Clive W. Humphris

**PASSIVE FILTERS: RC Low Pass Passive Filter. **

Typical examples of filter circuits are used for AC smoothing in a power supply , separating the frequencies within a loudspeaker enclosure, i.e bass treble and mid range or the signal processing in a radio or television receiver. Filters act as an electronic gateway by allowing some frequencies to pass whilst others are rejected.

A low pass filter has a pass band situated below fc which is the cut-off frequency. Frequencies above this point being gradually attenuated. At fc the reactance of C will equal the series resistance, thus forming a voltage divider network. At frequencies below fc the reactance of C will be high and a greater part of the input will be available as output.

For frequencies greater than fc, Xc falls relative to R thereby reducing Vout. Filter response is expressed in decibels as the output is relative to the input, using the formula for voltage.

- Table of Contents
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- Basic Electronics
- Conductor And Insulator
- Resistor Value Test
- Simple Dc Circuits
- Types Of Switching
- Variable Voltages
- Ohm's Law
- DC Voltage
- DC Current
- Series and Parallel Resistors
- AC Measurement
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- AC Theory
- RCL Series
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- Capacitance
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- Inductance
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- Impedance
- Radio and Communication
- Tuned Circuits
- Attenuators
- Passive Filters
- Active Filters
- Oscillators
- Circuit Theorems
- Complex Numbers
- DC Power
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- Silicon Controlled Rectifier
- Power Supply
- Voltage Regulation
- Electro-Magnetism
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- Three Phase Systems
- Energy Transfer and Cost
- Atomic Structures
- Diode Theory
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- Transistor Theory
- Bipolar Transistors
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- Active Transistor Circuits
- Field Effect Transistors
- Basic Operational Amplifier
- Op-Amp Theory
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- Sum and Difference Amplifiers
- Analogue Multi-Meter
- Component Testing