It is interesting to know how the indicator screwdriver works and how it works. To be aware of new products is useful. For example, filament LED bulbs can work up to 30,000 hours. This is about 10 years of relentless everyday work, exceeding the standardized by law by 25%.When they say that it is possible to measure voltages in thousands of volts in a non-contact way and check the integrity of the circuits, one begins to wonder how to use an indicator screwdriver.
It all started with simple indicator screwdrivers that reacted to a phase in a circuit. It seems awesome and curious. Inside there is a high resistance in series with a miniature gas-discharge lamp. Note that these indicator screwdrivers require an electrician to touch the back metal side of the handle. Otherwise the light is off. Not knowing this simple feature of indicator screwdrivers will not see the potential even in the place of presence or will take the neutral wire for the phase( if the indicator is the LED).The reason - the current can be formed only in a closed circuit.
With one exception - when charging capacity. It is about the human body. The first touch causes a sharp increase in current, which causes the breakdown of the spark gap of the light bulb. When released, the charge is extinguished in the tissues of the human body. It is possible to use the screwdriver again. Look at the picture: a disassembled screwdriver-tester is presented to the readers ’view. All parts are signed and folded in the order in which they were inside:
- The conductive slot of the indicator screwdriver made of steel is pressed into the plastic case tightly. Isolates the high-voltage part, blocks the possibility of a person touching it.
- A high-resistance composite material with a resistance well above the MOhm( for a direct current tester) is leaning against the conductive slot of the indicator screwdriver. This cylinder becomes a limiting resistor, reducing the current in the circuit to negligible.
- The miniature light bulb is considered the heart of the indicator screwdriver, where a discharge between two copper electrodes forms in a microscopic bubble. Due to the ionization of the contents of the sealed flask, we see a glow. You can't ring this little piece of glass like a regular fuse. Interfere with the layer of emptiness between the conductors.
- The steel spring transfers the current to the contact part of the cap that wraps around the body handle.
An indicator screwdriver device is described. All ingenious is simple. The magnitude of the current is microamps. The electrician does not feel anything, touching the site. But without this feature, the indicator screwdriver will not work. It is easy to make sure that the light starts to burn extremely long. So what is the principle of the indicator screwdriver? Think about it: there are grounding systems on the planet. During the breakdown of insulation current flows there. Where does he go?
The electrical capacitance of the Earth does not exceed 0.7 mF.Today, a small cylinder in an aluminum shell is capable of containing many times more energy. But no one connects to the capacitor. Inside the globe, the energy of an electric current is rapidly extinguished. Work is done mainly on heating the soil and radiation into space: current oscillations attenuate.
The same happens in the case of the indicator screwdriver. The socket is grounded to the person through a large radiation resistance. Inside the body, the current quickly does work and goes dead. Therefore, a person is able to tirelessly observe how the indicator screwdriver light is on. Grounding occurs through the radiation resistance of the human body. An electromagnetic wave is formed, leaving the space. This explains the fact that the products, where the LED serves as an indicator, do not need to be touched: there is no need to pierce the spark gap of the light bulb, the radiation goes directly through the contact pad.
If the first indicator screwdriver was executed simple, today everything has changed. Items even suggest replacing the tester. The capabilities of the indicator screwdrivers are so great that it became possible to register using devices of strong electromagnetic fields. This is an important feature, it is interesting for anyone, does not represent a health monitor of its own. It is worth a screwdriver a couple of hundred rubles. Easy to carry in your pocket and identify bugs everywhere.
Modern screwdrivers indicators
- Contactless registration of strong electromagnetic fields. Take a simple example - insulated wire. If a current flows through it, radiation is generated in the 50 Hz range. Most of the screwdriver indicators are tuned to the specified frequency. As a result, the instrument probe works in the manner of an antenna. To increase the sensitivity, you need to touch the contact pad with your finger. In this case, the signal, on the contrary, is subjected to amplification by internal cascades of nonlinear elements. As a result, in the hands of a person there is an object resembling a detector receiver, with a repeater antenna in the form of a human body. Advanced models have a number of modes that differ in sensitivity. The most "cool" allow you to safely work with voltages of tens of kV.This is simply amazing, especially if we recall the history of electricians affected by the discharge of current.
