Abstract: A method and apparatus for monitoring stack gas emissions wherein a probe including temperature and pressure indicating transducers is sequentially located at predetermined positions within a smokestack and the output of such transducers is fed into an electronic data logger for retention therein. The data logger includes a light hand held module having a liquid crystal display and start/reverse/advance pushbutton switches whereby the data logger can be remotely controlled. The invention eliminates the necessity of using two operators to record the desired information and significantly reduces the cost of producing accurate evaluation of stack gas emissions.

Abstract: A microcontroller is provided having an on-chip electrically erasable programmable read-only-memory (EEPROM), which is user programmable via a programming register. The microcontroller includes a low voltage program inhibit (LVPI) circuit which is combined with the existing EEPROM design. By integrating the LVPI circuit into the EEPROM, the EEPROM may be protected without disabling the entire data processing system. If the supply voltage (V.sub.DD) falls below a predetermined voltage level, the LVPI circuit inhibits the use of the EEPROM programming register, thereby preventing the CPU from programming or erasing the EEPROM. A comparator in the LVPI circuit compares a precision reference voltage to a voltage divided off of the power supply (V.sub.DD), and provides a output signal to the EEPROM programming register. During normal operation, the comparator output signal is a logic low, which enables the user to program or erase the EEPROM, via the programming register.

Abstract: A trap for mice or other small animals has an open-topped box-like base to which are hinged a striker and a combined bait holder and retainer, an elastic band tensioned between the striker and base urging the striker down from a raised or set position to striking position, entering the base, the retainer being releasably engageable with the striker to hold it in set position until the bait holder is depressed to free the striker to be driven to striking position, the base, the striker and the bait holder and retainer being assembled from a single blank of sheet material, the striker and the bait holder and retainer being hinged to the base along bend lines in this material.

Abstract: An input signal is mixed with a reference frequency and with a frequency 90.degree. phase-displaced from the reference frequency, so as to produce resultant waveforms whose slopes are dependent on the respective frequency differences detected. Both waveforms are differentiated to produce respective slope signals. Two comparisons are then carried out: one comparison compares the sign of one slope signal with the sign of the waveform producing the other slope signal, and the second comparison compares the sign of the other slope signal with the sign of the waveform producing the first slope signal. The two comparisons produce nominally identical intermediate signals having values dependent on the difference between the input and reference frequencies. Control means operative in dependence on the relative magnitudes of the two waveforms then selects the intermediate signals alternately, each selected intermediate signal constituting the output signal of the circuit.