Discrete components sound and light control stairs delay switch circuit 9

A unique circuit design sound and light control delay stairs walkway lighting switch, it has a higher voice sensitivity. In the evening, when someone walking on the stairs r, f
Discrete components sound and light control stairs delay switch circuit 9 - schematic

ootsteps will make the operation of the electronic meter off, lights electric light, people no sound that is left after 30s lamp will extinguish itself. Vn3 -VD6 form a bridge rectifier circuit, by R. Limiting buck, vs regulators, c m filtering lose about 9V DC voltage for transistors VT1-VT4 sheet j electricity. RL daytime photoresistor resistance was low, VT3 conduction, VT4 off. In this case C. In particular on the voltage, VT: i deadline, VT6 conduction, VT7 thyristor gate and cathode are VT6 shorted. VT7 father off, lamp E does not shine. Night, RL light irradiation, showed a high resistance, but ran in biasing R makes VT1 conduction, VT1 emission catch eight VT3 base current flows, so VT3 still in a conducting state, so in a quiet state, lamp It will still not be electrically lit. J stairs when someone walking their footsteps or conversation after picking microphone B, m corresponding to the input signals Yi to the VI] zoom. After the release of the audio signal and the Yili Ding v 1 emitter VT3 injected into the base of the other aspects of the VT1 collector catch output by C. Coupled to the base VT2, VT2 signal by amplifying its lake collector output m away again to shake VT1 base. Thus called See, VT1 and VT2 composition TF feedback audio amplifier, it has a very high gain of the circuit, the circuit thus has a high voice sensitivity, this is the clever design of the circuit lies. Since V T3 group has a strong pull audio signal input, the negative half cycle of the signal makes its exit VT3 conduction state, state and even zoom into the off state. VT3 collector electric ft rise. vr4 conduction, 9V DC voltage by VT4, VD2 to (rapid charge, and so by R. T5 is turned on, VTfi off, lift the VT7 thyristor gate closure gate lock .V T7 by the R-, obtained only to trigger current, VT7 opened, lamp E on the light-emitting electric lamp is lit, the light itself into a low resistance although so R1J make VT3 conduction blockade, but because C. has full charge, C, by R. to VT5 emitter discharge, VT5 still maintain an on-state, so the lights continue beetle bright rug. f when discharged, VT5 off, VT6 conduction, VT7 off, lights off as Tiao have sound again, women fork electric energy lighting delay circuit when IHj abundance determined by R., G discharge time constant, the icon data about 3.s. white days, because VT3 blockade, then a loud noise it will never lamp lighting. WRI, VT:/requirements magnification p values greater than 200. the other transistor p value of about 100 is appropriate. VT5, VT6 of pVceo require some as high as possible electret condenser microphone B best selection of better stability. with white spots the subject of the kind of package. other components shown in Figure parameters, no special requirements.

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