resistor capacitor (rc) circuits overview and uses
Resistor Capacitor (RC) Circuits Overview and Uses
A resistor capacitor circuit, or RC circuit, is an electrical circuit composed of resistors or capacitors that may be driven by a voltage or current source. They are designed to prevent or significantly minimize the occurrence of arcing and noise generation in relay and switch contacts. The simplest type of RC circuit is a first order RC circuit and consists of one resistor and one capacitor component. RC circuits can be used to filter a signal by blocking certain frequencies and allowing other ones to pass through. The two most common types of RC filters are high-pass filters and low-pass filters. Band-pass filters and band-stop filters typically require RLC filters, though they can be made with RC filters.
There are three basic linear passive lumped analog circuit components, those being the resistor, capacitor, and the inductor, they may be combined in an RC circuit, RL circuit, LC circuit, or RLC circuit, with the acronyms representing which components are being used. These circuits exhibit a wide array of types of behaviors fundamental to much of analog electronics.
A resistor capacitor network consists of specially designed precision capacitors and resistors connected in a series. Spark discharges and induced noise are absorbed over a wide range by the accumulation characteristics and impedance of the capacitor, while the RC time constant delays and modifies surge voltage and oscillations. To store surge voltages and current energy while providing protection against inductively induced potentials, RC networks are made from dielectric material that provides a high degree of voltage resistance strength. Non-inductive RC network types also exist to ensure a high degree of protection against pulse potentials. RC circuits are packaged in cases that meet or exceed the flammability requirements of UL94VO standards.
The main features of RC filters are single-to-multiple combination, metal cans & epoxy cases, solid and stranded wire leads with differing length and terminations, DIN rail compatibility, CE compatibility, and environmental and governmental compliance. RC circuits are used in a broad range of commercial and industrial applications. Among these are machine tools, switchgear, motor controllers, computers, telecommunications, automated equipment, industrial appliances, elevators & escalators, and more.
Determining the value of a resistor capacitor is an important aspect of using the device. To do this, there are three steps. First, clip directly into the circuit. Then, with the aid of the storage oscilloscope, select and match various combinations of resistors and capacitors to optimize spike reduction and/or reduce EMI levels. Once the combination is determined, refer to the device’s manual to determine the correct value.
Finally, it is sometimes required to synthesize an RC circuit from a given rational function. For synthesis to be possible in passive elements, the function must be a positive-real function. When synthesizing an RC circuit, all critical frequencies (poles and zeros) must be on the negative real axis and alternate between poles and zeros with an equal quantity of each. Additionally, the critical frequency closest to the origin must be a pole, assuming the rational function represents an impedance instead of an admittance.