During the operation of classic light switches in offices and residential buildings, they often fail. This situation is due to the presence of rubbing parts. Today, such devices are increasingly being replaced by more reliable and high-quality models of touch switches. The principle of operation and design of these products are distinguished by their simplicity and affordability. Due to this, even a beginner can make a touch device with their own hands.
Design
To make a touch switch with your own hands, you need to understand that the peculiarity of this product is that it is enough for an ordinary user to touch a certain contact field with his fingers, and he will get the same result as when working with a standard keyboard unit. But the principle of operation of the improved device has its own differences. Most often, the design of the sensor device is based on four working nodes:
- electronic board;
- protection panels;
- case;
- contact sensor-sensor.
There are several common models that are distinguished by durability, reliability, quality and appearance. The master can try to create a touch switch with a brightness control with his own hands. There are options that monitor the temperature in the room, as well as raise the blinds on the windows.
Working principle
Before you start making a touch switch with your own hands, you need to consider the operation of the device. The electronic part is most often represented by a cascade amplifier that processes the signal coming from the main panel. It is this node that raises the amplitude of the incoming wave to the desired level. This option is relevant for switching small current loads. The static electricity available on the human body is quite enough to open the input transistor. Manufacturers often install three cascades at once in order to eventually achieve the desired coefficient. If the master wants to make a touch switch with his own hands, then a load relay can be included in the general circuit (instead of a classic resistor). Such a product is of better quality and more reliable.
Benefits
Classic and walk-through touch switches boast numerous positive features. The main ones include:
- Quiet operation of the main executive module, which is built into the switch.
- Practicality of the installed switching pattern.
- Complete safety of operation of the product, as power is supplied through galvanic isolation.
- Modern look that will fit into any decor.
It is worth noting that advanced products can be touched even with wet hands, which is not recommended for keyboard instruments. Setting up the touch switch is not a difficult process, thanks to which the master can complete the mechanism with a remote control system.
Functionality
Setting the touch switch compares favorably with the fact that another useful feature has been added to the device - a built-in timer. Due to this, users can control the switch programmatically. For example, you can independently set the on and off times. Optionally, you can also add an acoustic sensor to the device. In this case, the unit will function as a kind of noise and motion controller. The user only needs to give a voice or clap their hands loudly, and the light in the room will light up. If you need to adjust the brightness, then you should additionally install a dimmer. Due to this, it will be possible to control the intensity of the light flux. After studying the basic scheme, you can figure out how to make a touch switch without any extra financial investment.
Relationship of mechanisms
In order to properly connect the touch switch, you need to know what each node is responsible for. The classic device functions as follows:
- A weak signal is formed on the sensitive element, which is fed to the input of the installed microcircuit. At this point, the incoming information wave is amplified to the desired value, after which it is fed through the transistor to the control electrode of the triac. All manipulations are performed in a split second.
- The opening time of the output control is adjusted depending on the duration of the transistor on.
- If the user keeps his fingers on the switch for a long time, then the current in the supply circuit will increase rapidly. In such a situation, the illumination in the room will also increase.
- To turn off the light, you need to keep your fingers on the sensor and after reaching the maximum brightness of the light flux.
If a beginner wants to understand how the sensor works, then he needs to study the classic circuit of the unit in detail. You can use ordinary copper foil to make your own sensitive pad.
Connection rules
The installation of the touch switch corresponds to the classical scheme, which is designed for keyboard products. Almost always there are two terminal contacts on the rear panel: under load and input. High-quality switching in the product circuit is carried out along the phase line. A conductor is applied to the input, and the voltage for the load is removed at the output. In some cases, the design may consist of several independent sections. Because of this, the number of terminals for connection is increasing. Not toget confused, you need to follow the classical scheme. The design of the switch is made in such a way that it is freely placed in traditional sockets. The chassis is fixed with strong screws.
Homemade Devices
When the master has studied the principle of operation of the touch switch, he can try to make the device with his own hands. In this case, you can save a pretty decent amount, since the finished device costs at least 2 thousand rubles. If the master has minimal skills in handling electrical engineering, then it will not be difficult for him to build a touch switch. The main thing is to prepare all the necessary tools and materials in advance.
Elementary version on relays and transistors
This method can be mastered even by a beginner. The master can apply almost any relay. The main requirement is that the operating voltage range should be between 5 and 12 volts. The unit must switch the load in the 220 V network. The touch switch is made by carefully cutting out a getinax foil sheet. Transistors can be of any series. Experts note that this circuit is represented by a classic signal amplifier. When touching the surface of the sensitive sensor, a potential appears at the base of the transistor, which is quite enough to open the emitter-collector junction. After that, voltage is applied to the relay coil. The device is triggered, and the contact group is closed, which leads to the inclusionlight.
Use of infrared sensor
This element can be safely used to make a universal switch. According to the scheme, the master can also use inexpensive electronic mechanisms. It should be noted that the degree of complexity of this option is designed for experienced professionals. As a base, you must use two microcircuits, as well as the following details:
- photodetector;
- regular LED;
- relay;
- Infrared LED.
The pulse generator will help to assemble an inverter chip. If a biological object appears in the area of action of the infrared LED, a pair of infrared LED and a photodetector immediately fires. On the basis of a classic transistor, a control signal is formed, which turns on the relay. If there is no active movement in the sensor coverage area, then after 20 minutes of inactivity the meter will count a certain number of pulses from the flashing LED, which is enough to turn off the relay. The lamp will go out. It should be noted that the waiting time is determined by the selection of circuit elements.
Trigger universality
For the most part, touch switch circuits are simple and affordable. In the circle of radio amateurs, microcircuits are the main link in a device that you can assemble with your own hands. The trigger state can be changed by applying a control signal to its output. It is this property that is successfully used to implement the switch function. The universal output circuit is built with the addition of a field effect transistor. It is this unit that provides high sensitivity, and also qualitatively isolates the contacts. The main element of the sensor can be independently made from a metal plate and connected to the “field worker” input. Due to this, it will be possible to guarantee the complete safety of the unit for the end user in terms of possible electric shock. A universal transistor can amplify the existing signal that comes from the microcircuit. The thyristor plays the role of a multifunctional switch. A lighting device must be included in the circuit, which also needs to be controlled. The circuit functions as follows:
- First of all, the user touches the installed metal plate (sensor).
- The generated static electricity is fed in.
- The FET switches the trigger.
- The output signal is amplified to the desired levels.
- The thyristor opens.
- The lamp lights up.
If the user again touches the sensor with his hand, then all operations will be repeated, but only in the reverse mode switching. Everything is quite simple and effective. Such a scheme can be used to control luminaires, where the total power of incandescent lamps is within 80 watts. If you need to switch more powerful mechanisms, then you should include a cooling radiator in the circuit.
