One of the tasks performed with the help of photosensors is lighting control. Such schemes are called photorelay, most often it is a simple inclusion of lighting in the dark. For this purpose, a lot of circuits were developed by ham radio operators, here are some of them.

Probably the simplest diagram is shown in the figure. The number of parts in it is small, it will not work less, and the efficiency, read the sensitivity, is quite high.

This is achieved by the fact that the transistors VT1 and VT2 are connected according to a composite transistor circuit, also called a Darlington circuit. With this inclusion, the gain is equal to the product of the gain of the components of the transistors. In addition, such a circuit provides a high input impedance, which allows you to connect high-impedance signal sources, as shown in the circuit ...

The article describes the prospects for the use of graphene and carbon nanotubes in microelectronics.

Listening to the thoughtful arguments of government officials about the need to develop nanotechnology, one involuntarily marvels at the inconsistency of their actions: funds incomparable with the budget of science are allocated for defense. Moreover, now the money invested in scientific research will allow not only to radically change people's lives, but also come close to solving the problem of human immortality.

Speaking of nanotechnology, the first thing that comes to mind is the discovery of graphene and carbon nanotubes. It is with them that scientists associate a breakthrough in the field of electronics and pharmacology in the 21st century. The creation of quantum computers, signal reading systems at the cellular level, nanorobots for treating the body - this is just a small list of opportunities that open up. Now these opportunities have moved from the realm of fantasy to the field of laboratory development ...

About a common wiring malfunction when there is a phase in the 220 V sockets on both sockets. About why this is happening and why it is dangerous. First-person and a bit informal.

There is one characteristic malfunction of the wiring, which can confuse a novice or inexperienced electrician.

To clarify what I’m talking about, I’ll give a story of one of my friends: “My neighbor comes to me on Saturday - my lonely grandmother. And asks to deal with the electrician in the apartment. Say, nothing works, but the lights did not seem to be turned off. Well, I, of course, go to the site and check the circuit breakers. Everything is in order, all machines are on. I take the indicator: the phase is passing. I go into the apartment to my grandmother, I check the first outlet. The first connector is the “phase”. I check the second connector - also a "phase"! Where are the two phases from? ...

The fact that in electrical engineering it is impossible to directly connect copper and aluminum conductors is not a secret even for many ordinary people who have nothing to do with electrics. On the part of the same inhabitants, professional electricians often ask: “Why?”.

Pochemochki of any age can drive anyone into a dead end. Here is a similar case. A typical professional answer: “Why, why ... Because it will burn. Especially if the current is high. " But this does not always help. Since this is often followed by another question: “Why will it burn? Why does copper with steel not burn, aluminum with steel not burn, and aluminum with copper burn? ” To the last question you can hear different answers. Here are some of them. Aluminum and copper have different coefficients of thermal expansion. When current flows through them, they expand in different ways. ...

A modern motorist is armed with all the benefits of technological progress and most of us no longer remember how to inflate a tire with a hand-held automobile pump or apply and vulcanize a rubber patch on a car camera.

We equalize the pressure in the wheels with a compressor, we clean the interior with a vacuum cleaner, and instead of a lever bent by the letter “si”, we drive the jack with a screwdriver with a metal hook clamped into the cartridge. But all the countless electric assistants of the motorist eat electricity, so we strain our car in the garage, forcing it to work for a long time on the cigarette lighter socket to the detriment of the environment and our wallet.

Need a garage power supply: +12 volts, powerful, simple, reliable, safe and versatile. +12 volts (and preferably 12 - 15 volts) - the voltage of the vehicle's on-board network and the operating voltage of its countless accessories ...

The history of the X10 communications protocol dates back nearly four decades. It was developed back in 1975 by Pico Electronics and quickly acquired the status of the de facto standard. This happened thanks to the ingenious engineering solution: to use the electrical wiring of the house to transmit control signals.

The idea was developed in industrial PLC modems, which are used today to transmit data from electric meters through power wiring. An example is the Mercury counters of the Incotex Moscow company. But, unlike its ancestor, this data transfer protocol is closed because it uses a proprietary data encoding algorithm to achieve high noise immunity. Today, there are dozens, if not hundreds, of companies that manufacture products compatible with the X10 protocol, and Chinese manufacturers of home automation products have been added to them ...

