Abstract: Programmable power supplies as used in automatic testing systems (ATS) require three commands from a computer; namely, polarity, gain and analog magnitude. Whether received from a general purpose bus such as the IEEE 488 or other means the commands are in parallel format and must be serialized. The three commands must be recognized and decoded and applied to the appropriate power supplies. The present invention in addition to furnishing the above responses, provides optical isolation to eliminate possible ground loops and other voltage difference problems. One significant simplification comprises the use of sample and hold amplifiers in place of the more conventional latches so that new commands can be accumulated without affecting the response to a prior command.

Abstract: A dynamic load for testing regulated power supplies comprises a pass transistor or transistors which are controlled by current or voltage regulating means operates under current regulation for loading a voltage regulated power supply and under voltage regulation for loading a current regulated power supply. Only a small bias voltage is required to keep the pass transistor in conduction when the terminal voltage of the power supply under test is programmed to zero output voltage. Otherwise the power required for the dynamic load power supply comes from the power supply under test. Programming the dynamic load power supply provides a complete range of loads to the power supply under test. Additionally, feedback from the power supply under test to the dynamic load power supply can cause the latter to simulate a fixed resistor load. The dynamic load power supply replaces a wide range of the conventional power resistors used for regulated power supply testing.

Abstract: Two high voltage power supplies having negative outputs with respect to common are combined to provide positive as well as negative output with respect to common. An operational preamplifier is used as an inverter. The combination includes provision for programming by means of a voltage returned to common making the system compatible with Conventional remote control systems.

Abstract: Two high voltage power supplies programmable by external voltage and each having their positive output terminals as common are combined so that the output has the negative terminal grounded. Also the input programming voltage is applied referenced to ground.

Abstract: In a bipolar regulated power supply, two pass devices (transistors) are connected in a complementary symmetry circuit, one controlling the current from a positive voltage source and the other the current from a negative voltage source. One pass device connected in a first control loop is controlled by a source of input signals and feedback from the output terminal. A second control loop maintains a constant quiescent current in the two pass devices. In order to maintain this quiescent current in the presence of load current, a second feedback to the second loop, sensing load current, is provided.

Abstract: Increased versatility in crowbar overvoltage protection for regulated power supplies is provided by a tracking circuit which allows setting the overvoltage limit at a predetermined increment above a programmable output voltage. In addition provision is made for programming up the crowbar protection circuit rapidly to anticipate the rise of voltage in the main power supply and for delaying the programming down of the protection circuit to allow the main power supply voltage to decay without triggering the protection circuit.

Abstract: A bipolar regulated power supply employing an autotransformer to couple the output to the load is provided with a direct current feedback connected directly across the load. In this way losses in the transformer and leads connecting to the load are compensated for and direct current is eliminated from the output transformer when the input is ac coupled.

Abstract: Power supply turn-on and turn-off transients are eliminated in power supplies employing thermionic vacuum tube pass devices and control amplifiers for controlling the output voltage of the power supply by controlling the conductance of the pass tube or tubes. The elimination of turn-on transients is accomplished by cutting off the pass tube and rendering the control amplifier non-responsive for a predetermined time after the power supply is turned on. The turn-off transients are eliminated by quickly restoring the cut-off of the pass tube and the non-responsive rendering means of the control amplifier very quickly after the turn-off instant of the power supply.

Abstract: A first low voltage power supply having silicon controlled rectifier regulation in the primary of the power transformer, capable of supplying very high direct current, and a second well regulated feedback power supply providing a fixed current in reverse polarity are connected in parallel across a load. The first power supply is feedback controlled to maintain constant current sinking in the second power supply. The second power supply is programmed to regulate the load current or voltage, to provide fine regulation at the load, and to reduce ripple voltage at the load.

Abstract: The power supply output is monitored by voltage and current mode amplifiers, which drive a shunt stabilizer according to control commands and load requirements, the shunt stabilizer altering its conduction, thereby compensating for any tendency of the output to change from its preset level. Simultaneously, the current through the shunt stabilizer is itself monitored by a control amplifier. Depending on the demands made on the shunt stabilizer (which in turn depends on the output requirements), the conduction angle of the control rectifiers in the silicon controlled rectifier phase control circuit are altered. The shunt stabilizer's current is thereby regulated. Two additional amplifiers are used to control the output current. One, the foldback amplifier, receives its input signals from the current mode amplifier and output terminals to transfer the power supply into foldback mode if an overload is present at the output terminals.

Abstract: Two sources of current are applied to a load. One source supplies a constant current which is at least equal to the maximum current to be supplied to the load in one polarity. The second source is in opposition to the first source and is capable of being controlled from zero to a value at least double the value of the constant current. A voltage feedback circuit in combination with a bipolar control signal provides a bipolar voltage across the load having maximum positive and negative voltage excursions equal to the control signal times the feedback circuit gain and current in either direction having a maximum value substantially equal to the constant current value. In this manner a high voltage regulated bipolar voltage can be controlled across a load using one controlled unipolar device while providing class A operation, that is, without cross-over distortion. An important feature of the invention is the positive and negative limiting of both load voltage and load current.

Abstract: In a high current shunt stabilized regulated power supply transients may occur containing too much energy for the shunt stabilizer to safely absorb. The absorber circuit is designed with capacity to absorb normally encountered transients. If the transient lasts longer than a predetermined interval a crow-bar circuit is activated and the power supply is shut down.