Abstract: An intercom system for mansion/apartment house of the present invention can achieve the power saving by suppressing a current consumption at the time of calling by a visitor standing at a main entrance or a residential front door or at the time of locking or releasing an electric door lock which is mounted on a front door of the main entrance and can ensure the favorable talk quality by suppressing howling. To a common bus, at least one main entrance station including a talk module for performing calling and talking and at least one switch module being connected to the talk module and having a call switch for performing selecting of a station, a bus controller for supplying a power to a common bus, and a plurality of residential master stations for performing calling and talking with the main entrance station are connected in parallel respectively.

Abstract: A method for detecting deterioration of solder paste printing includes defining a check pattern region on a portion of the printed circuit board PC separated from the electrical circuit, forming fine pitch check through-holes 8a in the metal mask 7 with a pitch finer than that of the electrical circuit within a region of the metal mask corresponding to the check pattern region, printing solder paste 9 onto the check pattern region through the fine pitch check through-holes of the metal mask, monitoring for defects in the printed check pattern and detecting a defect in the check pattern region before the solder paste printing onto the electrical circuit has deteriorated. The method enables maintenance of the best condition of the solder paste printing onto the electrical circuit.

Abstract: A telephone transmitter in which a cavity is formed in front of a vibrating membrane of the microphone transmitter to thereby reduce wind-noise. The cross-sectional area and volume of the cavity are larger respectively than the cumulative total cross-sectional area and volume of the apertures formed in the mouthpiece of the telephone transmitter. At least one of the apertures may be formed to serve a shielding function to prevent an air stream from directly blowing onto the vibrating membrane, thereby further reducing wind-noise pickup by the transmitter.

Abstract: In a time division multiplex network the channel assignment is controlled by assigning each channel, in a channel-by-channel sequence, to each subscriber pair that are communicating or wish to communicate. The subscriber address-data for the addressee and the addressor of each so-assigned channel are stored, respectively, in corresponding address locations of a transmission side circulating read/write memory and a receiving side circulating read/write memory. A reset word is stored in either the receiving side or the transmission side memory in a memory location following the last memory location containing subscriber address-data. The corresponding memory locations on the transmitting and receiving sides are read out in response to counter outputs and the subscriber address-data of each so-assigned channel are used to provide synchronous gating pulses to the respective modulation/demodulation units of the addressee and the addressor of each channel to establish communication therebetween.

Abstract: In a time division multiplex network the channel assignment is controlled by assigning each channel, in a channel-by-channel sequence, to each subscriber pair that are communicating or wish to communicate. The subscriber address-data of the addressee or the addressor of each so-assigned channel is stored in a circulating read/write memory with a reset word stored in a memory location following the last memory location containing subscriber address-data. The memory locations are addressed in a successive manner in response to an incrementing clock count and the subscriber address-data, as they are read out from the successively addressed memory locations, are used to provide gating pulses to the respective subscriber modulator/demodulators, and the reset word, when it is read out, resets the memory to repeat the memory read-out cycle.