Special dangerous restricted area prompt circuit

 (1) Circuit composition The dangerous area indicator circuit is composed of a pyroelectric infrared sensor (PIR), a signal processing circuit and a language reminder circuit.
    The signal processing circuit is composed of a pyroelectric infrared signal processing integrated circuit IC 1, a resistor ~ Rz, and a capacitor cl ~ C12.
    The language reminder circuit is composed of voice integrated circuit IC2, transistors VT1 and VT2, resistor R", capacitor cl3 and speaker BL.
    When no one enters the warning area, the @ pin of 1C1 has no signal input, and its ② pin is low level, and the language The reminder circuit does not work.
    (2) Working principle When someone enters the warning area, the pyroelectric infrared sensor will receive the human body infrared
signal and convert it into an electrical signal. This electrical signal passes through the resistor Rz After filtering out high-frequency interference signals, the low-pass filter composed of capacitors cZ, 0, etc.
is added to the @ pin of 1cl. After being processed by the circuit in IC1,
the ② pin outputs a high level to energize the language reminder circuit
. The ② pin of the language integrated circuit IC2 outputs
a voice electrical signal. After the signal is amplified by VT1 and VT2
, it drives the speaker BL to emit
a verbal reminder sound of "XX is dangerous, please do not come near."
    (3) Component selection wind, R,. All use
1/4W carbon film resistors .
    Cl, G, G, G and C8-G2 use
polyester capacitors or monolithic capacitors; Ca, .G, G, Cz. All
use aluminum electrolytic capacitors with a withstand voltage of 10V.
    VT1 uses type 9013 silicon NPN transistor;
\rl'2 uses type 8050 silicon NPN transistor. lCI uses special integrated circuits such
    as Sso001 and SNS9201 ; IC 2 uses the language of "×× is dangerous Integrated circuit .     BL uses 0.25/0, 5W, 812 electric speakers.