Abstract: A system for monitoring corrosion in metal by comparing a test sample exposed to a corrosion causing environment and a reference sample exposed to a protected environment. An AC voltage source generates a square wave signal oscillating between ground and voltage Vcc and a filter is positioned to filter the signal to produce a sine wave with no second harmonic component. A voltage-driven current source and inverting amplifier produce a current referenced to 0.5 Vcc to provide an AC current from the drive voltage driven sinusoidally and symmetrically above and below 0.5 Vcc. A transformer steps up the AC current and thereafter transmits the current through the samples to an amplifier for amplifying the current to provide outputs in a ratio representing the degree of corrosion of the reference sample. The system can operate in situ for on site measurement and uses relatively low current to permit long operation.

Abstract: A system for maintaining constant pressure, such as at a mosquito fogging nozzle, by electronically controlling the speed of an engine that is coupled to a blower. A pressure sensor measures the pressure provided by the blower and provides a pressure signal to the electronic engine controller. The engine controller is of the proportional-integral (PI) type and utilizes pulse-width modulation (PWM) techniques to control an electromechanical actuator attached to the throttle of the engine to vary the engine speed. Constant pressure is maintained despite changes in the ambient temperature, humidity and barometric pressure. A safety circuit prevents engine over-speed if the pressure signal is lost. An over-speed circuit monitors and controls the engine speed at higher RPMs.

Abstract: A micropower apparatus and method for milliohm resistance detection includes a drive circuit and a monitoring circuit. The drive circuit includes a step up current transformer that is driven by a square wave oscillator via a low pass filter and voltage-driven current source. The drive circuit drives a series arranged test coupon and reference coupon, the latter being exposed to the elements. The coupons are Kelvin connected to the monitoring circuit, which includes a pair of low noise, low offset pre-amplifiers, a pair of post amplifiers connected to outputs of the pair of pre-amplifiers, a pair of full wave rectifiers connected to outputs of the pair of post amplifiers, and a pair of low pass filters connected to the outputs of the pair of full-wave rectifiers. Resistance values of the test and reference coupons can accordingly be monitored ratiometrically to determine a state of a selected environment by, for example, detecting changes in electrical resistance due to corrosion of the test coupon.

Abstract: A micropower apparatus and method for milliohm resistance detection includes a drive circuit and a monitoring circuit. The drive circuit includes a step up current transformer that is driven by a square wave oscillator via a low pass filter and voltage-driven current source. The drive circuit drives a series arranged test coupon and reference coupon, the latter being exposed to the elements. The coupons are Kelvin connected to the monitoring circuit, which includes a pair of low noise, low offset pre-amplifiers, a pair of post amplifiers connected to outputs of the pair of pre-amplifiers, a pair of full wave rectifiers connected to outputs of the pair of post amplifiers, and a pair of low pass filters connected to the outputs of the pair of full-wave rectifiers. Resistance values of the test and reference coupons can accordingly be monitored ratiometrically to determine a state of a selected environment by, for example, detecting changes in electrical resistance due to corrosion of the test coupon.

Abstract: A system for maintaining constant pressure, such as at a mosquito fogging nozzle, by electronically controlling the speed of an engine that is coupled to a blower. A pressure sensor measures the pressure provided by the blower and provides a pressure signal to the electronic engine controller. The engine controller is of the proportional-integral (PI) type and utilizes pulse-width modulation (PWM) techniques to control an electromechanical actuator attached to the throttle of the engine to vary the engine speed. Constant pressure is maintained despite changes in the ambient temperature, humidity and barometric pressure. A safety circuit prevents engine over-speed if the pressure signal is lost. An over-speed circuit monitors and controls the engine speed at higher RPMs.

Abstract: A driver that provides voltage level and polarity select control via a signal to an electrochromic device to vary light transmittance of the device. The driver has a fail-safe feature relative to the electrochromic device if a microcontroller of the driver fails. The driver is sufficiently efficient so as not to necessarily need a heat sink. The driver may sense and measure current and voltage into the electrochromic device.

