Automatic voltage regulation responsive to input voltage variations

Claim 1

An adjustable voltage system comprising an adjustable voltage means connectable to a source of alternating current for producing an output voltage and having a mechanical movable means which is movable to adjust the value of the output voltage, a reversible motor connected to said movable means and having a first channel which when energized moves the movable means in a direction to increase the value of output voltage and a second channel which when energized moves the movable means in the other direction to decrease the value of the output voltage, means for controlling the energization of each channel of the motor including a semiconductor means in each channel, each of said semiconductor means being normally nonconducting but being rendered conducting upon receipt of a triggering signal and a motor control circuit having settable means for selecting a desired value of output voltage and for providing a triggering signal to only one of said semiconductor means upon the value of the output volTage deviating from the desired value; in which the motor control circuit includes means for producing an error signal related to the value of the output voltage, said error signal being of one or an opposite polarity and amplifying means for receiving the error signal and producing a triggering signal to one semiconductor means when the error signal is of one polarity and a triggering signal to the other semiconductor means when the signal is of the opposite polarity; in which the amplifying means includes a dual channel integrated amplifier having two independent amplifiers with each amplifier being rendered operative only upon application of a signal of one polarity, the error signal appears across a pair of leads and means applying one lead to one amplifier and the other lead to the other amplifier whereby only the lead having the one polarity is capable of producing a triggering signal by being rendered operative; in which the amplifier means includes a pair of transistors with one transistor being operatively interconnected to one semiconductor means and the other transistor being operatively connected to the other semiconductor means with each operative connection including a pulse transformer and in which said transistors and said pulse transformer are connected to a source of unidirectional pulsating electric power; in which the unidirectional pulsating electric power consists of half-wave rectified alternating current and in which the motor is energized through its semiconductors from a source of alternating current that is substantially in phase with the half-wave rectified alternating current; and in which each semiconductor means is normally nonconducting for each cycle and is rendered conducting only by a triggering pulse that occurs during a half-cycle of the alternating current, in which the semiconductor means maintains conduction for the other half-cycle of the alternating current and in which the triggering signal is applied early in the halfcycle whereby said motor is energized for substantially the complete alternating current cycle.