 volt batteries are used as power source.
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Crossed from: Inside Circuits | Clicks: 14786 | Votes: 1 | Comments: 0 | Rating: 5 | Rank: 3
Automatic level control with NE570
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The NE570 can be used to make a high performance compressor FTA, except that the rectifier is connected to the input. This makes gain inversely proportional to the input level so that a drop of 20 dB input level will produce an increase of 20 dB gain. The output remains at a constant level. As shown, the circuit will maintain an output level of ± 1 dB for an input range of + 14 to -43 dB at 1 kHz.
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Crossed from: Inside Circuits | Clicks: 4597 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
Auto gain control op-amp circuit
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An audio signal applied to VI is passed through the operational amplifier 741, U2. After being amplified, the output signal V2 is sampled and applied to a negative voltage doubler / rectifier circuit composed of diodes CRI and CR2, with the capacitor C1. The resulting negative voltage is used as a control voltage which is applied to the door] 2N5485 FET Q1. Capacitor C2 and resistor R2 form a filter for smoothing the voltage rectified audio control. The lFET is connected between pin 2 of the MC3340P grounded by a resistor of 1 kohm....
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Crossed from: Inside Circuits | Clicks: 10289 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
Low distortion audio gain limiter
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The level at which the limiter kicks in audio can be adjusted with the selector knob LIMIT LEVEL. When this level is exceeded, the output of the half-LIMITING detector of the op-amp (used as a comparator) turns the LED causes the resistance of the photoresistor to decline rapidly. It is in tum causes the gain of Ie half LIMITED op-amp to decrease.
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Crossed from: Inside Circuits | Clicks: 16554 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
Small leakage pre-amplifier
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The circuit uses the LM301 has an input leakage of only 2 pA typical at 75 ° C and is used with 1 M ohm input resistance. The operating voltage has to be +-12V.
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Crossed from: Inside Circuits | Clicks: 9888 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 5
Low Noise Moving Coil Audio Preamplifier
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This preamplifier was designed for low resistance sources like moving coil heads (MC). The circuit uses in parallel three duble transistors SSM2220 or MAT03 and by forming a diferential amplifier keeps noice low. Connecting this amplifier in front of a OP27 amp we gain even lower noise. Also the reason we use PNP rather NPN transistors is because they have les low frequency noice. ..
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| Clicks: 19629 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
Selectable sensitivity Preamplifier
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Most audio amplifier systems must have preamplifiers with many different characteristics. These include high-gain linear response for magnetic microphones, low-gain linear response for tuners, and high-gain RIAA equalization for magnetic phone cartridges. To meet this broad requirement, most amplifier designers include a single universal preamplifier circuit. Basically a high-gain linear amplifier, its characteristics can be altered by switching alternative resistor filter networks into its feedback system...
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| Clicks: 14019 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
HiFi stereo preamplifier with tone control
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The preamp featured is very straightforward to make on the PCB, and has an innovative tone defeat function. Rather than completely disable the tone controls, they are massively de-sensitised, and when "defeated" have a maximum range as shown in Fig. 3 (below). This can be increased if desired, so you can have two tone control settings, one with the normal 10dB boost and cut, and the other with a very subtle 3dB boost and cut - this will be enough (surprisingly) for very minor adjustments such as you might need for day-to-day listening...
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Crossed from: Microphone Circuits | Clicks: 607 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
PC Microphone Preamplifier
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Soundblaster soundcard series (SB16, SB32, AWE32 and AWE64) have all a microphone input designed to be used with the electret microphones which come with the soundcard package (some packages) or with separate microphone designed to be used with SoundBlaster soundcards (there are separate microphones and some monitors have built-in microphones like this). Because the microphone input needs very high input levels it is not suitable to be used with any other micophone type than elecret capsule microphones. If you connect a dynamic microphone (which gives typically few mV voltage) and try to record it you will get very low signal level with lots of noise...
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