Unusual use of the adjustable zener diode TL431. Simple temperature controller. Description and scheme

Anyone who has ever been involved in the repair of modern computer power supplies or various chargers - for cell phones, for charging "finger" AAA and AA size batteries is well aware of the small detail TL431. This is the so-called adjustable zener diode (domestic analogue of KR142EN19A). Here it truly can be said: "Small spool, yes dear."

The logic of the Zener diode is as follows: when the voltage on the control electrode exceeds 2.5 V (set by the internal reference voltage), the Zener diode, which is essentially a microcircuit, is open. In this state, current flows through it and the load. If this voltage becomes slightly less than the specified threshold, the zener diode closes and disconnects the load ...

Almost every beginner amateur radio seeks at the beginning of his work to design a network power supply, so that later it can be used to power various experimental devices. And of course, I would like this power supply to “tell” about the danger of failure of individual nodes in case of installation errors or malfunctions.

To date, there are many schemes, including with an indication of a short circuit at the output. In most cases, such an indicator is usually an incandescent lamp included in the load gap. But with this inclusion, we increase the input resistance of the power source or, more simply, limit the current, which in most cases, of course, is acceptable, but not at all desirable ...

According to existing Russian standards, consumers are supplied with single-phase power supply with variable characteristics, that is, with alternating current.

The rated voltage is 220 volts with a frequency of 50 Hz. But there are such cases that sharply pop up in rural areas and in summer cottages, when we need to connect a three-phase electric device to work.

An example of such a device is a power-saw bench, powerful pumps, electric tractors, various types of threshers and meat grinders, concrete mixers. So where to get these two missing phases? In fact, there is nothing complicated in this and will be on the shoulder of anyone who is more or less versed in electrical engineering and energy.

Usually in such cases, we are advised to purchase a portable generator. But you can do without it, or at least use the cheaper option - a three-phase asynchronous motor with a squirrel-cage rotor ...

Circuit-breaker circuits allow turning on and off lighting from two or more different places for their installation. In some cases, this is not only convenient, but also very necessary.

For example, there is a long corridor. It is naturally lit. Turning on the light at the beginning, and having this very scheme of connecting the passage switch, you do not have to return again to turn it off, but you can do this with the second switch that is installed at the other end of the corridor.

Let's take a closer look at this wiring diagram, consisting of two loop-through switches. It will require two switches (they are also called “walk-through”), each of which has three contacts and two switching positions. Moreover, the switching mode must be of "cross over nature", that is -one contact is common to the other two.In one position it is closed with one of them, and in another position, naturally, with another ...

In damp rooms, garage boxes in the "pit", and other safety rooms, it is required to install lamps with 12 Volt lamps. To power such lamps, a step-down transformer is used.

In addition to conventional transformers, electronic pulse transformers have recently appeared on sale. However, when used to power the luminaires, a voltage of 12 volts with a long wire length of the lamp starts to burn dimly, at full heat. Let's try to solve this problem.

Recall physics. The power of an incandescent lamp is 60 watts, the voltage from the transformer is 12 volts, from here we calculate the current: 60/12 = 5 amperes. If a current of 5 Amps flows through 220 Volts, then the power will be 1.1 kW. With a large current, a voltage drop occurs, the voltage drop depends on the length of the wire and its cross section. A voltage drop of 5-6 volts at a voltage of 220 volts is not so noticeable, but at 12 volts this is half the voltage ...

When designing or repairing appliances, household equipment, the problem often arises: how to weld certain parts. Buying a welding machine is not easy, but making it yourself ...

In this article you can get acquainted with a simple home-made welding machine, made according to the original scheme.

The welding machine operates on a 220 V network and has high electrical characteristics. Thanks to the use of the new form of the magnetic circuit, the weight of the device is only 9 kg with overall dimensions 125 x 150 mm. This is achieved by using a tape transformer iron rolled into a torus shape, instead of the traditional package of W-shaped plates. The electrical characteristics of the transformer on the magnetic pipe are approximately 5 times higher than that of the W-shaped, and the electrical losses are minimal ...

To conduct water supply and sewerage, to make open-air cages for pets and birds, beautiful flower stands and many other things useful in the household, a welding machine made of available parts and materials will help you. With electrodes up to 4 mm in diameter, they can weld metal with a thickness of 1 - 20 mm. The home-made welding machine operates on AC 220 or 380 V.

Its basis is a three-phase step-down transformer 380/36 V, power 1 - 2 kW, designed to supply a low voltage power tool. Even a copy with one burned-out winding is suitable.

Without disassembling the core, remove the secondary windings from all the coils by biting the copper bus in several places. Do not touch the primary windings of the extreme coils, and rewind the middle windings with the same wire, making bends every 30 turns ...

In a dark room, the light switch always has to be looked for by touch. This task is facilitated by the “firefly” installed on its decorative panel - a luminous neon bulb or LED.

Connect a neon bulb or LED of the AL102, AL307, KL101 and other series in series with a resistor of 100 - 500 kOhm or 100 - 200 kOhm to the terminals of the wall switch. Instead of a neon lamp, you can use a starter for a fluorescent lamp.