Abstract: Electronic circuitry monitors the electrical energy consumption of a system and displays the current cost of the energy usage. The projected monthly billing cost is calculated at the current rate of consumption, and an alarm signal is generated if the projected cost is higher than a budget amount. The current flow is sensed and digital pulses are fed to a microprocessor for counting and conversion to cost parameters. Clock pulses are also directed to the microprocessor for calculating the billing period and for displaying time parameters. A keyboard enables initializing and modifying the cost and time parameters in the microprocessor.

Abstract: A device for testing phase inversion of a circuit includes a signal generator having an assymetrically shaped positive phased test signal output electrically connected through a buffer circuit to the input of the circuit under test. A differentiator circuit electrically connected to the output of the test circuit, produces in response to the test circuit output, rectangular pulses whose amplitudes are proportional to the slopes of the test waveform. The differentiated output signals are isolated into positive and negative signals by a plurality of peak detectors whose outputs are fed to a summing amplifier. The summing amplifier amplifies the difference between the positive and negative isolated peak voltages and in turn drives a polarity indicating device which was previously calibrated to indicate a positive or negative polarity as either a phase or non-phase inversion. An alternate mode of measuring pulses directly and bypassing the differentiator is also provided.

Abstract: For monitoring the supervisory current in a communications line between a power source and a protected premises which forms a security protection circuit, monitoring apparatus utilizes sensitive solid state circuitry which appears transparent to the protection circuit. An operational amplifier input circuit protects the circuitry against component damage due to lightning, inherently rejects common mode errors due to noise, transients, and varying power supply voltage, and had an adjustable offset for line length compensation and circuit standardization. Voltage comparator circuitry indicates by digital signals the supervisory current level. After the operator conditions the apparatus for an abnormal current level which has been signalled, a lamp which blinks at a discernable rate is used to serve as a reminder of this state.

Abstract: A portable sensor adapted to be moved along a wall to indicate a change in the dielectric constant of the wall thereby to signal the presence of a wall stud within the wall. The sensor incorporates a capacitor plate positioned adjacent the surface in contact with the wall and a circuit for detecting any change in the capacitive charge on the capacitor. Any change in capacitive charge as the sensor is moved along the wall is due to a change in the dielectric constant of the wall because of the presence of a wall stud behind the wallboard. The sensor visually indicates any change in the dielectric constant in a manner to permit selection of the center of the change in dielectric constant thereby indicating the center of the wall stud. An additional feature of the circuit permits automatic calibration of the sensor to a level corresponding to the dielectric constant of the wallboard so that any change in the dielectric constant of the wall due to the presence of a stud is readily observable.