Transistorized load control circuit comprising high- and low-parallel voltage sources

Claim 2

A load control circuit for operating a load circuit, comprising: an input terminal for receiving input control voltage conditions: a first source of potential; a second source of potential; a source of reference potential; a first transistor having base, collector, and emitter, the base being coupled to the input terminal and the collector being coupled to the first source of potential; a second transistor having base, collector, and emitter; first diode means connected in series with the emitter of the first transistor and the collector of the second transistor, said first diode means having a conducting state and a nonconducting state; second diode means connected in series with the emitter of the first transistor and the base of the second transistor, said second diode means having a conducting state and a nonconducting state; third diode means connected in series with the collector of the second transistor and the second source of potential, said third diode means having a conducting state and a nonconducting state; means for connecting a load circuit in series with the emitter of the second transistor and the source of reference potential; said second transistor being operable in a conducting state, said first diode means being operable in its nonconducting state, and said second and third diode means being operable in their conducting states in response to a first input control voltage condition at the input terminal, whereby current is supplied from the second source of potential to the load circuit via the conducting third diode means and the conducting second transistor; and said first transistor being operable in a conducting state, said first and second diode means being operable in their conducting states, and said third diode means being operable in its nonconducting state in response to a second input control voltage at the input terminal, whereby current is supplied from the first source of potential to the load circuit via the conducting first transistor, the first diode means, and the collector-emitter circuit of the second transIstor.

Claim 3

A load control circuit in accordance with claim 1 wherein: the first input control voltage condition forward biases the second diode means and the base-emitter junction of the second transistor; and the second input control voltage condition forward biases the base-emitter junction of the first transistor and the first and second diode means.

Claim 4

A load control circuit in accordance with claim 1 wherein: the first source of potential is a positive high-voltage source; the second source of potential is a positive low-voltage source; the source of reference potential provides a potential which is negative with respect to the low-voltage source; the first and second transistors are NPN-transistors; the first diode means comprises a diode having its anode coupled to the emitter of the first transistor and its cathode coupled to the collector of the second transistor; the second diode means comprises a diode having its anode coupled to the emitter of the first transistor and its cathode coupled to the base of the second transistor; and the third diode means comprises a diode having its anode coupled to the second source of potential and its cathode coupled to the collector of the second transistor.

Claim 5

A load control circuit in accordance with claim 1 wherein: the first source of potential is a positive high-voltage source; the second source of potential is a positive low-voltage source; the source of reference potential provides a potential which is negative with respect to the low-voltage source; the first and second transistors are NPN-transistors the first diode means comprises a diode having its anode coupled to the emitter of the first transistor and its cathode coupled to the collector of the second transistor; the second diode means comprises a plurality of diodes connected in a series aiding arrangement, the anode of the first one of the plurality of diodes being coupled to the emitter of the first transistor and the cathode of the last one of the plurality of diodes being coupled to the base of the second transistor; and the third diode means comprises a diode having its anode coupled to the second source of potential and its cathode coupled to the collector of the second transistor.

Claim 6

A load control circuit for operating a load circuit, comprising: an input terminal for receiving input control voltages: a high-voltage source; a low-voltage source; a source of reference potential; a first transistor having base, collector, and emitter, the base being connected directly to the input terminal and the collector being connected directly to the high-voltage source; a second transistor having base, collector, and emitter; a first diode connected in series with the emitter of the first transistor and the collector of the second transistor, said first diode being poled for easy current flow between the emitter of the first transistor and the collector of the second transistor; a second diode connected in series with the emitter of the first transistor and the base of the second transistor, said second diode being poled for easy current flow between the emitter of the first transistor and the base of the second transistor; a third diode connected in series with the high-voltage source and the collector of the second transistor, said third diode being poled for easy current flow between the high-voltage source and the collector of the second transistor; said load circuit being adapted to be connected in series with the emitter of the second transistor and the source of reference potential; said second transistor and said second and third diodes being operable in their conducting states and said first diode being operable in its nonconducting state in response to a control voltage at the input terminal having a value equal to the sum of the values of the forward-bias base-emitter voltage of the first transistor, the Forward-bias voltage of the second diode, and the forward-bias base-emitter voltage of the second transistor-but less than the value of the low-voltage source, plus the value of the forward-bias base-emitter voltage of the first transistor, plus the value of the forward-bias voltage of the first diode, minus the value of the forward-bias voltage of the third diode-whereby current is supplied from the low-voltage source to the load circuit via the conducting third diode and the conducting second transistor, and said first transistor and said first and second diodes being operable in their conducting states and said third diode being operable in its nonconducting state in response to a control voltage at the input terminal having a value equal to or greater than the value of the low-voltage source, plus the value of the forward-bias base-emitter voltage of the first transistor, plus the value of the forward-bias voltage of the first diode, minus the value of the forward-bias voltage of the third diode, whereby current is supplied from the high-voltage source to the load circuit via the conducting first transistor, the conducting first diode, and the collector-emitter circuit of the second transistor.

Claim 7

A load control circuit for operating a load circuit, comprising: an input terminal for receiving input control voltages: a high-voltage source; a low-voltage source; a source of reference potential; a first transistor having base, collector, and emitter, the base being connected directly to the input terminal and the collector being connected directly to the high-voltage source; a second transistor having base, collector, and emitter; a first diode connected in series with the emitter of the first transistor and the collector of the second transistor, said first diode being poled for easy current flow between the emitter of the first transistor and the collector of the second transistor; a second diode connected in series with the emitter of the first transistor and the base of the second transistor, said second diode being poled for easy current flow between the emitter of the first transistor and the base of the second transistor; a third diode connected in series with the high-voltage source and the collector of the second transistor, said third diode being poled for easy current flow between the high-voltage source and the collector of the second transistor; said load circuit being adapted to be connected in series with the emitter of the second transistor and the source of reference potential; said second transistor and said second and third diodes being operable in their conducting states and said first diode being operable in its nonconducting state in response to a control voltage at the input terminal having a value equal to the sum of the values of the forward-bias base-emitter voltage of the first transistor, the Forward-bias voltage of the second diode, and the forward-bias base-emitter voltage of the second transistor-but less than the value of the low-voltage source, plus the value of the forward-bias base-emitter voltage of the first transistor, plus the value of the forward-bias voltage of the first diode, minus the value of the forward-bias voltage of the third diode-whereby current is supplied from the low-voltage source to the load circuit via the conducting third diode and the conducting second transistor, and said first transistor and said first and second diodes being operable in their conducting states and said third diode being operable in its nonconducting state in response to a control voltage at the input terminal having a value equal to or greater than the value of the low-voltage source, plus the value of the forward-bias base-emitter voltage of the first transistor, plus the value of the forward-bias voltage of the first diode, minus the value of the forward-bias voltage of the third diode, whereby current is supplied from the high-voltage source to the load circuit via the conducting first transistor, the conducting first diode, and the collector-emitter circuit of the second transistor.

Claim 8

A load control circuit in accordance with claim 5 wherein: the high-voltage and low-voltage sources are positive voltage sources: the first and second transistors are NPN-transistors and the source of reference potential is ground potential.