GB474266A - Improvements in rectifier systems for television purposes - Google Patents

Abstract

474,266. Television; valve detecting circuits. RADIOAKT.-GES. D. S. LOEWE. July 10, 1936, No. 19198. Convention date, July 11, 1935. [Classes 40 (iii) and 40 (v)] A television detector directly coupled to a following amplifier has a characteristic such that the output increases more rapidly than the input to compensate for decreasing eye sensitivity. Fig. 2 shows an anode bend detector 3 directly coupled to an output amplifier 7, a resistance condenser combination 9, 10 being provided to accentuate high frequencies. The carrier frequency is prevented from affecting the cathode-ray tube 8 by compensating condenser 11 connected to points of opposite phase. In a modification, Fig. 2a (not shown), the condenser is used in the detector anode circuit instead of the circuit of the output valve, alternatively, a push-pull detector, Fig. 2b (not shown), may be used which achieves the same object and does not impose a capacitive load on the circuit. The synchronizing impulses are preferably taken off before the output stage 7 by an amplitude filter 14 and transformers 15, 16. The grid of the output valve is biassed positively so that' it is operative only on image signals while the same bias applied to the amplitude filter renders this inoperative except on synchronizing signals. Fig. 3 shows an arrangement in which anode voltage for the detector 3 and for biassing the output stage 7 and the amplitude filter 14 are obtained from the voltage across series resistance 21. Fig. 4 shows a pentode detector, a diode in the envelope serving as the amplitude filter in which overmodulation is prevented by limiting the anode potential. The Specification as open to inspection under Sect. 91 also describes an arrangement, Fig. 5 (Cancelled, not shown), in which the output amplifier is dispensed with and an amplitude limiter diode and a full wave diode rectifier directly feeding the cathode-ray tube are contained in a common envelope. This subjectmatter does not appear in the Specification as accepted.