Audio Filters Circuits
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This 2-band compressor splits the audio into high and low frequencies and allows independent adjustmen..
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Signetics" type NE575 compander IC is intended primarily for use with battery power supplies of 3 to 7 V (max. 8 V). It..
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By introducing an extra transmission zero to the stopband of a low-pass filter, a sharp roll-off c..
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Many record players unfortunately exhibit two undesired side effects: rumble (noise caused by the motor and the turntable) and other low-frequency spurious signals. The active high-pass Chebyshev filter presented here was designed to suppress those noises.....
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One of the difficulties in the design of higher-order tunable bandpass filters is achieving correct tracking of the..
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Two dual-biquad filter chips and some external components form a multipurpose filter to reconstru..
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A standard dual integrator filter can be constructed using a few CA3080s. By varying LABC, the reso..
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The NE604"s signal-strength indicator section is used, based on an internal logarithmic converter. This enables a linear ..
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This frequency/voltage converter enables calibrations of cassette-deck speed. It records a steady 1-kHz ton..
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Examples of RF and audio ANL circuits. Positive and negative clipping occurs in both circuits. The circuit at A i..
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This circuit detects the presence of audio (voice) on the output of a scanner. If the scanner stops on a "dead carrie..
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The classic state-variable (two-integrator) filter (see Fig. A) is famous for its insensitivity to device parameter tolerances, as well as its ability to provide three simultaneous separate outputs: high pass, bandpass, and low pass. These advantages often....
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This circuit is a variable audio bandpass filter that has a low cutoff variable from about 25 Hz to 700 Hz and a high cutoff variable from 2.5 kHz to over 20 kHz. Rolloff is 12 dB/octave on both high and low ends...
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This variable-frequency, audio bandpass filter is built around two 741 op amps that are connected in cascade. Two 741 op amps are configured as identical RC active filters and are connected in cascade for better selectivity. The filter`s tuning range is....
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The LTC1063 is the first monolithic low-pass filter that simultaneously offers outstanding dc and ac performance. It features internal or external clock tunability, cutoff frequencies up to 50 kHz, 1-mV typical output dc offset, and a dynamic range in....
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A complete schematic diagram of the voice disguiser is shown. Microphone MIC1 picks up the voice signal and feeds it to an audio amplifier, consisting of Ql and Q2, and a few support components. The amplifier has a low-pass gain response that limits the....
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Low-frequency signals produced by transducers, measurement equipment, or data loggers often appear like the first waveform in the figure. The circuit shown operates as a tracking sample-hold, and the transients are replaced in the output by the stored value....
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When the comparator`s output changes its state from low to high, the rising edge of the output pulse, differentiated by the Cl/Rl chain, opens Ql. This blocks comparator via its strobing input and sustains its output in the state for a period of time,....
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The noise limiter circuit has a preamplifier clipper, and a switchable audio bandpass filter. Audio levels in the 5- to 50-mV range are amplified in a preamp to several volts p-p, fed to a clipper, voice band filter, ..
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The circuit as shown gives the bandpass operation the transfer function calculated from FBP(s) = where = 1 + s/Qo>0 + s2/w02. The cut-off frequency, 0, and the Q-factor are given by 0 = g/C and Q = gR/2 where g is the transconductance at room temperature.....
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The filter produces three outputs: high-pass, bandpass, and low-pass. Frequency is linearly proportional to the gain of the two integrators. Two CA3080's, (IC2, 4) provide the variable gain, the resonant frequency being proportional to the current ^. Using....
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The circuit gives a programmable bandpass where both the cut-over frequency and the gain, A, are controlled independently. In the twin-T bridge the resistors R and R/2 are replaced by two double FETs, 430, the channel resistance of the first one in the....
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This limiter improves signal-to-noise ratio. It is connected between the detector output and the audio input (if high impedance) or at some relatively high-impedance section between two audio stages—preferably the low level stages.D1 and D2 can be any....
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In applications where the rejected signal might deviate slightly from the null on the notch network, it is advantageous to lower the Q of the network. This insures some rejection over a wider range of input frequencies. The figure shows a circuit where the Q....
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This circuit is useful where fast signal acquisition and high precision are required, as in electronic scales. The filter's time constant is set by the 2 ohm resistor and the 1 µ capacitor until comparator No. 1 switches. The time constant is then set by....
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The op amp is connected in the inverting mode. Resistor R3 from the output to the inverting input sets the gain and current through the frequency-determining capacitor, CI. Capacitor C2 provides feedback from the output to the junction of Rl and R2. CI and....
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Tl and T2 are 600 to 8 ohm transformers (any transistor radio output transformers with 500 to 4 ohm impedance may be used). Ql is a 2N2222 npn transistor, and Q2 is a 2N2907 pnp transistor. Dl and D2 1N270 signal diodes (HEP 134 or 135). Two transistors,....
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The circuit requires only one dual-ganged potentiometer to tune over a wide range; if necessary over the entire audio range in one sweep. The principle used is that of the Wien bridge, fed from anti-phase inputs. The output should be buffered as shown with a....
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The automatic fader drops at the background music while the narration is in place. The control input through RIO, a preset audio level control, into an emitter-follower buffer stage CQI). The buffer provides high input impedance and ensures that the source....
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36dB/ocf Butterworth filter consists of three sub-ruined structure, each stage box with two filter sections c work zdB/ocf), in order to point a 3dB frequency characteristics n..
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By analyzing the filter capacitance or inductance is filtered DC output is still more or less volatility. In situations requiring high level..
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24dB/oc seven times Butterworth (maximally flat characteristic) constituted by the two filters, each box has two books enough filter (12dB/oct), in order to make a 3dB point tw..