Digital circuit sound and light control stair delay switch circuit (5)

use. The D401/9 integrated circuit is a sound and light control stair stop delay switch, and a voltage}U
ceramic chip is used as the electric transducer. The performance of the political circuit is good and the work is stable and reliable.
    The inverter III and the photosensitive diode VDP form a light control circuit. During the day, VDP has low resistance, and pin ⑤ is low level .
After gate III and gate V are inverted, , ⑥ pin outputs low level. VD1 cutoff. The ⑩ pin of r J vs input terminal tiP is low level because it is grounded
, and the gate V and gate VI are inverted. The ⑧ pin is low level, so the transistor VT has no trigger current and
is E does not light up. At night, VDP is high in voltage early in the morning, and the level of pin ⑤ of (1r)4()69 in static state is mainly controlled by R. Determined by the partial pressure with RJ
, because R#>R. , so U/TJ does not reach the f J circuit flipping level, the circuit status Al< will change, and the power source will still not light up. The inverter
gate lfqr linear amplifier, if at this time, when the piezoelectric ceramic piece B senses the acoustic signal, it is amplified by f JJ and
inverted , the ④ pin can output a forward rectangular wave through C, coupling, so that the ⑤ pin becomes It is island level, and the circuit state flips. ⑧The output of pin 8
is high level, which is added to the gate of VT via R, causing VT to trigger and turn on, and the circuit E will be energized and emit light. at the same time. f¨町
is fully charged through VD1. After the audio signal disappears, pin ⑤ and pin @ return to low level. At this time, G can be discharged through R and still keep
pin ⑩ at high level , so the lamp can still keep lighting.