Abstract: An apparatus connectable between a current source and an electrical load for indicating current flow through the load above a threshold level. The indicator includes two negative temperature coefficient (NTC) thermistors, and a neon indicator lamp. The first thermistor is connected directly in series with the electrical load and the second thermistor is connected in series with the neon lamp. The thermistors are packaged together by an epoxy resin, which thermally couples the thermistors so that both thermistors operate at substantially identical temperatures. Current flow above the load's operational threshold level causes the first thermistor to heat to an equilibrium temperature well above the ambient temperature. At this elevated equilibrium temperature, both resistors have extremely low resistance values. The low resistance value of the second thermistor permits maximum current flow to the neon lamp, which illuminates the lamp.

Abstract: A sensor probe and sensor detection circuit used in an electronic temperature control circuit for preventing the control circuit from driving an external device such as a heater when the sensor probe has been disconnected from the control circuit. The sensor probe includes an NTC thermistor and a limiting resistor that are connected in parallel and potted in epoxy. The thermistor and limiting resistor of the sensor probe form part of a lower leg of a voltage divider in the control circuit. The sensor detection circuit compares the voltage signal generated by the sensor voltage divider to a predetermined threshold or ceiling voltage value. During normal operation, when the sensor probe is attached to the control circuit, the resistance of the sensor probe insures that the voltage signal from the sensor voltage divider remains within a predetermined voltage range and does not exceed the predetermined ceiling voltage value.

Abstract: An attachment used with a sensor, which includes an exposed sensing element, for preventing birds and animals from perching over the sensing element is disclosed. The attachment includes an elongated bent rod and a mechanism for mounting the rod to one of the side walls of the sensors. When mounted to the sensor's side walls, the bent configuration of the rod defines an open area adjacent the sensing element, which is exposed from an end wall of the sensor. The rod's distal end segment extends longitudinally over and is spaced from the sensing element, while the other segments of the rod are spaced laterally and diagonally from the sensing element. The distal end segment is spaced above the top of the device at a specific height to prevent interference with the operation of the device while preventing birds and animals from moving between the distal end segment and the sensing element. In addition, the laterally extending segments of the rod are inclined to prevent birds and animals from perching on them.

Abstract: A power circuit for a precipitator utilizes a pair of silicon controlled rectifiers (SCR's) which are triggered by detecting the zero crossover of a power signal. The power transmitted through the SCR's is determined by the time period from the detection of the zero crossover to the generation of the trigger signal. Power signals are typically subject to noise which interferes with the detection of the zero crossover. Filters are provided for reducing the noise interference but function without altering the phase relation of the zero crossover of the filtered signal in respect to the unfiltered power signal. A pulse train of higher frequency than the power signal is generated to provide a plurality of triggering pulses for the SCR. Further, phase control signals are generated for each SCR to prevent the generation of trigger pulses when the SCR's are reverse biased.

Abstract: An active voltage divider providing output voltage overload protection operably effective in the event failure of the primary resistor should occur. Comprising the divider circuit is a differential amplifier operable as an integrator, a first pair of grounded diodes providing primary over-voltage protection for a first summing junction of the amplifier and a second pair of grounded diodes providing voltage backup protection for a second summing junction of the amplifier.

Abstract: A data acquisition unit accepts serial bit streams from a control device for a vending machine, and it records the data represented by those serial bit streams. The data in one of those serial bit streams will include the number of vends of each product corresponding to the various selection switches of the vending machine, and the data in the other of those serial bit streams will include the price data. The data acquisition unit will store the price data in a non-resettable location and also in a resettable location. A readout can be actuated to effect the displaying of the selection line number and of the corresponding settable and non-resettable price data.

Abstract: A bill-handling device provides relative movement between a sensor and a U.S. bill or other object to permit that sensor to sense longitudinally-spaced areas on that U.S. bill or other object which correspond to areas, on authentic U.S. bills or counterfeits thereof, where significant data is found. Data which is obtained during the sensing of those areas is stored, and subsequently is analyzed to determine the authenticity and denomination of the U.S. bill--if it is one of a plurality of bills of specifically-different denominations.

Abstract: A piece of scrip is engraved or printed with groups of patterns which can be sensed by a validator for scrip and one of those groups of patterns will define a code which will permit that piece of scrip to be accepted only by a scrip validator or by scrip validators which have that same code stored therein. Two additional groups of patterns define codes which can cause that scrip validator or those scrip validators to automatically respond to the codes stored therein to actuate price-determining relays within a vending machine. Each pattern is formed by a number of spaced parallel lines, and the various patterns on a piece of scrip can be given different identities merely by changing the spacing between the trailing edges of those spaced parallel lines. The patterns in each group of patterns will be sensed in a prescribed sequence, and the sequentially-sensed patterns in any of those groups of patterns can be given various identities.

Abstract: A method and apparatus for maintaining quality control in a friction welding operation where two workpieces are relatively rotated while being constantly pressed into engagement at a common interface. One or more operating conditions, including axial upset at the common interface, are monitored and a signal is substantially instantaneously produced to indicate correlation between the monitored operating conditions and respective ranges for those conditions which are predetermined as being representative of an effective bond between the workpieces. In a first embodiment, operating conditions of axial upset, pressure of engagement between the workpieces and relative rotating speed are simultaneously monitored. In a second embodiment, axial upset is monitored in selectively delayed relation to commencement of the weld in order to provide improved quality control over inertia welding.

Abstract: A device for controlling the rotational speed of a friction welder as a function of the combined length of the pair of parts to be welded, within predetermined tolerances, so as to produce welded pieces of uniform length in spite of minor variations in the lengths of the parts. Logic and sequencing circuitry specially adapted to carry out this function at minimum cost is also described.

Abstract: A piece of scrip is engraved or printed with groups of patterns which can be sensed by a validator for scrip and one of those groups of patterns will define a code which will permit that piece of scrip to be accepted only by a scrip validator or by scrip validators which have that same code stored therein. Two additional groups of patterns define codes which can cause that scrip validator or those scrip validators to automatically respond to the codes stored therein to actuate price-determining relays within a vending machine. Each pattern is formed by a number of spaced parallel lines, and the various patterns on a piece of scrip can be given different identities merely by changing the spacing between the trailing edges of those spaced parallel lines. The patterns in each group of patterns will be sensed in a prescribed sequence, and the sequentially sensed patterns in any of those groups of patterns can be given various identities.