Screwdriver voltage indicator for home
It is worth saying right away that the indicator screwdriver is a very important tool, which, on a par with pliers and a hammer, should be in any home and apartment.
Almost everyone has been in such an unpleasant situation. the light in your apartment goes out unexpectedly. What happened? Why it happened? Most people immediately wonder, “Is it just me or is the light out everywhere??”Well, if you have an indicator screwdriver handy, you can find the answer to this question very quickly. over, having a minimum set of skills, in some cases you can even fix the problem yourself.
For example, if the switch or socket simply lost contact, you can fix the breakdown very quickly. just look for the problem area. But how to do it? Use special, cumbersome, complicated and rather expensive devices? Not if you have a screwdriver at hand. And if you use it, you do not have to dismantle the wall to get to the wiring.
A serious plus is that no one needs to be taught how to use the screwdriver indicator. it is as easy to use as possible. And it allows you to instantly determine the absence or presence of voltage on the switch or in the socket.
What the indicator screwdriver is for
This tool is essential when you need it:
- find out the causes of electrical appliance breakdowns;
- Determine where the phase wires are broken;
- To figure out the wiring;
- check whether the socket is working;
- install a new socket;
- determine the purpose of the wires when connecting an electrical circuit.
In other words, you need a screwdriver to accurately, but safely, detect the presence of electrical voltage in the wires. Thanks to this device, the repair and adjustment of electrical appliances and equipment, as well as the laying of electrical circuits is greatly facilitated.
Important to know: The indicator screwdriver should not be used like a regular screwdriver, as this can render the tool unusable.
What the indicator screwdriver shows
This device indicates the presence of electrical voltage in electrical appliances and wires. These tools are needed to safely determine phase and zero on their own.
Data on indicator screwdrivers can be displayed:
A normal (simple) one with a neon bulb
The simplest type of indicator screwdriver is only good for checking if there is a phase. You can also call it an electrical probe (tester), because you can’t do anything else with it, you can only “try” to see if there is voltage. Zero is “found” by elimination only. Another way to find the breakage (or lack of contact in relay circuits), but this requires the device to be energized.
There are two types of simple screwdrivers. They can be distinguished by their appearance. Some have only a stinger and a plastic handle, others have a metal contact patch on the end of the handle. The first type (no contact) is “self-contained”. To detect voltage, you only need to touch the sting to the current-carrying conductor. if there is voltage, the light bulb will light up. But such probes are rare, more often they can be found to work in a low voltage network. 12-36 V. When using a second kind of indicator screwdriver, to see if there is a phase, you must additionally touch the contact pad on the handle with your finger. Without it, the indicator will not light up because there is no electric current flowing through it.
The design of a simple indicator screwdriver
Before you use the indicator screwdriver, it is desirable to know how it is constructed. this will make it easier to use in the future. The design of a simple screwdriver to check electricity is not complicated at all. The circuit is as follows: screwdriver stylus, resistor (1 megohm), neon lamp, spring and contact plate/sensor as a button on the handle. When you touch the button, a circuit is formed of which your body is a part. As a result, the neon bulb lights up. The current flow is very small because it is limited by the resistance.
If you only need this functionality (check the phase and find a break). this is one of the best options. And it is the most inexpensive. Such a screwdriver costs from 20. The disadvantage is that it will not show anything at low voltages. If the voltage is below 70-60 V, it is useless.
There are several kinds of indicator screwdrivers. Let’s look at each one in more detail and examine their principle of operation.
With integrated lamp
The simplest and most primitive indicator tool is an ordinary screwdriver with an integrated lamp. It does not have an active power supply.
The principle of operation is very simple and ingenious. Once voltage is applied to the tip of the stinger, it passes through a resistor that is built into the handle. After the resistor, it goes to the lamp. On the end part there is a metal plaque, which acts as a second contact.
In order to detect the absence or presence of voltage, you need to cover the plaque with your finger when the stinger of the tool touches the surface. Such a screwdriver is notable for its low price because it can only detect phase and zero.
