Puolentäysiaaltoilmaisin

Puolentäysiaaltoilmaisin, known in English as a half-wave rectifier, is an electronic circuit that converts alternating current (AC) into direct current (DC) by allowing only one half of the AC waveform to pass through. It utilizes a single diode, which is a semiconductor device that permits current to flow in only one direction. When the AC voltage is positive, the diode is forward-biased and conducts, allowing current to pass. When the AC voltage is negative, the diode is reverse-biased and blocks the current.

The output of a half-wave rectifier is a pulsating DC voltage, meaning it consists of a series of positive half-cycles separated by gaps where the current is zero. This pulsating DC is not smooth and contains significant ripple. To smooth out this ripple and produce a more stable DC output, a filter, typically a capacitor, is often added in parallel with the load. The capacitor charges during the positive half-cycles and discharges slowly during the gaps, smoothing the output voltage.

Half-wave rectifiers are simpler and less expensive than full-wave rectifiers but are also less efficient. They are commonly used in low-power applications where a perfectly smooth DC output is not critical, such as in simple battery chargers, signal demodulation in radio receivers, and as part of more complex power supply circuits. The output frequency of the rectified signal is the same as the input AC frequency.