Definition: Type of semiconductor used for switching or control of current e.g. silicon-controlled rectifier. * At a certain threshold voltage, it allows current to flow but allowing passage only to a certain portion of a wave-form input, depending on the bias that is set. Unsung heroes of the Revolution: Part ... Thyristors have a case for being heroes of environmental friendliness for the amount power, particularly that of terribly expensive and polluting battery power, which they save. For they are used extensively in photography as an energy-efficient means of controlling flash output: before thyristors ruled the roost, if you didn't use all the charge in a flash-gun's capacitor, it was wasted, drained to the cosmos. Good ole T trims energy output into a flash-unit with hardly any loss and keep the squeeze on capacitors so they can power the flash easily, without having to be charged up from scratch.

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