Abstract: A transmitivity sensor having a light source and a detector on one side of a medium with a reflector on the other side of the medium so as to reflect the light from the light source back through the medium to the detector. For instance, the sensor may be used on a window of a sealed building or container without having connections to the source and detector break the integrity of the window seal relative to the building or the container. The magnitude of the light signal on the detector relative to that of the source is an indication of the transmitivity of the window. Electronics to effectively implement the sensor are connected to the source and detector. The electronics may contain, for example, a source driver, a detector amplifier, a band-pass filter, a logarithmic amplifier and various voltage sources. Other items may be a part of the electronics as desired.

Abstract: A solid state power supply circuit for providing high frequency power to ignite oil or gas and operate neon sign transformers. A switch operates in conjunction with a resonant tank circuit to supply power to the resonant tank at a predetermined time. The timing of the pulse is controlled to occur when the operation of the transistor will result in providing maximum energy to the load while minimizing power dissipation in the transistor. An amplifier and clamping circuit also operate to limit the duration of the pulse to further reduce power dissipation in the switch.

Abstract: A device for transferring electrical power from a stationary member to a rotatable member is provided by incorporating an air core transformer of which a first coil is rigidly attached to the stationary member and a second coil is rigidly attached to the rotatable member. A power converter is provided to convert input power from a first frequency to a second frequency. The first frequency can be that of a wall service within a family residence and the second frequency can be approximately 30 thousand hertz. The second frequency is provided to the electrical conductor of a first coil. The first and second coil of an air core transformer are used to transfer power across an air gap to the second coil. The transferred electrical power is then rectified to provide DC power to a plurality of electrical components that are rigidly attached to the rotatable member.

Abstract: A force sensor is provided which incorporates a piezoceramic element between first and second members that are moveable relative to each. The piezoceramic element is disposed within a cavity that is formed in the first member. The cavity extends between an opening and a wall within the first member. A second member is disposed within the cavity and slideably associated therewith. A spring is provided to permit the piezoceramic element to be preloaded without damaging it. First and second conductive elements are disposed on opposite sides of the piezoceramic element to facilitate electrical connection between the piezoceramic element and an external device.

Abstract: A plurality of fluid condition sensors are combined together to provide a sensor cluster that senses turbidity, temperature, conductivity and the movement of a ferromagnetic object. The plurality of sensors are attached to a substrate and encapsulated, by an overmolding process, with a light transmissive and fluid impermeable material. The sensor cluster can be disposed at numerous different locations within a body of fluid and does not require a conduit to direct the fluid to a particular location proximate the sensor. In a preferred embodiment of the present invention, a circuit is provided which monitors the signal strength of first and second light sensitive components to determine turbidity and, in addition, those signal strengths are also used to advantageously determine the most efficient magnitude of current necessary to drive a light source, such as a light emitting diode.

Abstract: An optical system made up of vertically stacked omnidirectional modules, each having apposed reflectors, one being conical and the other being paraboloidal, and the modules being vertically spaced along an axis so that generally horizontal light from any direction is reflected by the surface in a desired sequence to a light responsive device.

Abstract: A digital data modem arrangement is disclosed for use in a multi-drop communication system using either telephone lines or a pair of conductors. The communications device connected to a communications channel is readily adapted to a voice grade telephone line or a pair of continuous conductors. The disclosed digital data modem is capable of operating with either type of communications channel without the need of bridging amplifiers, and without substantially loading the impedance of the communications channel.

Abstract: A gated pulse generator produces on output pulse for every period in which an input signal is continuously in a particular state for longer than a minimum gating interval. If the input signal changes state within the minimum gating interval, no output pulse is produced.

Abstract: A sine-to-square wave converter circuit utilizes a programmable unijunction transistor (PUT).

Abstract: An interval timer for use in traffic control, industrial process control, or other interval timing applications includes a gated pulse generator.