Description of a simple device that disconnects the load if the mains voltage goes beyond acceptable limits.

The tolerance for the mains voltage for powering household electronic and just electrical equipment is plus or minus 10%. But in the conditions of the domestic energy supply system, this requirement is often not complied with.

The voltage can be significantly too high or much lower than normal, which can lead to equipment failure. To prevent this from happening, the article describes a simple device that will disconnect the load on time before it has time to burn out.

A diagram of a fairly simple protection device is shown in the figure ...

Description of a simple LED garland control circuit.

Now it’s not a problem to buy a Christmas garland with a controller: there are a sufficient number of Chinese-made flashing lights on sale.

It would seem that he went, bought everything. But it will be much more pleasant if the garland is created with your own hands. It will help revitalize old garlands inherited from grandparents along with old Christmas-tree decorations.

Such a control device (controller, automatic lighting effects) is not at all difficult to assemble. It is enough to make a printed circuit board and solder several parts into it ...

The design of a simple timer that allows you to turn on and off the load, at predetermined time intervals. The operating time and pause time are independent of each other.

The use of timers in everyday life has now become quite common. Therefore, such a device can simply be bought at an electrical goods store. Most often, these are multichannel timers that allow you to program switching on / off at a certain time of the day, and even taking into account the day of the week.

But sometimes a timer is required that works simply according to the “work - pause” algorithm. You can turn it on simply by hand, but the operating time and pauses can be adjusted independently of each other. One of the examples when such a time relay may be needed is the “Chizhevsky chandelier” ...

A simple circuit for determining short “dips” in mains voltage.

Everyone knows about the low quality of domestic energy supply, and a lot has been said about it. Instead of a voltage tolerance of +/- 10 percent, which is 180 ... 240 V, the mains voltage can "float" in the range of 160 ... 260 and more V.

Such slow voltage changes are quite successfully handled by AC voltage stabilizers based on autotransformers, for example, Resanta. Such stabilizers are designed mainly for such equipment as a refrigerator, washing machine, electric stove.

Modern electronic household equipment does not require such stabilizers, since all voltage stabilization is carried out, as a rule, by internal semiconductor stabilizers ...

The article explains how to remake a conventional computer power supply for a voltage of 24 volts.

In some cases, there is a need for powerful power supplies for various equipment, designed for a voltage of 24 volts.

In this article I will tell you how you can remake a conventional computer power supply both ATX and AT for a voltage of 24 V. Also, from several such blocks, you can compose any voltage to power all kinds of devices.

Alteration is the addition of two power diodes, an inductor and a capacitor ...

The scheme of a single vibrator and the principle of its operation according to the time diagram.

In the previous part of the article, multivibrators made on the K155LA3 logic chip were described. This story would be incomplete if not to mention one more kind of multivibrator, the so-called single-vibrator.

A single vibrator is a single pulse generator. The logic of his work is as follows: if a short pulse is applied to the input of a single-shot, then a pulse is generated at its output, the duration of which is given by an RC chain.

After this pulse ends, the single-shot goes into the standby state of the next trigger pulse. Because of this, a single vibrator is often called a standby multivibrator. The simplest single-shot circuit ...

A regulator that supports mains voltage within 190 ... 242 V.

It is known that voltage in domestic power grids often goes beyond tolerance limits. In the days of tube TVs, ferroresonant stabilizers were very common. Modern TVs are operable with changes in input voltage within 110 ... 260 V.

The same can be said about computers, CD players, and generally about all the equipment in which switching power supplies are used. But for equipment that feeds directly from the network, the limits of voltage change are much smaller.

A vivid example of such a technique is a refrigerator, an electric coffee grinder, a food processor, a soldering iron, an incandescent lamp ...

Soft start of the electric motor has recently been applied more and more often. The fields of its application are diverse and numerous. This is industry, electric transport, utilities and agriculture. The use of such devices can significantly reduce the starting load on the electric motor and actuators, thereby extending their service life.

Starting currents reach values ​​7 ... 10 times higher than in the operating mode. This leads to "subsidence" of voltage in the supply network, which negatively affects not only the work of other consumers, but also the engine itself. The start-up time is delayed, which can lead to overheating of the windings and the gradual destruction of their insulation. This contributes to premature failure of the motor ...