Abstract: A portable detection system (10) for hazardous materials including explosives and infectious or hazardous biological agents readily adapted to conventional mail collection boxes (12), rural mailboxes (100) and the like. The system includes a fan (14) and a sensor (16). The fan (14) provides sufficient airflow to circulate the air within a mailbox such that the internal air after coming in contact with the contents is directed the sensor for analysis. The air quality can be determined visually (137), audibly (138), or electronically (139). Consequently once such detection is made and the air is verified as being safe, the contents can be removed safely. If it is determined that the air contains some type of hazardous material, further steps can be taken to specifically locate the source of such hazardous material. An alternative embodiment includes a filter (15) to improve fan efficiency.

Abstract: A portable detection system (10) for hazardous materials including explosives and infectious or hazardous biological agents readily adapted to conventional mail collection boxes (12), rural mailboxes (100) and the like. The system includes a fan (14) and a sensor (16). The fan (14) provides sufficient airflow to circulate the air within a mailbox such that the internal air after coming in contact with the contents is directed the sensor for analysis. The air quality can be determined visually (137), audibly (138), or electronically (139). Consequently once such detection is made and the air is verified as being safe, the contents can be removed safely. If it is determined that the air contains some type of hazardous material, further steps can be taken to specifically locate the source of such hazardous material. An alternative embodiment includes a filter (15) to improve fan efficiency. The system is further adaptable to other mail container embodiments such as a mailbag (40).

Abstract: In a quadrature FM detector, demodulation is performed by a product detector which multiplies an amplitude limited FM modulated information signal by a version of the amplitude limited FM modulated information signal which has been phase shifted by a phase shifting network including a single tuned LC circuit. In order to assure that the LC circuit is tuned to the carrier frequency of the FM signal, the LC circuit is tuned by a variable impedance device in response to a control signal generated by a bus controlled DAC. The control signal is coupled to the variable impedance device at the same pin of an integrated circuit where the LC circuit is coupled to the demodulator.

Abstract: The present invention concerns a high impedance signal source driving a relatively low input impedance mechanical resonating device such as a ceramic filter having an input impedance which varies with frequency. The high impedance source is further loaded by a resonant circuit tuned to the center frequency of the mechanical resonating device. The skirts of the resonant tuned circuit decrease in impedance on both sides of the center frequency of interest substantially compensating for the change of circuit gain with frequency due to the change of input impedance with frequency of the ceramic filter.

Abstract: A wall display device, particularly suitable for displaying record albums including a plurality of blocks, one for each corner of the album having upper vertical corner channels to hold the bottom corners of the album and vertical side channels to hold the upper corners of the album where each block can support the corners of four different albums.