Photoelectric control hand drying circuit

Normally, the pulse light emitted by the transmitting tube in the photoelectric sensor BG is reflected by the receiving
head of J3G because there is no moving object (hand). B; The output stage (black line) is at low level, the switch tube VT is cut off, and the relay K does not act; the heating wire does not work, and the entire circuit is in a
waiting state.
    When someone needs to dry their hands, the hand close to the photoelectric sensor
will reflect the pulse light from the BG transmitting tube
to the receiving tube in the BG. After
the internal judgment of the sensor and the BG output stage (black line) is
high level , the switching tube VT is saturated. , relay K
operates, and after the auxiliary contact K closes,
the heat emitted by the electric heating wire is blown out by the electric fan to
dry the wet hands. After the hands leave, the circuit returns to static.