Non-two-wire sound and light control stair delay switch circuit (3)

It is a sound and light controlled stair delay lighting switch circuit made of NEr5S time base circuit.
It has the characteristics that the circuit is relatively simple and the effect is good.
    (j, (1:, VD, vs form
a capacitor step-down half-wave voltage stabilizing
circuit. After power on, both
ends of G can output
a DC voltage of about 12V for the time base lb circuit
NE5 5j. The time base
circuit is connected For a typical monostable
trigger, the circuit is usually in
a stable state, pin ③ outputs low level
, transistor VT3 is turned off, and
the light F does not light up. VT1 and WF2
form a sound-activated trigger circuit, and
RI is a photosensitive resistor. During the day. R]. The low resistance has a great shunt effect on the piezoelectric ceramic piece B, so the sound
control sensitivity is greatly reduced. The sound wave signal output by VT2 cannot make VT1 conductive. The state of NE555 will not
change. In the evening, RL appears High resistance can be regarded as an open circuit. At this time, B feels the sound of human footsteps or conversation after being amplified by VT2 and coupled through (1. The positive half-cycle peak of its signal causes VT1 to turn on instantly, that is, to the ② pin
of NF555
Input a negative pulse. NE555 quickly sets the bit and enters the transient state. The ③ pin outputs a high level , the transistor VT3 is turned on, and
the lamp E) lights up. After about 1 1R.G, the ⑥ pin level of the time base IU circuit rises to 2/3Vnn, the transient ends, and the circuit
returns to the original stable state. ③Pin input I|} is low level , VT3 turns off when the AC power crosses zero, and the light E goes out.
    VT1 and VT2 require an amplification factor p value of 300 -400Q 9014, type silicon transistor. C.
Thirty-cim-,ioov polypropylene capacitors should be used. Other Jc device parameters are shown in the figure, and there are no special requirements.