The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 19, 1982
Filed:
Jan. 17, 1980
Luciano Franzolini, Milan, IT;
Sp. El. s.r.l., Milan, IT;
Abstract
A chopping transistor connected across a d-c power supply, in series with a load such as a motor, has its base connected to an output of an oscillator generating a train of voltage pulses V.sub.1 by which that transistor is alternately turned on and off. A threshold sensor emits a series of monitoring pulses V.sub.2 of the same polarity as the conduction-establishing control pulses V.sub.1 when the collector/emitter voltage of the transistor surpasses a certain limit; the joint appearance of signals V.sub.1 and V.sub.2 at respective inputs of an AND gate gives rise to an off-normal signal V.sub.3 which, if of extended duration, passes a delay circuit to act as an alarm signal V.sub.4. A memory tripped by that alarm signal emits a permanent disconnect signal V.sub.5 which either blocks the oscillator or fires a thyristor in shunt with the transistor whereby a fuse in series therewith is blown. The transistor may be one of four such transistors inserted in respective arms of a bridge, with two oscillators each driving a pair of these transistors and a common fuse in series with both pairs.