- Using the non-contact method it is possible to determine the presence of a phase in the circuit. This principle is based on the ability to determine the intensity of the electromagnetic field in front of the monitor. If the power flux density exceeds a specific value, for example, 5 mW per square meter.cm, the display is triggered. Or the buzzer rings. The same applies to the various current-carrying parts like the non-grounded housing of household appliances. It is enough to bring the described magic wand to observe the result. The magic is based on the fact that the input filters of most devices come out with one point on the case. This forms, in the absence of proper grounding on the metal surface of the field, recorded by a sensitive indicator screwdriver. Sometimes it is difficult to understand how to properly use the product. But now anyone will be able to independently do the necessary work.
- It is important to assess the presence of a phase in the lamp holder's turned off lamp: there is no potential there. The probe is permissible to use in normal mode, in addition, it allows you to properly position the polar switches of lamps and sconces. As you know, the device breaks the only wire, with phase. The difficulty is that the plug is plugged into the outlet is not the right side. Finally, there is a wrong installation. For example, the phase in the outlet is on the right. It is clear that the result of such work must be recorded with a marker or otherwise, so that later you do not have to do the described actions. It is especially important that the phase on the cartridge was not in the premises where they use water. Otherwise, when replacing a light bulb, an electrician literally risks life.
- A curious part of the possibilities that the multifunction indicator screwdriver demonstrates is the ability to ring the chain. The big drawback is that you have to do it through your own body. With one hand, we take up the contact pad of the handle, with the other hand - for the opposite piece of wire. Pleasing, however, the possibilities - the range of resistance reaches 100 MΩ.In this mode, the indicator screwdriver forms a working voltage on the tip.
- Similarly, check the capacitors. Then the flash is only short-lived. With one hand, take up the contact of the capacitor, to the other touch the probe. Do not forget to touch the contact area. A short flash occurs. If the polarity is reversed, the effect will repeat. This state of affairs indicates the health of the indicator. Add sting forms a positive potential. We speak in case there is a polar( electrolytic) capacitor.
- Pleased with the original proposals of designers: one thing to check the outlet with an indicator screwdriver, another - the transistor! Let us explain more clearly, let's start with the simplest nonlinear elements - diodes. It is necessary to touch the probe to the anode( the positive part, the rear arrows).Hand put on the cathode - there is looking arrow in the drawing of the electrical circuit. Do not forget to touch the contact area for the circuit and increase the sensitivity. Bipolar transistors are ringing similarly. Continue to hold your hand to the side where the current is moving along the collector-emitter junction, and poke the probe with the gauge. If the key is opened from a positive potential, it is required to close the probe to the specified area. Otherwise( negative potential) we close the side of the bare hand to the base. It is easy to guess that it is similarly possible to investigate thyristors, other elements. You need to understand how the elements work to properly dilute the potential. A number of nuances distinguishes from a simple tester. For example, a screwdriver-tester will not provide a holding current for any( even low-power) thyristor. In addition, the potential is not always enough to trigger the base. We believe that using an indicator screwdriver, it is permissible to test samples of microelectronics only. Power elements do not check.
In modern screwdrivers, indicators are batteries. So the device will be able to pick up a very weak signal. This service voltage is used to evaluate the parameters. The use of modern screwdrivers:
Extremely valuable feature of the device - when using a remote indicator screwdriver, it becomes easy to observe security measures. In addition to the above, devices of modern style allow you to check the presence of a charge on batteries, batteries.
How to choose an indicator screwdriver
Studying the counters, remember a simple rule: the indicator screwdriver with a battery is considered the most functional. This directly indicates that the device is active, contains amplifying cascades inside. That increases the sensitivity of hundreds and thousands of times. As a result, all the interesting options that were discussed today become available. There is not much difference in functionality, if, say, an indicator screwdriver with a display or a simple glass lies. The main thing is the presence of a battery.
Of course, the parameters can vary, because the prices are unequal, you should read the passport with the technical data. It says whether there is the possibility of contactless operation, what are the limits of measurement and most importantly, how to use the indicator screwdriver.
Today it is important to try to avoid unnecessary and inappropriate product. Understand clearly that a screwdriver is not suitable for serious testing of transistors, but measuring at least approximately the field strength in front of the screen is very cool. It is necessary to distinguish the functionality and prefer devices that most simply, quickly and efficiently solve the problem.