A hand tool of the toggle link or vice grip type provided with structure operative to oppose opening movement of the handles when the latter are oriented relative to the toggle linkage in locking condition in the absence of any reactive force from a workpiece. Such structure takes two basic forms, namely, (a) the compression member of the toggle linkage being swivelly connected at its opposite ends to the handles to hold its swivel connections spaced a substantially constant amount at all times,...

A locking plier employing the over-center locking principle. A movable jaw is pivotally connected to a rigid handle which terminates in a rigid jaw and a movable handle is pivotally connected to the movable jaw. A sliding adjuster having an opening therethrough is positioned over the rigid handle and teeth along the opening mate is locking engagement with teeth along the rigid handle. A link pivotally connects the sliding adjuster and the movable handle to permit the over-center locking position...

A self-adjusting locking wrench having a first jaw means and second jaw means movably connected thereto. A first elongated handle portion is fixed to and extends rearwardly from the first jaw means and a second handle portion is pivotally connected to the second jaw means. An elongated cam bar is slidably mounted within the first handle portion and has a forward cam surface for locking engagement with a portion of the second jaw means. A link extends between the second handle portion and the rea...

A synchronous rectifier circuit employs therein a pair of synchronously-operated switches, each switch being coupled between a separate respective input terminal and an output terminal of the circuit. One of the synchronously-operated switches is gated ON when a voltage applied across the synchronous rectifier circuit input terminals is of one polarity, and is gated OFF when current therein becomes substantially zero. The second switch is gated ON when a voltage applied across the input terminal...

The present invention discloses an AC/DC converting control circuit, which is used in transformerless AC/DC converting apparatuses. The control circuit primarily includes a current-switch circuit, a duty-control circuit and a load-current limiting circuit. When electrically connecting with a load and a voltage source in series, the control circuit of the present invention reduces the oscillation during on/off switching and provides a stable output current.

An on-line UPS has radio frequency filter, rectifier filter, battery, detecting circuit, controlling circuit and trigger circuit, and its efficiency approximate a hundred percent. No matter what commercial power is failure, or its voltage is too high or too low, it is able to keep voltage output within normal range. When commercial power is abnormal, it supplies power with battery by automatic switchover, and its response time is zero millisecond. The structure of the present invention is simple...

A power supply circuit and a switched-mode power supply with a power supply input circuit are proposed. Known power supply circuits comprise a rectifier supplied with an AC voltage and a first smoothing capacitor. To provide a circuit which is suitable for operation over a wide voltage range, it is proposed that at least a second capacitor be provided which is connected by a switching element to the load terminals so that, when the voltage at the load terminals drops below a voltage threshold, t...

The phase control arrangement of a valve converter according to the invention comprises a control signal former having one input connected to the valve converter and another input connected to a reference signal unit. The output pulse from the control signal former is fed, concurrently with the output signal of a sawtooth oscillator, to a zero element having its output connected, via a phase limiter, to the input of the control pulse generator. Control pulses are distributed among the converter ...

A high power factor AC/DC converter is disclosed. In the AC/DC converter in which a rectifying circuit RC1 rectifies a commercially available AC power supply Ei, a switching device turns on and off so that the rectified voltage is applied across the primary winding n1 of the transformer Tr1 to provide a high frequency voltage across the secondary winding n2, and the high frequency voltage is rectified by means of a rectifying circuit connected across the secondary winding so as to generate a pre...

An improved electric power conversion system comprising a multi-phase bridge circuit composed of semiconductors such as thyristors and an associated firing circuit. It is so constructed that: if the AC input current Iac flowing in the bridge circuit is equal to or larger in value that the DC output current Idc flowing out of the bridge circuit, it will be decided than an inner defect or fault is caused, and possible expansion of inner defect will be prevented by disabling the firing circuit to e...