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Electronic dog Burglar alarm circuit

Published on Feb 01 2011 // Opto Circuits

Shown anti-theft alarm, "dog" has an automatic alarm, high sensitivity, safety and reliability, low power consumption characteristics, can be used as home security, child care assistant.
How it works: burglar alarm "dogs" of the whole circuit is controlled by light switches and barking voice electronic circuits composed of two parts. Figure is a circuit diagram. VT1, VT2, and R1, R2, R3, C1, C2, etc. constitute the light control switch circuit, IC1 and VT3, R4, R5 constitute a structure such as dogs barking circuit. VT1 in the figure for the phototransistor, usually light source in the surrounding environment, it is equivalent to low-resistance resistor. VT2′s base connected to the positive potential and through R2 conduction, IC1 voice circuits are not positive pulse does not work. When VT1 blocked by an object, it generates a negative pulse voltage, coupled through C1 to the base of VT2, VT2 end result, IC2 IC to obtain a positive trigger pulses, the output audio signal is amplified through the VT3 to promote the speaker, "Wang , Wang "dog barking deterrent effect of thieves, Wensheng escape. If the electronic "dogs" at the balcony door, etc., but can prevent children climbing, to assist parents in child care purposes.
Components Selection: IC1 use MSS0287-29 barking voice integrated circuits. VT1-type phototransistor with 3DU5; VT2, VT3 are used 9013-type silicon NPN transistor such as, ß = 100. R1 ~ R5 is 1/8W carbon film resistors. C1 ~ C3 for the type of aluminum electrolytic capacitors, voltage values see Fig. BL election YD57-1 type 8O, 0.5W power speakers. SA is a small toggle switch. Power Supply 3 5 batteries. Other components as shown.

Electronic dog Burglar alarm circuit.