Detection control circuit

The detection signal of this circuit is generated by white noise passing through a 0.2Hz comb filter and a lOkHz low-pass filter,
with an interval of 0.2,Hz and equal peaks. The waveform is shown in Figure 9, 23 0. If the circuit does not use a single-chip computer control system,
the function of the automatic noise sequence generator in the chip can be realized through the standard logic circuit shown in Figure 9-24. Only part of it
is used by CD4060. It consists of a clock and a two-bit binary counter. CD4556 is used to drive
the LED display detection sequence port
    SSM-2125/2126 using a positive logic control system. When the voltage is greater than 2.4V, it is considered "high", and when the voltage is less than
0.8V, it is "low". The working state of the circuit is set by controlling the arrangement and combination of the control signals of the terminals DMl-DIVh
to realize the switching of Dolby four-channel (directional logic), Dolby three-channel, two-channel stereo and automatic balance circuit,
noise generation, Mute and other functions. a"¨CMz terminal is used to control the four working modes of the center channel: Normal, Wide
, Phantom, and Off. In normal mode, the low-frequency response of the center channel is limited
to 100Hz. You can use Small size center speaker; in wide mode, the center channel outputs a full-band signal; in phantom mode,
the center speaker does not need to be used, and the center channel signal is evenly distributed to the left and right channels.
    This circuit should also be integrated Pin 30 of the circuit is the surround output termination delay, as well as auxiliary
circuits such as filtering, noise reduction and volume control to enhance the surround sound effect.
    SSM-2125/2126 is a high-performance Dolby directional logic decoder that has always been Tianlong Company, which pays attention to sound quality, uses
it to produce AV power amplifiers. The application of this circuit is still rare in China.