Abstract: The new instrument is a three piece frame which folds into a compact, hand carried device and when opened forms a track spanning frame. In its open position the frame carries on its midsection an electronic levelmeter and the track gage meter or indicator.The main frame consists of four arms. Two of these arms are hinged to fold on themselves for carrying and opening into a straight line for making measurements of gage and level. The other two arms fold back onto the first two for carrying and open at a predetermined angle to support the first mentioned arms in a perpendicular relationship to the track being observed.Under the three outer ends of the arms are feeler contacts. The two on the angled arms are fixed to ride on the inner edge of one of the tracks being measured. A third feeler contact is carried under the end of the single and oppositely extended arm.

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: A blower motor providing vacuum as, for example, for a magnetic tape handler, is programmed to provide a constant vacuum in an environment of changing altitudes. The blower motor is controlled by a pressure transducer which speeds up the motor as the altitude is increased and slows down the motor as the altitude is decreased.

Abstract: A one piece extrusion provides the base for a simple and effective vacuum tank for magnetic tape handlers. The extrusion carries longitudinal slots which accept stamped metal nuts. These nuts are readily positioned by sliding them along the slots. Slots along the edges of the extrusion are used to carry nuts holding hinges for a plastic cover over the tank front. Slots along the back and near the edges of the extrusion carry nuts for mounting the tank on the tape handler main frame. A longitudinal slot along the back of the extrusion and spaced in from one edge carries spring-loaded tubular inserts for attachment to the vacuum sensing tubes. Communication with the vacuum chamber is implemented by means of holes at appropriate places along the body of the extrusion.

Abstract: A programmable amplifier includes an operational amplifier receiving an analog input signal of a given polarity and voltage range and a read only memory (ROM) control which actuates six switches in a resistor configuration connected to the amplifier in such a manner as to provide a selection of two gain factors and direct or inverted polarity output in response to combinations of digital signals on two input lines to the ROM.

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: The vacuum for controlling tape loop tension in a magnetic tape handler is supplied by a low speed multiple stage vacuum blower and controlled by a low power solenoid and a flapper valve operated between two predetermined positions. In order to provide fast operation of the flapper valve in response to the low power solenoid a fast acting fluid amplifier is utilized between the solenoid and the flapper valve. The elimination of belts, gears and high speed blowers results in an unusually quiet system.

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: When a regulated power supply incorporating a series pass transistor as the regulating element is crow-barred, the control circuitry continues to drive the pass transistor to maximum available current. The pass transistor may be overheated and eventually both the pass transistor and the crow-bar itself may be damaged. To prevent this latter from happening, the drive to the pass transistor is cut back in response to the actuation of the crow-bar.

Abstract: A transistor circuit including a capacitor charging circuit and an actuator such as an electric motor provides a two part cyclic timing circuit, one part being one complete revolution of the motor and the other part being the charging time of the capacitor. The entire device is designed to run for an extended period on two dry cells. Practically no current is drawn while the motor is at rest contributing to a long battery life.

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: Chain or belt printers for high speed print-out from computers and the like employ metal or plastic type slugs clipped to a toothed elastomeric timing belt. The belt passes around two toothed pulleys one of which drives the belt so that the type slugs pass along a printing line at a predetermined speed. Pins holding and locating the slugs on the belt extend inside both top and bottom edges of the belt.The pulleys are constructed with peripheral slots to mate with the teeth on the inner surface of the timing belt and added teeth to support the belt at both of its outer edges and between the pins holding the slugs to the belt. This added support for the belt improves the printing accuracy under dynamic high speed printing operations.

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 the computer field tape handlers for magnetic tape are widely used. The magnetic tape is moved by a capstan driven by a high power low inertia motor since it is necessary to rapidly accelerate and decelerate the tape in both forward and reverse directions. A high power motor is provided with a command controlled direct current. The motor direction is determined by the selection of one of two pairs of solid state switches. Only one current control circuit is used. Transients are minimized by permitting only one pair of switches to be closed at any time and by switching when the controlled current is at a low value.