Several analog TV channels operate with stereo audio signals, but the vast majority of receivers are mono type. The adaptation of a mono television so that it applies two decoded audio signals to the inputs of a common stereo amplifier can be made from the circuit of the figure. This circuit must have its input connected to the output of the discriminator, and the reader must be aware of the need to remove the de-emphasis capacitor from this point of the circuit in order to let the pilot signal pass, without which decoding is impossible. The only adjustment of the circuit is made in the 22 k ohms trimpot so that there is the tuning of the pilot signal, which in the case of TV receivers has a horizontal scanning frequency and is therefore different from the signals used in common FM receivers. Short and direct connections for the passage of audio signals are essential for this circuit to work well.
