FL52C4 induction electronic greeter

1. Circuit Principle Introduction

Taking advantage of the fact that a shadow is created when a person walks past the greeter, the light change signal is received by the photoresistor. As the sensor made in this paper, the circuit principle is as shown in the figure below.

This product is powered by batteries, and the system enters a waiting state after power is turned on. When someone passes by the photosensitive device, the light intensity received by the photoresistor changes because the person's body blocks the light; this change is coupled by C2, amplified by the high gain of Q1 and other components, and input to the inverting input of IC1; this signal and the signal input by the inverting input are processed by operational amplification inside IC1 to form a control signal, which drives the audio generation circuit inside IC1 to work and generate an audio signal of "Hello, welcome!", which is converted by SP1 to make the human ear hear this greeting.

IC1 is a CMOS integrated circuit that integrates signal amplification, audio signal generation and power amplification. In order to reduce the size of the entire electronic greeter, all peripheral circuits can be integrated on a circuit board.

2. Installation and debugging

This production has fewer peripheral components and is relatively simple to make; however, due to the use of integrated packaging technology, the chip and the circuit board are directly integrated together, so the welding time cannot be too long, otherwise it is easy to damage the integrated circuit. The following picture (omitted) is a photo of the actual product for reference.

Production Instructions: This circuit is relatively simple to make, but there are certain skills when installing it. Otherwise, it will be difficult to cover the zygote.

(1) Installation of photoresistor. In this production, in order to achieve a better sensing effect, the photoresistor was treated with light absorption, that is, a black cylinder was used to install the photoresistor inside, so that the sensing signal can be better received. In order to ensure that the photoresistor can be reliably installed in the dry nut, the production process can refer to the above and below figures.

After the two pins of the photoresistor pass through the two holes of the mounting base.

Bend it and wrap it around the two small ears of the mounting base, then put the photosensitive tube on the mounting base, and solder the two leads of the photoresistor out from the bent place on the reverse side.

(2) Installation of capacitors. Since this induction greeter is relatively small, the components should be installed compactly, especially capacitor C2 and transistors, which are relatively large in size. When welding, they should be placed flat before installation.

(3) Installation of leads. In this production, the connection between the speaker, photoresistor and battery and the circuit board is completed through the lead wire. Since there is no polarity difference when installing the speaker and photoresistor, the direction of the two wires does not matter; however, when connecting to the battery, you must pay attention to the polarity, otherwise it is easy to damage the integrated circuit if it is reversed for a long time. The installation method of the battery is shown in the figure below.

The protrusion in the middle of the AGl3 button battery is the "negative" pole, and the flat side is the "positive" pole. The positive pole on the battery is marked with a "+" symbol. According to the installation method shown in Figure 6, the tongue with a spring should be connected to the positive pole, and pay attention when connecting the lead to the circuit board. The welding position of all leads on the circuit board is shown in Figure 2, where the power line is marked with a "+". "-" symbol, the speaker line is connected to the position marked with "▲", and the photoresistor is connected to the position marked with "★".

3. Operation Instructions　　

Point the photosensitive hole of the greeter toward the direction where light is shining. When someone walks by, if a human shadow can be produced at the greeter, this will have the best effect. Please understand the details according to the circuit principle.