Simple and affordable inductive electronic welcome

Photocoupler

First, the introduction of the circuit principle

When a person walks past the welcoming device, a shadow is generated, and the light-receiving signal is received by the photoresistor. As the sensor of this production, the circuit principle is as shown below.

The production is powered by a battery, and the system enters a wait state after power-on. When someone passes through the photosensitive device, the light intensity received by the photoresistor changes because the human body blocks the light; this change is coupled by C2, and is amplified by the high gain of Q1 and the like, and then input to the inverting input terminal of ICl; This signal and the signal input at the non-inverting input are processed and amplified in ICl to form a control signal, which drives the audio generating circuit inside IC1 to work, and produces an audio signal of “Hello, welcome!”, and the electroacoustic is completed by SPl. Conversion, so that the human ear can hear this greeting.

lC1 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 welcome device, all peripheral circuits can be integrated on one circuit board.

Second, installation and commissioning

This production has fewer external components and is simpler to manufacture. However, since the integrated package technology is used, the chip and the circuit board are directly integrated, so the soldering time cannot be too long, otherwise the integrated circuit is easily damaged. The picture below is a photo of the real thing for reference.

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

(1) Installation of the photoresistor. In this production, in order to have a better induction effect, the photosensitive resistor is subjected to light absorption treatment, that is, a black cylinder is used to mount the photoresistor therein, so that the sensing signal can be better received. In order to allow the photoresistor to be reliably installed in the dry zygotes, the fabrication process can be carried out with reference to the above figure and the following figure.

The two terminals of the photoresistor pass through the two holes of the mount.

The bend is wound around the two small ears of the mount, and then the photosensitive is simply placed on the mount, and the two leads of the photoresistor are welded from the opposite side.

(2) Installation of the capacitor. Since this inductive welcome device is relatively small, the installation of components should be relatively compact, especially for capacitors C2 and triodes, due to the relatively large size. The soldering should be considered after flat mounting. See Figure 4 for details.

(3) Installation of leads. This is in production. The speaker, the photoresistor and the connection between the battery and the circuit board are all completed by the lead wires. Since the speaker and the photoresistor are not polarized when installed, the two wires do not have a direction; however, the connection with the battery must pay attention to the polarity. Otherwise, if it is reversed for a long time. Easy to damage integrated circuits. The installation method of the battery is shown in the figure below.

The AGl3 button cell has a "negative" pole in the middle and a "positive" pole in the plane. The positive pole on the battery is marked with a "+" symbol. According to the installation method shown in Figure 6, the spring-loaded tongue should be connected to the positive pole, and care should be taken when connecting the lead to the circuit board. The soldering locations of all leads on the board are shown in Figure 2, where the power cord is labeled "+". The "one" symbol, the speaker wire is connected to the position marked "▲", and the photoresistor is connected to the mark marked "★".

Third, the operating instructions

The photosensitive hole of the welcoming device is directed toward the direction in which the light comes in. When someone walks by, if a person is able to produce a figure at the welcoming device, this has the best effect; please understand the circuit according to the circuit principle.