To an uninitiated person, such a question may even seem strange. How could the idea of ​​using 12-volt luminaires and lamps in residential premises be born when the standard for household voltage in our country is 220 volts? Let's try to figure it out.

First of all, 12 volts is an ultra-low voltage, which is considered conditionally safe for human life and health. For this reason, in rooms with a high or increased degree of danger, the use of 12-volt lamps is welcomed by the rules of PUE.

Bathroom, kitchen, outdoor courtyard - these are the places in which low-voltage lighting has always been preferable. And in cramped and damp basements, it is completely impossible to operate a 220 volt network, and it is mandatory to install a step-down transformer even to power portable power consumers. 12 volt wiring does not require ...

Quite often, this situation occurs: the circuit breaker is periodically knocked out and another larger rating is installed in its place, “so as not to knock out”. Why does the circuit breaker trip in this case, and what are the consequences of such a replacement?

The rating of the circuit breaker is selected in such a way as to protect the load line wire from overheating and melting of the insulation. The circuit breaker must disconnect the line from the load before the current reaches a critical value for the cable.

When devices of higher power (and therefore higher current) are turned on in lines that are not designed for this power, the cable overheats in the circuit, which leads to the thermal protection of the circuit breaker tripping, i.e. he "knocks out" ...

If you need to replace the apartment switchboard, many questions arise.If a person does not have electrical work experience, then he is inclined to solve this problem by attracting a specialist. But is it difficult to actually replace the electrical distribution panel of the apartment?

In this article, we will consider the process of replacing a dashboard in various situations, give practical recommendations that will help to carry out this work on their own, without the help of specialists.

The complexity of the work in this case depends on the current status of the shield. Damage to the old shield due to fire is the most difficult option. The complexity of the work in this case is due to the fact that when a shield ignites, the wiring lines that are connected to it are also damaged.If the wiring lines in the shield are damaged ...

The manufacturer of the optimizer for the load on the electric network OEL-820 was contacted by an electrician serving the cottage village, and ordered a whole box of OEL-820. After some time, managers called back the buyer to find out how he operates the devices. And it was curious why he needed so many optimizers?

It turned out this. In the holiday village there is an old high-voltage transformer KTP, whose power is limited. Therefore, in the spring, autumn and winter, when energy-intensive electric heating appliances and water heaters were turned on in the houses, the total power consumption increased, and the voltage in the village electric network dropped. When turning on electric kettles and submersible borehole pumps with a high starting current, the voltage sagged still, albeit briefly. The situation was aggravated by the fact that the wiring in the houses is old, with insufficient cross-section ...

At the end of the article “An ideal operational amplifier”, it was shown that when using an operational amplifier in various switching circuits, the amplification of the cascade on a single operational amplifier (OA) depends only on the feedback depth. Therefore, in the formulas to determine the gain of a particular circuit, the gain of the “bare” op-amp, so to speak, is not used. That is just that huge coefficient which is specified in directories.

Then it’s quite appropriate to ask the question: “If the final result (gain) does not depend on this huge“ reference ”coefficient, then what is the difference between the opamp with amplification several thousand times, and with the same opamp, but with amplification several hundred thousand and even millions? ” The answer is quite simple. And in both cases the result will be the same, the amplification of the cascade will be determined by the elements of the environmental protection system, but in the second case ...

If you use an operational amplifier without negative feedback (OOS), then we can definitely say that we get a comparator. In order to understand how it works, you can do some simple, but visual experiments. To do this, you need a little: the operational amplifier itself, a power supply with a voltage of 9 ... 25V, several resistors, a pair of LEDs and a voltmeter (digital multimeter).

The simplest logic probe is assembled from LEDs and resistors. When a positive voltage is applied to the probe input (you can even supply + U), the red LED lights up, and if the input is connected to a common wire, the green one lights up. With the help of such a probe, the output state of the tested operational amplifier becomes clear and understandable. As an experimental "rabbit" any "Rabbit" is suitable for any, not very high quality and expensive...