As shown in the figure, the electronic model consists of two sounding circuits, each consisting of a photoelectric sensor head, a 555 and a voice circuit.
The photoelectric sensor head adopts 3DU type photosensitive tube. When the guest exits the entrance port, the light of the VT1 (or vT3) is blocked, the photosensitive tube is high impedance, and the potential of the 555 2 feet is less than 1/3Vdd trigger level, then IC1 ( Or IC2) is set, the output is high, so that IC3 (NS5603) is triggered, and the voice of "Welcome" is issued. At the same time, VT2 is turned on, and the low potential of its collector is applied to pin 4 of IC2, which will force reset 555 regardless of whether VT3 has illumination.
Bluetooth Mini Projector
Sound can be transmitted wirelessly, no audio source cable is required.
1. The Bluetooth function of the projector can be connected to a Bluetooth speaker, and you can enjoy better sound quality when watching movies and playing music;2. After the projector is connected to the mobile phone through the Bluetooth function, the projector acts as a speaker and can play music from the mobile phone.
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Shenzhen Happybate Trading Co.,LTD , https://www.happybateprojectors.com