Delay light circuit using music integrated circuit

It is a delay spider using KD-9300 music integrated circuit. When the key switch SB is pressed, the light
E will light up. After a delay of about 20s, the light E will automatically turn off.
    VD, vs,C. , (, etc.
form a simple capacitor drop Jl, half-wave
rectification and voltage stabilizing circuit, and output about 3V
DC voltage for the KD-9300 Zhoule
integrated circuit. Normally, the music
integrated circuit is very static, and
the output terminal is O /'P has no signal output, the
diode VT1 is cut off, the thyristor
VTIi is turned off, and the light F is small.
When you need to turn off the light, press SB. The trigger
terminal TRI of the music integrated circuit is triggered by a high level, and the O/P terminal is output The internally stored Lezhan signal is smoothed by C to make VT1 conductive. At this time, current flows through R into the f] pole of the thyristor VTH, causing VTH to rise and pass , and the lamp F is energized and glows. After the tone is played, VT1 returns to the cut-off state, VTH loses the trigger current and cuts off when the AC crosses zero, and the light goes out. The music integrated circuit uses KD 9300, HFC-9300, etc. The delay time of the circuit is mainly stored in the     music integrated circuit. It is related to the length of the music signal, so be careful to choose one with a stronger music tone, usually about 20s . There is an external oscillation resistor on the soldering piece of the music integrated circuit , usually 68kfl, and its resistance determines the internal storage The reading speed of the music signal , increasing the resistance value can extend the delay time of the circuit.