Electrical4U What is QAM (Quadrature Amplitude Modulation)? QAM (Quadrature Amplitude Modulation) combines phase and amplitude modulation on one radio channel. It sends data by changing both the amplitude and the phase of a carrier. Two carriers that sit 90 degrees apart share that channel, so more bits fit in the same bandwidth. An older name for … Read more
What is Dielectric Grease? Dielectric grease is an electrically insulating grease used to seal out moisture and contamination, reduce corrosion and lubricate connector seals. Many products are silicone-based, but dielectric connector greases can use other base oils. A typical silicone product combines polydimethylsiloxane fluid with a silica thickener. It repels water and has high electrical … Read more
What is Permeance? Permeance relates magnetic flux to magnetomotive force in a lumped magnetic circuit. It is the reciprocal of reluctance. This page denotes it by P. Flux is proportional to permeance only when the applied magnetomotive force and magnetic operating conditions are fixed. $ Permeance (P) = \frac {1} {Reluctance(S)} $ For a fixed … Read more
What is Reluctance? Magnetic reluctance is the ratio of magnetomotive force to magnetic flux in a lumped magnetic circuit. It depends on the path geometry and permeability, so it describes the complete magnetic path or one of its sections rather than a material alone. In an electrical circuit, resistance relates voltage to current and dissipates … Read more
What is an LC Circuit? An LC circuit is an electrical circuit containing two passive circuit elements: an inductor (L) and a capacitor (C). Resonant applications also call it a tank or tuned circuit. Its connection to a source and load determines whether it behaves as a resonator, filter or impedance network. An ideal LC … Read more
What is an RC Circuit? An RC circuit, or resistor-capacitor network, is an electrical circuit containing the passive circuit components of a resistor (R) and capacitor (C). Depending on its connection and output point, the network can shape signals, set timing or store and release energy while driven by a voltage source or current source. … Read more
What is Impedance Matching? Impedance matching selects or transforms source, network and load impedance for a stated goal. A conjugate match maximises available power transfer, while matching a load to a transmission line’s characteristic impedance minimises reflection at that load. A practical source, such as an amplifier or generator, has an output impedance. A load … Read more
What is Load Factor? In electrical engineering, Load Factor is the ratio of average load to the maximum demand during the same period. Because average load equals total energy divided by time, the ratio can also be calculated from energy use, maximum demand and the length of the period. It may be calculated for a … Read more
What is a Butterworth Filter? A Butterworth filter has a magnitude response that is maximally flat at the centre of its passband. Engineers therefore call it a maximally flat magnitude filter. British physicist Stephen Butterworth described the response in his 1930 paper On the Theory of Filter Amplifiers. The low-pass Butterworth magnitude decreases monotonically from … Read more
What is a Bleeder Resistor? A bleeder resistor is a resistor connected across a power-supply output or storage capacitors. It provides a defined discharge path after power is removed. In some supplies, it also provides a minimum load while the equipment is on. A charged capacitor can retain a hazardous voltage after the switch is … Read more