Capacitive coupling

This technique helps to isolate the DC bias settings of the two coupled circuits.A coupling capacitor's ability to prevent a DC load from interfering with an AC source is particularly useful in Class A amplifier circuits by preventing a 0 volt input being passed to a transistor with additional resistor biasing; creating continuous amplification.However, if a signal passing through the coupling capacitance has a frequency that is low relative to the RC cutoff frequency, voltages can develop across the capacitor, which for some capacitor types results in changes of capacitance, leading to distortion.A gimmick loop is a simple type of capacitive coupler: two closely spaced strands of wire.If a high-gain amplifier's output capacitively couples to its input it may become an electronic oscillator.
Capacitive coupling from high-voltage power lines can light a lamp continuously at low intensity.
Capacitive coupling from high-voltage power lines can light a lamp continuously at low intensity.
Polyester film capacitors , commonly used for coupling between two circuits.
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