Abstract: An electrically adjustable current divider means divides the output current of a constant current generator into a plurality of portions, a first of which is applied as tail current to a long-tailed-pair amplifier connection of transistors for controlling its voltage gain. At least one of the long-tailed-pair transistors has a resistive load; the quiescent value of the output voltage developed across this load has an undesirable tendency to exhibit shifts as gain is controlled. A second portion of divided output current from the constant current generator, exhibiting changes in magnitude complementary to those exhibited by the first portion, is applied to current-to-voltage converter means for developing voltage components to counteract the above-mentioned tendency towards shifts in the quiescent value of the output voltage as gain is controlled.

Abstract: Within a switching network of the type wherein at least one GTO device is rendered conductive or non-conductive to control the flow of current through a load, current is drawn from the gate of the GTO device and a shunt path is connected across the main conduction path of the GTO device simultaneously in response to a turn-off signal.

Abstract: A current flows between the collector and emitter electrodes of a transistor responsive to an operating potential being impressed between them, the emitter-base junction of the transistor being forward biased by leakage current flowing across its own collector-base junction. Increase of the current flow between the collector and emitter electrodes of the transistor beyond a desired level is precluded by sensing the current flow, applying the sensed current to a current-to-voltage converter, and applying the resultant voltage to the input of a threshold detector. The output circuit of the threshold detector shunts current away from the emitter-base junction of the transistor when the current flow between its collector and emitter electrodes tends to exceed its desired level thereby to cause the voltage applied to the input circuit of the threshold detector to exceed a predetermined threshold value.

Abstract: Within current scaling circuitry having bipolar transistors of the same conductivity type disposed in principal master and slave paths, the negative feedback current gain around the principal master path transistor is regulated in direct proportion with the level of a current source that is independent from both of the principal master and slave paths, to substantially achieve tracking between the level of the current source and the levels of current flow through the principal master and slave paths.

Abstract: A self-biased MOSFET with suitably biased substrate is used as one of the rectifiers in a rectifier circuit for converting a-c power to d-c power for application to a monolithic integrated circuit of which the rectifier circuit is a part. This avoids the parasitic transistor action which would accompany the use of an isolated pn semiconductor junction, which parasitic transistor action undesirably discharges a storage capacitor connected across the output of the rectifier circuit.

Abstract: A system utilizing the central vacuum system in the dental operatory to exhaust analgesic or anesthetic gas from a gas administration assembly. The system includes a nosepiece fitting over the nose of a patient, an exhaust assembly for removing exhaled gas from the nosepiece, and an exhaust chamber formed around the periphery of the nosepiece for scavenging gas leaking through the facial seal at the rim of the nosepiece.

Abstract: Regulated current sources of a type comprising first and second transistors of complementary conductivity types having respective input and output electrodes, the output electrode of each direct coupled to the input electrode of the other to complete a regenerative feedback loop tending to increase conduction in both transistors. The increased conduction of the second transistor is sensed by the input circuit of an amplifier exhibiting increasing gain for increased signal sensed by its input circuit. The output circuit of this amplifier is connected to the input electrode of the second transistor to complete a degenerative feedback loop which counteracts the regenerative feedback loop at prescribed current levels to establish the level of current regulation.

Abstract: A regenerative latch switch conducts responsive to a RESET pulse to selectively divert applied input current from the input circuit of a current amplifier such as a current mirror amplifier. Responsive to an ensuing SET pulse conduction of the regenerative latch switch is interrupted, so applied input current flows to the input circuit of the current amplifier for amplification.

Abstract: A scavenging mask apparatus for administering gas to a patient, the apparatus comprising a nasal cannula for delivering gas to the patient's nostrils, a tube connecting the cannula to a source of gas, a nosepiece adapted to fit over the nose and cannula, and a tube connecting the nosepiece to a source of vacuum. Gas exhaled through the patient's nostrils or escaping from the cannula is scavenged by the air flow in the nosepiece, thereby minimizing loss of gas to the environment. The nosepiece is also provided with a plurality of holes in the underside thereof to scavenge gas exhaled through the patient's mouth.

