Warning Buzzer & Chime
The kit contains a complete set of components, circuit boards, supporting drawings, and component lists.
Board size: 5 * 3.5cm; Power supply voltage: DC 5V; Weight: 10g
1. Function introduction:
RP1, R1, R2, R3, and RT constitute bridge for measuring temperature in the circuit. When the temperature is below the preset temperature, the potential of 2 feet of UA741 is higher than 3 feet, and the output of 6 feet of 741 is low level. LED1 is on, and the buzzer does not sound, which means no alarm. When the temperature rises, the resistance of RT drops 741. The 2-foot voltage drops with it. When the 2-foot voltage is lower than the 3-foot voltage, the 6-pin outputs a high level and starts to alarm. LED1 goes off.
Welding precautions:
1. The PCB board is printed with silk screen marks of various components. Please compare the silk screen marks and weld them;
2. Resistance has no direction, but there are different resistance values, please pay attention to distinguish when welding;
3. Electrolytic Capacitor. LED lights are divided into positive and negative poles. Long feet are positive (+) and short feet are negative (-). Pay attention to the silk screen direction on the PCB board when welding;
4. When connecting wire to wire holder, pay attention to distinguish positive and negative poles, and do not reverse.