Constant gain, constant Q, variable frequency filter which provides simultaneous low-pass, bandpass, and high-pass outputs..
A differential amplifier makes an excellent audio clipper and can provide precise, symmetrical clipping. The circuit shown commences clipping at an input of 100 mV. The output commences clipping at Â±3 V. Matching Q7 and Q2 is necessary for good symmetrical clipping.
The notch filter can be added to just about any receiver to attenuate a single frequency by more than 30 dB...
This frequency/voltage converter enables calibrations of cassette-deck speed. It records a steady 1-kHz ton..
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 offset the fact that a quad operational amplifier is needed to implement the circuit. A modification of the classic scheme that applies the input voltage via amplifier UD, rather than UA provides a bandpass output with.....
This filter circuit which uses LM1458 or similar op amp has a response of 300 Hz to 3.4 kHz with 12 dB/octavc roll-off outside the pass band. Sqction A is the high-pass one, followed by low-pass section B. ..
The above realization of a type 03 receive filter is accomplished using eight OP-OS"s. As can be seen from the response curve, the >30dB attenuation in the stop band requirement has been met. In addition, the noise performance of
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This is a second-order, low-pass filter with programmable cutoff frequency. This circuit should be driven from a low-source impedance since there are paths from the output to the input through the unselected networks. Virtually any filter function which can be constructed with a conventional op amp can be made programmable with the HA-2400. ..
This circuit is selective for the tuning adjustment between two closely spaced tones audio. The frequency is dependent on the selective value capacitors and resistors in the feedback circuit between the collector and base of Q1. With the values shown, the frequency can be "tuned" to a hundred cycles or so-around 650 Hz Ri and R2 should be grouped. R3 potentiometer transmitter determines the sharpness of the response curve.
An optoisolator is used as an attenuator in this circuit. When the LM386 draws more current on audio signals, the 2N3638 turns on, which biases the optoisolator on,..
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 impedance is low enough to drive the rectifier and smoothing circuit, consisting of DI, D2, and C5. The smoothed output drives a simple LED circuit. LD and R8 form an IR input pad through which the output is fed through.....
This notch filter, which operates at up to jected..
The PN4391 provides a low Rds(on) (less than 30 ohms)..
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. The filter has a 0.1-dB ripple characteristic and a cut-off point of 18 Hz. The choice of a Chebyshev filter might not seem optimum for audio purposes, but because of its 0.1-dB ripple in the pass band it behaves very.....
The active filter is a state variable filter with bandpass, high-pass and low-pass outputs..
This second-order low-pass filter uses a 741 op amp and is tuneable from 2.5 kHz to 25 kHz. This circuit is useful in audio and tone control applications...
The first stage is a simple buffer used to isolate the signal source from the attenuator stages to follow. Each of the subsequent stages is preceded by a voltage divider formed by two resistors and CMOS switch. Provided that the CMOS switch for each stage is closed, the drive signal will be attenuated according to the basic voltage divider relationship at each stage. In the event a switch is open, nearly all of the signal strength will be passed to the next stage.....
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 voice frequencies to 5 kHz or lower. The voice signal is then fed to the input of the first, balanced modulator, which is comprised of Ul-a, Ul-b, U2-a, and U3-a. The output of the first 4-kHz oscillator, built around U3-f.....
Figure 1 illustrates the simplified block diagram of a typical high-speed data converter system. The system consists of a bandpass filter, ADC, high-frequency clock, high-speed storage device, and post processing unit. Aside from the MAX104, the high-frequency clock plays a significant role in determining the accuracy of a high-speed data converter. This high frequency, low-phase-noise clock is a combination of a high frequency voltage-controlled oscillator (U1), a.....
The purpose is supposedly to account for the fact that human hearing is less sensitive at low and high frequencies than in the upper midrange, and that this variation is dependent upon the sound intensity (SPL). The Fletcher-Munson curve (as it is commonly known, and reproduced below) shows the variation, and it is clear that any loss of sensitivity is highly dependent upon the actual SPL. The idea that a single filter can represent this at all levels is clearly wrong, but.....
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