LF pre-amplifier circuit with two volume controls


Created on 06/14/1973 10:40 AM.

Updated 09.16.

Author: Radio Magazine.

A feature of the LF preamplifier according to the circuit shown in Fig. 1, is the presence of two volume controls. Potentiometer R1 sets the signal level on the base of the first stage transistor T1, at which distortions arising from the amplifier overload are excluded.

The second potentiometer R8 is used to adjust the volume of sound playback while listening to programs.

This complication of the amplifier makes it possible to carry out smooth volume control over a wide range when operating from almost any input signal source.

The tone control is made according to the usual scheme, with separate regulation for the lower and higher frequencies using potentiometers, R10 and R13, respectively.

The amplifier can use domestic transistors of the KTZ12 series. Potentiometers must have an inverse characteristic (type B).

Source: Radio, 1973, No. 6, p. 58.

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