On the battery
Indicator screwdriver with battery. It can be said that this is an improvement of the previous version. It has a battery built in and acts as a power source. It is also equipped with a bipolar transistor. This tool differs in that it has an expanded set of features, because it allows you to determine the phase and the zero:
In addition, such an indicator tool allows you to find hidden wiring, but the error will be quite high.
You no longer need to cover the metal tab with your finger to check for voltage. Such a screwdriver is the most popular, widespread and versatile indicator tool.
Tester with an electronic unit and LCD screen. It has an audible alarm that goes off when there is voltage in the mains. The most modern version of this type of tool. With the tester, you can determine the current voltage of an electrical network, ranging from 12 to 220 volts. The LCD display shows the numerical value of the mains voltage.
Reference. In fact, such a screwdriver is a multimeter, but in a very simplified version.
Many experts believe that it is unreasonable to buy such a tool, and there are two reasons for this:
- the cost of such a tester is 3-5 times higher than the cost of the previous version;
- in case of breakage of any of the elements, the repair will be energy-consuming and time-consuming. over, it is quite rare to find parts for such an indicator on the market, so if a malfunction occurs, you will have to buy a new tool.
PHASE SEARCH AND ZERO TEST IN THE SOCKET BY INDICATOR
As I said before, the main purpose of any screwdriver is to detect PHASE and ZERO. And if the passive phase indicator, can only tell you the phase and zero you determine by the residual principle, in the active screwdriver, you can identify both.The easiest way to demonstrate the operation of this function is to identify the phase and zero in a household socket.
To find the phase by hand touching the top contact of the indicator is not necessary, just holding the screwdriver by the plastic handle, we press the sting to any contact in the socket. If the LED in the housing of the indicator lights up. it means that on this contact phase.
If the LED is not lit, but if you touch the top of the indicator with your hand, the contact pad on the end cap, if it is lit. it means that on this contact, there is a zero and it is not interrupted.
In this way, you can determine the presence of electrical current not only in the socket, but also on the contacts of electrical equipment, cables, and even, in certain cases, on the bodies of electrical appliances, pipes, or heating radiators. And also to check the zero or grounding functionality.
This principle is the basis of all tester screwdrivers. However, their options and the number of technical designs are very large today:
- Simple testers are screwdrivers with the standardized set of operating elements described above, and a hollow plastic housing. For indication, as a rule, neon lights are used, and the zero phase is directly a person touching the contact plate. The scope of use and functionality of the screwdriver is somewhat limited by the fact that the product does not work at line voltages less than 60V. Determine the contact core, check the phase with a screwdriver can be used, but to find a break in the circuit. hardly possible.
- Testers with LEDs. These devices are slightly different from the above-described by their design and, of course, by their functionality. Using LEDs as indicators makes it possible to test circuits with voltages under 60 V. Correspondingly, the device can be used to test internal circuits of electrical equipment, determine the integrity of fuses, wires, open circuits. Screwdriver testers of this type often use bipolar transistors and an autonomous power supply, and make contactless testing possible.
- Universal screwdriver testers have the most extensive capabilities: short-circuit testing of power circuits, no-contact and contact testing, sound and light indication, identification of open circuits. Besides, they have a pretty low response threshold, so they can be used for adjusting and repairing AC and DC circuits in transportation, household environments, electronic devices, etc. д. The main disadvantage is that they have their own power supply. If the battery dies, the tester will be completely useless.
The choice of a particular device is directly related to the totality of the work that needs to be performed with its help. Directly in the categories there is little difference between the devices. screwdrivers are simple in performance, so budget products in quality are inferior to more expensive.
How to use a simple tester
This section will deal with simple indicator screwdrivers that have a neon bulb inside. Naturally, they are suitable for the most basic tasks. to determine the load on the socket or find a phase wire in the cable. To do this, you need to take the socket in your hand so that one finger is tight at the end of the handle to the contact area, and the other fingers are not in contact with the sting of the socket (it passes the current of 220V).
Then the probe is inserted, one after the other, into each opening of the socket that is suspected to be energized. During contact with one of them, the indicator light turns on. If this does not happen, then the socket is not receiving any current.
