Time base circuit induction automatic light circuit

It is an induction automatic light that only uses NE:55 time base circuit . It can turn on the light when people move away and
turn off the light when people move away. Power supply}n route VD1, vS, C. , (1. Composed of R., after power on (1,
the DC voltage of about Hl 12V is transmitted from both ends to supply power to the whole machine. RP1 and VTP form a light control circuit, the photosensitive transistor VTP
is turned on during the day, and the ④ pin of NE5 55 When the level is lower than 0 4V, the circuit is forced to reset, pin ③ outputs a low level, the thyristor
VTH is turned off, and the light E does not light up. When night falls, the equivalent resistance of VTP becomes larger, or even completely cut off, and the level of pin ④
increases. , unblocking the time base circuit, thereby creating conditions for turning on the light. Adjusting RP can adjust the
light control sensitivity of the circuit.
    NE553 forms a monostable trigger
, which is usually in a stable state. Pin ③
is low level and VTH is turned off. , the light
does not light up. If the human body is close to the sensing electrode
piece, the ② pin of the time base circuit can obtain the T-frequency AC signal through the
distributed capacitance between the human body and the sensing piece
. After rectification by
VI)2, the negative half cycle of the signal can
trigger the flip of the NE555. Set,
pin ③ outputs high level . VTH is turned on, and
the lamp E is powered on and lights up.
After the person leaves, about JOs, after the transient state, the time base circuit returns to the steady state, and the lamp E goes out. If the person is
sensing If the chip continues to move within the effective detection range, the electric lamp F will be always on and the water will go out.
    In order to ensure that the circuit has sufficient trigger sensitivity, the sensing chip should be made of a thin copper sheet with an area of ​​no less than iOcm×20cm
square . And it should be inlaid with two pieces. Put it into a thin plexiglass plate with a slightly larger surface area (paste it with 502 glue). Then
embed it into the wall. The entire circuit has just been installed on the back of the sensor sheet. Note that a hole should be made on the sensor sheet to allow
the VTP to stretch a little. It should be exposed so that it can feel the natural light, but X should avoid direct exposure to its own light, otherwise the circuit
will not be able to work normally. The effective sensing distance of this circuit is about 1-3m.