Patent GB-531187-A (GB)
Title: Control systems for radio receivers or other electric wave apparatus
IPC: H03J5/14
Filed: 1939-06-29
Abstract: 531,187. Electric control systems. PHILCO RADIO & TELEVISION CORPORATION. June 29, 1939, No. 18960. Convention date, July 20, 1938. [Class 40 (i)] [Also in Group XXXIX] A control system for a wireless receiver or other electric wave apparatus utilizes impulses one of which has controllable duration whereas the others are of fixed duration. The invention is desscribed in connection with distant inductive control of a wireless receiver in which certain impulse trains which include a long impulse of variable duration control a motor to drive the volume control in accordance with the duration of the impulse.and other regular impulse trains select tuning positions to which the tuner of the receiver is driven bv the motor. The transmitter, Fig. 2, comprises a tuned oscillator 13 keyed by a dial impulse transmitter 11 of ordinary type except that the finger plate has a projection 21 engagable by a press button 22 to prolong the last impulse (make) for any desired period. The filament circuit of the valve is made at contacts 18 when the dial is offnormal. The signals are transmitted inductively by means of coil 17. The receiver, Fig. 7, comprises coil 6, amplifying and rectifying valves 44, 46, 50, 61 which actuate the stepping magnet 69 of a switch 66, 67 which in its earlier positions controls increase or decrease of volume in accordance with the duration of a final impulse, and in its later positions marks contacts associated with a motor-driven tuning-control device of the gapped segment type. The tuning condenser 108, combined volume control potentiometer 40 and on-off switch 38, and muting contacts 112 are indicated in the small dotted rectangle. The power supply for the control system is connected up over a two-way switch 39 which if in the right-hand position, is effective only if the receiver switch 38 is on, but if 39 is in the left-hand position, the control system is energized independently of the receiver switch which may then be remotely controlled. The impulses which may be of 400 kc. are amplified at 44, 46 and rectified by valve 50 which is direct coupled to a further amplifier 60 having the stepping magnet in its anode circuit. Volume control increase or decrease is effected by sending two or three impulses, the last of which is prolonged in accordance with the volume desired. The first contact of wiper 70 is left blank for a purpose described later but this wiper, over contacts 2 and 3, energizes a circuit for motor 91 to drive the volume control potentiometer in one direction or the other, the on-off switch 38 being operated in one extreme position. In the first 3 positions of wiper 71, the prohibitive bias on valve 82 is removed and release magnet 75 in its anode circuit is operated but is not effective until the stepping magnet is released on termination of the prolonged impulse. The time constant of the grid circuit of valve 82 is such that the prohibitive bias is not removed during 3 short impulses, bias being obtained from the negative lead of the centre-point-grounded supply transformer secondary 27. In the case where energization of the control circuits is dependent on the receiver switch 38, the release arrangements function due to the charge on the smoothing condensers after switch 38 is open. Timing control. In response to 4 to 10 impulses, wiper 70 energizes the motor 91 over contacts such as 4c and wiper 71 energizes a clutch magnet 105 which gears the motor shaft to the tuning control shaft 107. The bias control circuit of valve 82 now passes over closed off-normal contacts 87 of the stepping switch and contacts 89 opened when the motor is running so that prohibitive bias is not removed until sometime after the motor is stopped whereupon the stepping switch is released. Minimizing the effects of disturbing impulses. The control signal receiving arrangements in addition to the sharply tuned signal frequency circuits are protected from operation by interfering impulses by (1) a filter 62, 65 having a time constant such that high pulse frequencies are attenuated (2) a blank first contact of the stepping switch which renders isolated single impulses ineffective (3) the feature that the prohibitive bias on the release control valve 82 is removed on long impulses and (4) condenser 121 at the power plug which is in addition to the usual filter at the receiver power supply equipment 35. Specification 531,190, [Group XXXIX], is referred to.