Light sensor LXP-02 and LXP-03. Installation

In the article, we will consider the issues of mounting and connecting the light sensor. Electrical diagrams of the most popular models of light sensors are also given.

I remind you that this device is widely used in the field of home automation to turn on / off electric lighting, depending on the level of illumination on the street. The names may be different - a light sensor, a light sensor, a light control switch or a photo relay, but the essence is the same.

I spoke in detail about such a sensor in the first part of the article -. There, its device, operation and characteristics are considered in detail.

So, I'll get straight to the point:

Light sensor connection

I will give three options for the connection diagram, they are all identical, the only difference is in the way they are displayed.

1. Scheme by analogy with a motion sensor

The connection diagram of the light sensor is completely the same as. Only the "stuffing" of the sensors differs.

The circuit is taken from the article about the motion sensor, link above.

2. Scheme from the instructions for the light sensor

Here is how the light sensor connection diagram is given in the instructions:

Light sensor LXP. Connection diagram from the instructions

3. Connection based on photo sensor

For those who like everything to be “on the fingers”, here is a picture:

A little explanation on the connection diagrams:

• Phase comes to the brown wire.
• Zero is connected to the blue wire.
• The load is connected to the red wire (the first output of the lamp).
• The second output of the lamp is connected to zero (the same place as the blue wire of the sensor)

It is worth adding that light sensors can be connected in the same way as conventional switches - in series and in parallel, if necessary. An example can be seen in the article about.

So, we figured out the connection, now

Mounting the light sensor

It would seem, what is there wiser? I screwed it on (see the picture at the beginning of the article), connected it, set it up, and that's it! But it happens that the installation site is chosen unsuccessfully, and problems begin.

In our street at one time, street lamps turned on intricately in the evening. They turn on, go out, turn on again, and so on with a period of about 1 minute. Then, with the onset of good darkness, they turned on completely.

Why is that? It's just that the light sensor was mistakenly installed in the lighting zone of the switched on lamp. It turns out: it became dark - the sensor worked - the lantern caught fire - it became light - the sensor turned off - it became dark ... And so on, a vicious circle.

Setup and Calibration

When setting up the light sensor, it is important to use the black bag that comes with the sensor. This bag serves to simulate the night.

Bag for setting the light sensor

Of the settings in the light sensor - only the light level control (LUX). It sets the level at which the sensor's internal relay is triggered.

The level setting is described in more detail in the description of the circuit diagram, below.

There are the simplest light sensors (for example, LXP-01), in which there are no adjustments at all. There are advanced ones, where there is still a regulator of the on / off delay time.

Well, now the most interesting -

Light sensor circuits

Undoubtedly, for a quick and easy repair of the light sensor, you need its circuit, according to which it will immediately become clear what is connected where and how it works. Below are a couple of sensor circuits and repair recommendations. There will be questions about the repair - ask in the comments.

The circuit is drawn exactly from the board, which is shown at the link at the beginning of the article. It should be noted that the manufacturer is constantly working on improving its device (price / quality), so the scheme may change.

Further, a constant voltage feeds the rest of the circuit, which works like this. At the output of the resistive divider 68k - VR - Photoresistor, a voltage is formed that is inversely proportional to the illumination. The VR trimming resistor with a resistance of 1 MΩ is the very “twist” with which the desired response level is set.

It is not a fact that a photoresistor is installed in such circuits, a photodiode may also be present, but the principle is the same.

If you want to save electricity - set the maximum resistance, turn it clockwise ( LUX-), and it will work when it is already completely dark.

And if you want the street lighting to turn on from the slightest cloud, turn the knob in the other direction ( LUX+).

At the onset of darkness, the illumination decreases, the resistance of the photoresistor increases, the voltage at the base of the transistor increases. And it reaches such a level that the transistor opens, a current flows through the collector, sufficient to turn on the relay KA

Knowing the principle of operation of the circuit, it is easy to repair. And if you want to understand the repair in more detail, then the article describes the methodology and philosophy of repairing such devices step by step.