Use KD-9300 to make night door lock automatic lighting

The circuit of the night door lock automatic lighting is shown in Figure 3-32. It is essentially a light control and touch dual control circuit.
    SCR VS and diodes VD2~VD5 form the main loop of the control circuit. The control loop
is composed of three parts: touch circuit, light control circuit and delay circuit. Normally, transistors VT1 and VT2 are in a cut-off state, music integrated circuit A does not
work, and VT3 is also in a cut-off state. vs is in the off state because there is no trigger voltage, and the small lights Hl and H2 do not light up.
    M is the touch electrode connected to the metal door lock. When the key touches the door lock M, the clutter signal induced by the human body
is injected into the base of VT1 through R1 and R2, causing VT1 to quickly turn on. VT2 also turns on, so the trigger terminal IRI of the music integrated circuit
obtains a positive pulse trigger voltage, and A is triggered to work, and its O/P terminal outputs an electronic music signal about 20s long.
This signal is amplified by Vr3 and After R6 and C2 are smoothed, they are added to the gate of the thyristor VS to turn on VS and the lights Hl and H2 will
light up. After unlocking, the human body leaves the electrode M, and although VTI and VT2 return to the cut-off state, once the integrated block A- is triggered
, it can still maintain the output until the end of a piece of music. After 20s, as the music is played, the integrated block returns to a static
state, vs loses the trigger voltage, turns off when the alternating current crosses zero, and the lights Hl and H2 go out.
    The photoresistor RG and the transistor VT2 form a light control circuit. During the day, RO has low resistance due to exposure to light, which keeps
the base of VI2 at a low potential. Therefore, no matter whether M is touched or not, VT2 always remains in the off state, and the light
Hl and H2 will not be lit. Only when night falls and RO shows high resistance without light exposure, the circuit is
controlled by the touch electrode M. Music integrated circuit A is used here in a flexible way. Using it to complete delay control not only makes the circuit structure simple,
but also works reliably. VD1, R7 and cl form a simple resistor step-down voltage stabilizing circuit, which outputs about 3V DC voltage for the entire
control loop.