Showing posts with label Filters. Show all posts

Wideband Two Pole High Pass Filter

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An equivalent low pass filter is similarly obtained by capacitance and resistance transformation.

The Rectifier and Filter Circuit

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Here is simple Electronic Project of the basic power supply and filter circuit.

This circuit provides about 294 volts at a 50mA load and nominal line. It also produces about 800mV of ripple. At 20% low line, this voltage drops to 232 volts, at -10% low line, the voltage is 260 volts. At +10% high line, the output goes to 320 volts, and at 20% high line, the output climbs to 355 volts. The voltage vs load current looks like this:

Notice that at load currents below 40mA, the voltage rises rapidly. This is due to the LC filter. At those currents, the critical current for choke input filtering is not satisfied. This is done purposely so we can see the effects of different regulators.

Notch Filter with Both High and Low Pass Filters

This simple and low pass notch filter circuit. A variable notch filter with both high and low pass filters.

Circuit Diagram:

Notes:
At first glance this circuit looks fairly complex, but when broken down,can be divided into high pass and low pass filter sections followed by a summing amplifier with a gain of around 20 times. Supply rail voltage is +/- 9V DC. The controls may also be adjusted for use as a band stop (notch) filter or band pass filter.

Wideband Two-Pole High-Pass Filter Schematic

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The circuit provides a 10MHz cutoff frequency. Resistor R3 ensures that the input capacitance of the amplifier does not interact with the filter response at the frequency of interest. An equivalent low pass filter is similarly obtained by capacitance and resistance transformation.

Wideband Two-Pole High-Pass Filter Schematic

4.5 Mhz Notch Filter Schematic

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Component value sensitivity is extremely critical, as are temperature coefficients and matching of the components. Best performance is attained when perfectly matched components are used and when the gain of the amplifier is unity.

4.5 Mhz Notch Filter Schematic

To illustrate, the quality factor Q is very high as amplifier gain approaches 1 with all components matched (in fact, theoretically it approaches infinity) but decreases to about 12.5 with the amplifier gain at 0.98.

ADSL and DSL Inline Phone Filter

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When the ADSL and PSTN works on the same line at the same time, a problem the electronics in a normal telephone for high frequency signals ADSL: ADSL signals can be reduced (with high capacity intercom can be resonances in the phone, impedance mismatch ) and ADSL signals can be heard as the sound on some phones (electronic phone demodulates RF signal is out of range voting frequency noise). Just to keep these systems and stop interfering with each other, it is necessary for the two components of the telephone in your home to separate.

ADSL and DSL Inline Phone Filter Circuit diagram

This is where the filter / splitter comes in. The ADSL POTS splitter / filter allows you to take full advantage of the frequency 1.1 MHz copper line to take, stopping the ADSL and phone systems interfere with each others. An ADSL filter is normally a small plastic box with a short cable that connects to your telephone jack and two outputs, one for your ADSL modem and a telephone. Some filters have an exit by calling them. ADSL filter to the frequency band for each of the outlets, telephone or ADSL to select just the right tire and sending in the socket. The output of the phone is not receiving phone frequencies (from DC to 3.4 kHz) and the output is higher and ADSL freuquencies (above 25 kHz).

For good system performance, it is very important that all your other phone equipment is separated from the ADSL signals using a splitter / filter – This equipment includes telephones, answering machines, “normal” modems, etc., etc.

300-3400 Hz Second Order Speech Filter

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Using two op amps, this filter is designed for second-order response. It has a bandpass of 300 to 3400 Hz, for applications in speech or telephone work.

300-3400 Hz Second Order Speech Filter Schematic

Twin-T RC Notch Filter

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The two T-notch filter can be used to block unwanted frequencies or if placed in an op amp as a bandpass filter. the notch frequency occurs where the capacitive reactance equals the resistance (Xc = R) and if the values are close, the attenuation can be very high and the notch frequency virtually eliminated,Insertion of the filter depends on the load, the output is connected to the subject so that the resistors must be of much lower value than the load for minimal loss.

Twin-T RC Notch Filter Circuit diagram

For audio frequencies, the filter may act as a bass and treble boost circuit by attenuating the midrange. With 1.5K resistors and capacitors 0.1 uF, the band is in stop-10dB 500 Hz to 2 kHz. The depth and breadth of the reaction can be slightly adjusted to a value of 0.5 R and adding some resistance at the C-values,If the circuit is an operational amplifier is used as a bandpass filter, the response should be reduced to avoid oscillation.