Circuit knowledge

Thursday, September 4, 2014

Subwoofer Filter Circuit

General Description

This subwoofer active filter circuit is a 24 dB octave filter with a Bessel character and cutoff frequency of 200 Hz. So, if you are interested in experimenting with audio circuits in subwoofer range, this circuit is for you. In subwoofer range, all audio frequencies below 200 Hz can be fed to a single speaker box since the human directional perception of sound diminishes at this frequency range. The normal stereo signals above 200 Hz can be fed to 2 satellite speakers. How does the subwoofer filter works: A1 and A2 buffer the signals coming from right and left channels. Opamp combinations A2/A4 and A9/A10 function as the highpass filters. The outputs are then connected to the final amplifiers of the battelite boxes. Signals from both channels are fed to A5. Opamps A6/A7 function as the lowpassfilter, A8 as the output amplifier for the subwoofer signal. The signal level can be balanced between the subwoofer and the satellite lines. The power needed for this filter circuit must ne a symmetrical power supply. The opamps can have either JFET or bipolar inputs.

Cicuit Diagram

Tuesday, August 26, 2014

Voice Bandwidth Filter Wiring diagram Schematic

This schema passes frequencies in the 300Hz - 3.1kHz range, as present in human speech. The schema consists of cascaded high-pass and low-pass filters, which together form a complete band-pass filter. One half of a TL072 dual op amp (IC1a) together with two capacitors and two resistors make up a second-order Sallen-Key high-pass filter. With the values shown, the cut-off frequency (3dB point) is around 300Hz. As the op amp is powered from a single supply rail, two 10kO resistors and a 10µF decoupling capacitor are used to bias the input (pin 5) to one-half supply rail voltage.

Circuit diagram:

Voice Bandwidth Filter Circuit Diagram

The output of IC1a is fed into the second half of the op amp (IC1b), also configured as a Sallen-Key filter. However, this time a low-pass function is performed, with a cut-off frequency of about 3.1kHz. The filter component values were chosen for Butterworth response characteristics, providing maximum pass-band flatness. Overall voltage gain in the pass-band is unity (0dB), with maximum input signal level before clipping being approximately 3.5V RMS. The 560O resistor at IC1bs output provides short-schema protection.

Source by : Streampowers

Monday, August 25, 2014

Voltage Controlled Filter SSM2044P Wiring diagram Schematic

Voltage Controlled Filter at this schema the SSM2044 IC is used, a 4 pole voltage controlled filter designed for electronic music applications. On-chip voltage control of resonance allows direct and easy interfacing with programmers and controllers. The IC features extended control range, low noise, and high control rejection. The filter can also be used as a low distortion sinewave oscillator. No external ladder network is required making the device ideal in polyphonic applications.

Voltage Controlled Filter SSM2044P Circuit Diagram

Friday, August 15, 2014

Tunable Bandpass Filter Wiring diagram Schematic

One of the difficulties in the design of higher-order tunable bandpass filters is achieving correct tracking of the variable resistors in the RC networks. The use of switched capacitor networks can obviate that difficulty, as is shown in this filter. The filter can be divided roughly into two stages: an oscillator that controls the electronic switches arid the four phase-shift networks that provide the filtering proper.

Tunable Bandpass Filter Circuit Diagram

The oscillator, based on a 555, generates a pulsating signal whose frequency is adjustable over a wide range: the duty factor varies from 1:10 to 100:1. Electronic switches ESI through ES4 form the variable resistors whose value is dependent on the frequency of the digital signal. The operation of these switches is fairly simple. When they are closed, their resistance is about 60 ; when they are open, it is virtually infinitely high. a switch is closed for, say, 25% of the time, its average resistance is therefore 240 . `Varying the open:closed ratio of each switch varies the equivalent average resistance.

The switching rate of the switches must be much greater than the highest audio frequency to prevent audible interference between the audio and the clock signals. The input signal causes a given direct voltage across CI, so the op amp can be operated in a quasisym-metric manner, in spite of the single supply voltage. The direct voltage is removed from the output signal by capacitor C10. The fourth-order filter in the diagram can be used over the entire audio range and it has an amplification of about 40, although this depends to some extent on the clock frequency. The bandwidth depends mainly on the set frequency. The schema draws a current of not more than 15 mA.

Wednesday, August 13, 2014

Build a Universal Active Filter Wiring diagram Schematic

The Universal Active Filter Circuit Diagram 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 trans conductance at room temperature. Interchanging the capacitor C with the resistor R at the input of the schema high-pass operation is obtained. A low-pass filter is obtained by applying two parallel connections ctf R and C as shown in Fig. 2. The low-pass operation may be much improved with the schema as given in Fig. 3. Here the gain and Q may be set up separately with respect to the cut-off frequency according to the equations Q = 1/fB = 1 + R2/R!, A = Q2 and 0 = g ffi/C.

Build a Universal Active Filter Circuit Diagram