Transistor rauschunterdrueckungsschaltung either, which consists of at least two-stage noise amplifier, a connected rectifier and a downstream the rectifier switching transistor is

摘要

1,038,450. Muting; interference suppression in radio receivers. TESLA, NARODNI PODNIK. May 11, 1965 [May 16, 1964], No. 19819/65. Headings H3T and H4L. In a muting arrangement operated by noise, the audio signal is applied to a two-stage transistor amplifier T 1 , T 2 , the resistance/capacitance elements of which are so chosen that its output predominantly comprises noise. This is fed to a diode rectifier D which biases back a transistor T 3 in the emitter circuit of transistor T 4 , which is in the audio circuit of the receiver and so cuts off its current. According to the invention the second transistor T 2 is an emitter follower, being directcoupled to the first, and feeds diode D over capacitor C 3 . A delay bias is applied to diode D from resistors R 6 , R 7 and adjustable potentiometer R 8 in the H.T. supply.