Abstract: A photoelectric smoke sensing chamber in a smoke sensing blind box which comprises a cylindrical body having inner and outer walls with vertical openings with both ends of the cylindrical body closed, the chamber being characterized by inner and outer walls fixed into an annular base and upwardly extended to the ceiling of the cylindrical body; a support for a luminous element and a light receiving element, which support is sealingly fitted into the inner edge of the annular base; light shading projections radially extended from at least one portion of the inner surface in full length of each of the inner and outer shell members; and a scattered light weakening layer formed at least on the inner surface of the cylindrical body for weakening scattered light occurring due to the reflection of the beam from the luminous element.

Abstract: A photoelectric smoke sensing chamber in a smoke sensing blind box which comprises a cylindrical body having inner and outer walls with vertical openings with both ends of the cylindrical body closed, the chamber being characterized by inner and outer walls fixed into an annular base and upwardly extended to the ceiling of the cylindrical body; a support for a luminous element and a light receiving element, which support is sealingly fitted into the inner edge of the annular base; light shading projections radially extended from at least one portion of the inner surface in full length of each of the inner and outer shell members; and a scattered light weakening layer formed at least on the inner surface of the cylindrical body for weakening scattered light occurring due to the reflection of the beam from the luminous element.

Abstract: A casing for electronic appliances is disclosed. The casing has an inner case having spaces defined therein by partitions, the spaces being adapted to receive various manipulation members, and an outer case adapted to be closely fitted to the outside of the inner case. In assembling, the outer case is fitted to the outside of the inner case, after placing respective manipulation members in respective spaces in the inner case, so that the manipulation parts are firmly clamped between the inner and outer cases of the casing.

Abstract: In a photoelectric synchronous smoke sensor of the type wherein an electric power consumption is reduced by sample-detecting the smoke while bringing both light-emitting section and light-receiving section in the actuated state in synchronism with each other, a photoelectric synchronous smoke sensor characterized in that said light-emitting section is actuated by a pulse of a narrow pulse width and said light-receiving section by a pulse of a wide pulse width, and an input signal is applied to a synchronism detector only within the time width of said pulse of a narrow pulse width in order to increase sensitivity, to stabilize performance and at the same time, to automatically supervise a power source voltage.

Abstract: A frequency synthesis method for an AM-SSB transmitter-receiver using a phase locked loop type synthesizer, having the steps of supplying a mixer with an offset frequency of an offset oscillator or a multiplied frequency thereof and an output frequency of a voltage-controlled oscillator, applying a difference signal outputted from the mixer to a variable frequency divider, and using a sum signal frequency outputted from the mixer as the local oscillation frequency of the receiver section and that of a mixer of the transmitter section where a transmitting frequency is produced.

Abstract: A transmission and reception control circuit for a transceiver adapted to compare the output frequency of a fixed frequency divider with that of a variable frequency divider thereby to automatically control the output frequency of a voltage-controlled oscillator, in which the output of a phase detector is compared with any of the output of a code converter, that of a channel-selection code generator and that of a press-to-talk switch singly or in combination thereby to control the operation of the transmitting and receiving stages.

Abstract: A channel selecting device having a channel setting generator for generating channel-number increasing or decreasing signals for channel selection, a logic system provided with a channel-code generating circuit for changing the channel code according to the number of channels and a digital-number generating circuit and a time constant circuit for suspending the operation of a clock-pulse generating section for a scanner during a predetermined time, the logic system performing the one-by-one shift or continuous shift of the channel number according to the duration of signals from the channel setting means, an indicator for indicating the channel number, and a jamming wave inhibiting means for suspending the operation of a transmission circuit when given signals from the channel setting means.

Abstract: A display device for use in a transceiver and the like having a display section which normally performs digital time display and, as occasion demands, performs channel display by the aid of a change-over switch.

Abstract: A tuning circuit suitable for use in a transmitter-receiver of the phase locked loop frequency synthesizing type which has two separate variable-capacity elements, one for the follow-up control of the phase locked loop and the other for shift and modulation, arranged in parallel with an inductor of an oscillation circuit and adapted to be energized by a DC power supply through a transmission-and-reception change-over switch.

Abstract: A phase locked loop type transmitter-receiver having a phase locked loop type synthesizer including a circuit in which a programmable counter, a phase discriminator, a low-pass filter, a voltage-controlled oscillator and a mixer are connected in a closed loop; wherein the mixer is connected to a reference oscillator connected to the phase discriminator through a fixed frequency divider, the mixer being adapted to mix frequencies fed from the reference oscillator and the voltage-controlled oscillator thereby synthesizing sum and difference signals thereof, the difference signal being fed to the programmable counter and the sum signal being fed to a transmitting-side mixer and a receiving-side mixer.

Abstract: A circuit for setting transmission and reception frequencies having a crystal-controlled oscillation circuit with a quartz oscillator, a plurality of capacitors different in capacity connected to the quartz oscillator, switching transistors connected to the capacitors respectively, and a change-over switch for selectively actuating the switching transistors.