Abstract: Within a power supply circuit for a semiconductor laser, output current is maintained constant at each temperature level over an operating range and the magnitude of that constant current is varied directly with temperature to maintain the light output of the laser substantially constant over the operating temperature range. In the preferred embodiment, the negative temperature coefficient characteristic of the base-emitter junction voltage for bipolar transistors is utilized to compensate for the negative temperature coefficient characteristic of the light output from the semiconductor laser.

Abstract: A precision binary weighted current source comprising a switching network connected to a plurality of nominally equal current sources. The switching network has 2.sup.n inputs connected to 2.sup.n current sources, and has n+1 output currents with a precise binary relation therebetween. The switching network is organized internally as a plurality of two input commutating circuits arranged in a plurality of n ranks between the input terminals and the output terminals. Output terminals are selectively connected to each current source so that the average value of each output current is proportional to the average of all of the 2.sup.n input current sources.

Abstract: In a drive circuit having output current passing through at least one bipolar transistor, the rise and fall times of the output current are predetermined by controlling the rate of current change in the master path of a current mirror amplifier which has a separate slave path connected to supply base current for each bipolar transistor. The drain-source channel of an MOS transistor is connected to selectively supply current flow through the master path of the current mirror amplifier in one embodiment of the rate control means and the gate of the MOS transistor is connected in parallel with a capacitor to the output of a CMOS inverter to which control signals are applied.

Abstract: A current mirror receives as input current the leakage current through an auxiliary semiconductor pn junction, which leakage current emulates the leakage current of a similar semiconductor pn junction in a bipolar transistor used in the functional portion of the integrated circuit. The resulting output current of the current mirror is applied to counteract the effect of the leakage current.

Abstract: An improved circuit for measuring resistance, as for the resistance of a temperature sensor, wherein the resistance varies over a wide dynamic range. The circuit provides two switch means to charge two capacitors through the unknown resistance. A time interval means measures charging time for one or both capacitors. Since charging time is directly proportional to resistance, a value of resistance is computed for one or both charging times. Control means, responsive to the time interval means, is provided to sequentially operate one or both switch means, the control means including means for selecting that charging time which is as long as possible yet within the range of the time interval means, thereby obtaining a higher resolution measurement in the range of sensor resistance where resolution would otherwise be inadequate.

Abstract: An RC oscillator comprising an amplifier with a first RC voltage divider coupling its output circuit to its non-inverting input circuit and a second RC voltage divider coupling its non-inverting input circuit to its inverting input circuit. The first RC voltage divider comprises a series RC network in its series arm and parallel RC network in its shunt leg. The second RC voltage divider has a capacitor in its series arm and a resistor in its shunt leg.

Abstract: The current supplied by a constant current generator is selectively applied to the unilaterally conductive input circuit of a current amplifier and otherwise flows through other unilaterally conductive means. The current amplifier provides current flow through its output circuit only when current is applied to its input circuit.

Abstract: A current mirror amplifier in which the potentials appearing across the principal conduction paths of its master and slave transistors are maintained substantially the same. This is done by a differential-input, single-ended output amplifier, which is connected as a non-inverting amplifier in the direct-coupled feedback connection that conditions the master transistor to conduct applied input current via its principal conduction path.

Abstract: A three-terminal current amplifier has a current gain substantially independent of the forward current gains of its component transistors. It employs a first transistor with collector-to-base feedback regulating its collector current flow to equal applied input current and a second transistor having a base emitter circuit in parallel with that of the first transistor. Output current from the collector electrode of the second transistor consequently is proportional to the input current. Means are provided for maintaining the collector potentials of the first and second transistors substantially equal to help maintain a fixed relationship between the output and input current amplitudes.