DIY Kit Photosensitive Sound Light Alarm

This circuit is used to detect the ambient light. When the light is bright, it will give an audible and visual alarm, the LED will light up, and the buzzer will beep for a long time. The sensitivity can be adjusted by the potentiometer. Take an application example: call the police to wake up at dawn.

Parameter:

Supply voltage: DC 3V-5V

Board size: 2.5*3.5cm

Note:

1. Note that the components on the board are welded from a small volume and then soldered to a large one.

2. Individual components such as resistors and capacitors are temporarily out of stock. We will replace the components of the symbolic circuit with the nearby values. The blue metal film resistors may be replaced with gray carbon film resistors, and the gray carbon film resistors. It is also possible to replace it with a blue metal film resistor. It is the same effect.

3. After welding, please self-test, if the welding is not wrong, it can be successful. If the welding fails, we can only help you to check the problem. We can’t guarantee that you can succeed in welding. This is why the factory production line needs maintenance. For the reason of the work, the electronic products are broken due to static electricity, because the positive and negative poles of the power supply are connected to the wrong burnt, because of the chance of problems caused by the soldering, the wrong position of the components, etc., etc., don’t always say that the board line is problematic. This board sells tens of thousands of people, and dozens of people have problems! We promise to do our best to provide good after-sales service and try our best to help all friends to complete the production. Therefore, when encountering the finished product does not achieve the effect we have described, please do not rush to give us an evaluation, remember to contact our after-sales service, we will do our best. Thank you for your cooperation and I wish you all a happy shopping!

Circuit principle:

VR is an adjustable resistor used to adjust the sensing sensitivity, GR is a photoresistor, when the light is brighter, the resistance of the photoresistor decreases, the base current flowing into Q1 is larger, the voltage of the transistor collector decreases, D1 is lit, and R2 is limited Flow resistance. At the same time, the base current flowing into Q2 through R1 is also relatively large. Q2 goes into saturation. SP is a buzzer, it starts to sound an alarm after receiving current.