We all know that the main job of electronic engineers is the design of electronic products. Any electronic product can be thought of as being composed of a housing and a circuit board. The core technology of an electronic product is the design of a circuit board, and the design and manufacture of a circuit board will enable us to master the core technologies for designing and manufacturing electronic products.
A simple fire alarm overview
If the device is used in a place where it is easy to catch fire, such as in a warehouse, an alarm will sound when there is an open flame, and the alarm will stop when the open flame disappears.
Second, simple fire alarm circuit schematic
Third, simple fire alarm circuit analysis
The resistor R1 and the infrared receiver diode VD1 are connected in series to form a series voltage divider circuit. The signal is output from the negative terminal of VD1 and sent to the base of the transistor VT1. The transistor acts as a switch and controls whether the buzzer sounds.
When the 5V power supply voltage is turned on, the infrared diode is in the reverse cut-off state because no infrared light is received, and the voltage output from the negative terminal of VD1 is a high level and is sent to the base of the transistor VT1 so that the transistor is turned off and the buzzer is turned off. The device does not ring.
When using a lighter to light a fire (simulation of a fire), the infrared diode receives infrared light and is in a conducting state. The voltage output from the negative electrode of VD1 is a low level and is sent to the base of a transistor VT1, so that the transistor is in a conducting state. The buzzer sounds.
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