Abstract: A CMOS current-mode folding amplifier circuit is provided that uses MOSFETs operating in relatively strong inversion. The CMOS current-mode folding amplifier circuit produces a saw-tooth shaped input-output characteristic which provides for relative precision in flash-type analog-to-digital converters. Furthermore, the CMOS current-mode folding amplifier circuit uses a plurality of simple current mirrors, in addition to biasing currents, for defining the switching levels. Accordingly, the current-mode amplifier requires less area on the chip and consumes less power relative to other analog preprocessing circuits. Moreover, the CMOS current-mode folding amplifier circuit is resilient to process, temperature and power supply variations. Tanner simulation tools using 0.35 ?m CMOS technology confirm the functionality of the current-mode folding amplifier.

Abstract: A current-mode analog computational circuit can be controlled to produce multiplying, squaring, divider and inverse functions and corresponding current outputs. The current-mode analog computational circuit is based on an implementation using MOSFETs operating in a sub-threshold region as can provide relatively ultra-low power dissipation. Furthermore, the current-mode analog computational circuit can be operated from a ±0.75 V DC supply. Tanner simulation results conducted using a 0.35-?m TSMC CMOS process confirmed the functionality of the multiplying, squaring, divider and inverse functions of the circuit. The current-mode analog computational circuit advantageously can have a total power consumption of 2.3 ?W, a total harmonic distortion is 1.1%, a maximum linearity error of 0.3% and a bandwidth of 2.3 MHz.

Abstract: Contamination monitoring of high voltage insulators provides a system and method producing an early predictor for high voltage insulator failure, allowing repairmen to either already be on site when a high voltage insulator fails in order to expedite repair time, or allowing repair and/or replacement of a faulty insulator before the failure actually occurs. The system and method provide transmission of an alarm signal when contaminant levels (such as equivalent salt deposit density (ESDD) levels) formed on a high voltage insulator exceed pre-selected threshold values, indicating the likelihood of high voltage insulator failure.

Abstract: The monitoring and early warning alarm system for high voltage insulator failure provides an early predictor for high voltage insulator failure, allowing repairmen to either already be on site when a high voltage insulator fails in order to expedite repair time, or allowing repair and/or replacement of a faulty insulator before the failure actually occurs. The monitoring and early warning alarm system includes a housing adapted for mounting on a high-voltage power line in proximity to a high voltage insulator associated therewith. A temperature sensor, a contamination sensor, a humidity sensor, or combinations thereof are mounted on the housing and the measured ambient temperature, pollutant contamination and humidity are compared with pre-selected threshold values of temperature, humidity and pollutant contamination.

Abstract: Contamination monitoring of high voltage insulators provides a system and method producing an early predictor for high voltage insulator failure, allowing repairmen to either already be on site when a high voltage insulator fails in order to expedite repair time, or allowing repair and/or replacement of a faulty insulator before the failure actually occurs. The system and method provide transmission of an alarm signal when contaminant levels (such as equivalent salt deposit density (ESDD) levels) formed on a high voltage insulator exceed pre-selected threshold values, indicating the likelihood of high voltage insulator failure.

Abstract: The system for monitoring a liquid level in an underground storage tank provides an external visual indication of a liquid level, such as water level, within a sealed underground storage tank. The system includes an ultrasonic transducer for generating regularly pulsed ultrasonic signals and for receiving reflected ultrasonic signals, which are reflected from a surface of the liquid stored in the underground storage tank. A pulser connected to a timer is in communication with the ultrasonic transducer for generating regularly pulsed ultrasonic signals. The timer is further used to measure the time period between generation of one of the pulsed ultrasonic signals and reception of the corresponding reflected ultrasonic wave. The height between the ultrasonic transducer and the liquid surface is then calculated based upon the measured time period. The liquid level is then displayed to the user on an external display.

Abstract: The high output impedance current source utilizes an opto-coupler integrated circuit to provide a high output impedance, regulated current to a load. The circuit includes an initial voltage source for energizing an LED. The light intensity of the LED is controlled by varying the voltage source or by a separate resistor. The LED selectively controls on-off gating of a phototransistor. The current supplied to an electrical load is a function of the light intensity produced by the LED, thus also being a function of the controlled initial voltage. The emitter of the phototransistor is connected to its base, thus making the output resistance of the current source very high and equal to that of a reverse-biased diode as long as the collector-to-base junction remains in the reverse-biased mode. The high output impedance current source can also be used as a voltage-to-current converter.