Because of the high response threshold, these devices are not suitable for more precise “probing. It should be noted that the stylus of the indicator necessarily must be applied only to one of the core wires of the cable or contacts, as is unacceptable between a phase and zero short circuit.
Using an indicator with an LED
As already described above, LED screwdrivers can support non-contact testing mode. This means that the person who performs the test does not have to short-circuit the electrical circuit with his finger inside the device. This highly sensitive mode makes it very convenient and quick to find hidden wiring in frameworks and walls, to determine the presence of voltage on electrical components or cables.
It is only necessary to bring the “heel” to the tested object. a part of the construction, where the finger is put during the contact test. And often it is not enough to apply the contact to the wire, but only bring it to him. the sensitivity of the device is enough to light up the LED. When searching for phase in outlets, proceed in the same way as described in the example with the simple tester.
The non-contact version of the test has the slight disadvantage that the screwdriver can respond to a tip and indicate voltage even during an open circuit. LED indicators have significant advantages over simpler models. a brighter glow, and you can work with voltages under 60V. Radiation from a neon bulb can be simply unnoticeable when used outdoors or in a well-lit room. you have to dim the handle to tell if it’s lit or not.
The principle of universal testers
Universal testers on the principle of application and action do not differ much from the devices previously described. However, they are less like a classic screwdriver and more like an electronic thermometer. The most advanced devices have a digital display that shows the voltage. This feature is quite useful, but raises the price of the product to the point where a full multimeter would be a great alternative for the money.
In addition to the display all universal testers have a contact pad for finger-zeroing the circuit and toggle switch mode of operation. On the toggle switch are these modes:
- H. non-contact high-sensitivity mode. Needed for tracing hidden wiring routes.
- L. no-contact mode. In this case, the indicator beeps or lights during the response to an electric field (the contact part is brought to the object under test).
- O. contact mode. Works as with simple devices: finger on the contact pad, stylus on the conductive element.
Two test methods
Indicator screwdriver was originally designed only to find life-threatening voltages on live circuits. This function is present in all modern indicators, but is used differently depending on the type. Let’s look at how to use a screwdriver to determine the phase and continuity of some devices.
1) The contact method
The contact method means touching the conductive parts with the sting of the screwdriver. It is available for all kinds of indicators. However, there is a significant difference between determining phase and zero with a passive-action screwdriver and other indicators.
With a passive screwdriver, the tip (stinger) is inserted into e.g. one of the sockets, while a second spring-loaded contact is pressed in the end of the housing.
A closed circuit is created: socket clamp. screwdriver tip. resistor. neon bulb. contact on the end of the housing. person acting as a capacitor. If you hit the phase terminal, the light bulb will turn on, if not, it won’t.
Other types use a built-in power supply to ignite the indicator, and the screwdriver sting is connected to a key made on a transistor.
If there is voltage on the tested terminal, the transistor opens and the LED lights up. In this case, touching the second contact on the screwdriver is not necessary. Otherwise, these models of indicator screwdrivers will “glow” On both phase and zero.
2) Non-contact method
This is not a function of the passive indicator. This way, without touching the bare part of the conductor, you can determine if there is current in it. How to use the indicator screwdriver in this case? Because the measurement is made through the insulation, the sensitivity of the device must be higher. To do this, touch the touch pad on the screwdriver handle.
As already mentioned, the human body is part of a kind of capacitor, through which some current flows. The sensor pad is connected to the gate of the transistor (the control element), and the circuit is designed so that when more potential than a human is present at the tip of the screwdriver, the transistor opens and the indicator lights up.
If there is voltage in the wire, magnetic waves form around it, inducing an EMF in the screwdriver’s core. This charge is enough to open the transistor. If the wire is hidden deep under the plaster, you can increase the EMF by attaching a piece of wire 10-15 cm long to the tip of the screwdriver.
Check continuity of fuses, diodes, light bulbs
One contact on an incandescent bulb, fuse, or diode is touched by hand, and the other is touched by the stylus of a screwdriver. Then its contact on the handle is pressed. If the diode lights up, the device is intact.