LC172, LC171 audio voltage controlled lighting control special integrated circuit

The audio voltage-controlled lantern circuit made with the LC172 integrated circuit is shown in Figure 2-114. If the LC171 integrated circuit is used,
since it has only three outputs, the A output should be omitted, that is, the peripheral components of pins 11 and 12 should be omitted. .
    VDI~VD5, R3 and C9 form a rectification and voltage stabilizing circuit, which outputs 12V DC power for the integrated block. VD6 is
an external rectifier tube for voltage-controlled audio signals. The audio signal from the audio equipment is sent to the 8th pin of the integrated block through Cl and Rl. By adjusting
the resistance of Rl, the gain of the audio amplifier AF inside the integrated block can be controlled. When R1=20~50k 0, the corresponding gain is
35~ 20dB. (If the input audio signal is strong (greater than 1V), you do not need to use the amplifier in the integrated block. You can
directly send the audio signal to the 10th pin of the integrated block. At this time, the 8th and 9th pins are left floating. ).
The audio signal amplified by the integrated block 's internal amplifier AF is output from pin 9 and coupled to the IO pin via C2. VD6
rectifies this audio signal and turns it into a DC voltage-controlled signal to control the integrated block's internal voltage-controlled oscillator. The oscillation frequency of vco. This controls
the cycle rate at which the four output terminals output high levels. Therefore, the cyclic flashing of the colored lamp HINH4 is controlled by the strength of the audio signal.
    C5-C8 are to prevent radio frequency radiation interference
, and the capacity can be selected from 0+01 to 0.033 uF.
If there is no requirement to prevent radio frequency radiation interference, these four capacitors
can be omitted. C3 is the anti-vibration capacitor of the audio amplifier.
If the built-in amplifier of the integrated block is not used, this capacitor can
be omitted. The modulation characteristics
    of the output cycle frequency of this circuit LC172
are shown in Figure 2-115. It can be seen from the figure that
when the input audio signal is stronger, the flashing cycle frequency
f (AB, c, D) of the colored lights will be higher.