GB1260433A - Indicating instrument - Google Patents

Abstract

1,260,433. Tuning indicators. ERNST & WILHELM BERTRAM. 20 Nov., 1969 [20 Nov., 1968], No. 56918/69. Heading H3Q. [Also in Division G1] An indicating instrument 1 for use in radio apparatus to assist in tuning the apparatus to maximum signal strength at selected frequencies has (i) a pointer 2 which is adapted to move, during tuning, in one direction with increasing signal strength and in the opposite direction with decreasing signal strength and (ii) a pointer 6 which moves with the pointer 2 in the first direction but remains substantially stationary upon at least initial movement of the pointer 2 in the opposite direction so that the pointer 6 can indicate the position of the pointer 2 which represents maximum signal strength. Lost motion mechanism 7 interconnects the two pointers so that when the pointer 2 moves with a decrease of signal strength the pointer 6 follows after an initial movement B, large enough to be readily observed but small enough to embrace signals from, but a single station. The mechanism 7 may take the form of a U- shaped element attached to one of the pointers and embracing the other or of a stop on each pointer for engaging the other, Figs. 10, 11, 12 (not shown), or of a pin-and-slot as shown in Fig. 13. In each case the two pointers overlap when moving with increasing signal strength. A moving-coil instrument is inserted in the circuit of a radio receiver so that when a tuning Knob is turned to bring the receiver into the sphere of influence of a given transmitter the instrument pointer 2 will move over a scale 3 followed by the pointer 6 until a maximum value has been passed, signalled by the pointer 2 moving down scale leaving the pointer 6 indicating the maximum, whereupon the tuning knob is turned back until the pointer 2 returns to the maximum. The pointer 6 is attached to an axle 10 whose pointed ends rotate in bearings in parallel arms of a support, means being provided for adjusting the friction. Part of the axle 10 may be surrounded by a chamber containing silicon grease to provide damping. The pointer 6 and its support are formed as a unit for attachment to the moving-coil instrument and their combination (including a scale) form a unit for attachment to the radio set. The pointers and coil are fully balanced. The pointers 2, 6; mechanism 7; support structures and housing may be made of plastics material. The support for the pointer 6 may be fastened to the instrument housing by screwing, pegging or adhesive or by snapping resilient parts into engagement.