Current limiter for power supplies

Claim 1

A current-limiting circuit for power supplies, comprising: a. a power source; b. a load; c. a first transistor having its emitter-collector circuit connected in series with said load; d. a second transistor having its emitter-collector circuit connected directly in parallel with the base-emitter circuit of said first transistor; e. the base-emitter circuit of said second transistor being connected substantially directly in parallel with the emittercollector circuit of said first transistor; f. whereby said first and second transistors, when conducting, essentially short out each other''s base-emitter circuit; g. base drive limiting resistor means interposed in said baseemitter circuit of said second transistor; h. the resistance Rd of said base drive limiting resistor means being smaller than the value 2Rb, wherein 2 is the beta of said second transistor, and Rb is the resistance of said bias resistor means, so as to provide a switching hysteresis in which the load current, as the load resistance goes toward zero, suddenly drops from a limit value to a substantially lower value and then increases again to a final value less than said limit valve, said load current, as said load resistance increases again, diminishing until it suddenly jumps to a higher value less than said limit value; i. whereby tripping of the circuit is prevented until the overload is substantial, yet restoration of normal operation of the circuit is prevented until the load returns to near normal.