Connecting a screwdriver to the laptop power supply. How to convert a cordless screwdriver

Many home craftsmen are interested in the question of how to convert a cordless screwdriver into a corded one. This is due to the fact that many people use battery-powered models. But the battery has a limited shelf life, it quickly breaks down and the tool stops working. Buy new battery for a cordless screwdriver it is expensive, since its cost is more than half the cost of the tool itself. And then the idea arises of converting such a tool into a network one so that it can work from a 220 V network.

Why does this problem occur?

After a certain service life, the battery begins to spontaneously discharge, this leads to its gradual destruction, this process is irreversible. Once such a battery fails, it cannot be repaired; it must be replaced with a new one. In addition to the fact that the cost of a new battery is high, you can only buy a high-quality battery from official dealers, and they are not available in all cities.

Modern craftsmen have found a rather simple and affordable way To solve this problem, they remake the screwdriver and ensure that it is powered not from a battery, but from the mains. Using this option provides a number of advantages:

The corded screwdriver does not require periodic battery charging.

1. You will have no downtime during operation, as there will be no need to periodically charge the battery.
2. The current strength will not drop, as happens when batteries are discharged, therefore the torque of the screwdriver will be constant.
3. If you do not use the tool for a long time, they will not decrease specifications batteries, since there is simply none, because the screwdriver now works from the mains.

You can do this work yourself, there is nothing complicated about it. You must have basic skills in performing similar work and the necessary components. In this case, you can make a corded screwdriver from a battery-powered one yourself.

To complete the job you will need:

• old battery from the specified model;
• Charger;
• cable of the required length;
• soldering iron;
• solder;
• insulating tape.

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Carrying out refurbishment work

You will need a working charger, to the terminals of which you need to solder the cable cores. If they are copper or brass, then it will be possible to solder only after pre-treatment acid, after which they are well fixed. You can purchase special solder, but it will be more expensive.

Then the other ends of the wire must be soldered to the contacts of the screwdriver. To make this process easier, you can use an old non-working battery from this model of screwdriver. First, we need to disassemble the battery and clean the middle, since we only need its body.

When disassembling the battery, be careful because... its contents contain harmful substances. It is best to use hand and respiratory protection.

A soldering iron is needed to convert a cordless screwdriver into a corded one.

After cleaning the case, it is washed, for which a weak alkaline solution is used, which must be completely dry. The ends of the cable must be soldered to the contacts inside the battery case, and do not forget to maintain the polarity.

If you reverse the polarity, the working tool will rotate in the opposite direction, then you will need to get used to this and use reverse in the opposite position. Or you will have to redo all the manipulations to convert a cordless screwdriver into a mains one.

Before soldering the wire to the battery case, you need to make a hole in its lower part and thread the wire into it. The wire must be firmly secured in this place so as not to tear it out during work.

After completing the above work, the body can be assembled. Just be sure to add a counterweight inside that matches the weight of the battery. For such tools, the center of gravity is in the handle; if this is disturbed, it will be inconvenient to work. This design increases the load on the hand, but reduces the load on the hand. This will cause you to be very tired, because working with such a tool will be inconvenient.

It is best to use rubber as a counterweight; it will not only act as a counterweight, but also act as additional insulation. You need to cut the rubber a little larger, then it will fit snugly in the body and not dangle during operation.

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Alternative methods

Old inverter welding can be used as a power supply.

You can use a car battery as a battery, but if the voltage is the same, the current strengths will be different. This will lead to rapid overheating of the screwdriver motor. This solution is suitable for short-term work away from the mains. In this case, the cable is connected not to the power supply, but to the terminals of the car battery.

You can make a portable power supply, for which you use a transformer with the necessary parameters and a rectifier. It will be difficult to make a transformer yourself without the appropriate skills, but it can be selected from some other equipment, then all that remains is to make a rectifier.

To create a rectifier, you will need to make a diode bridge from semiconductor diodes; its parameters are selected for a specific screwdriver.

A good solution would be to use a power supply from a computer; at its output you can get the required current. The presence of a cooling system makes such a unit reliable and durable. Refinement of this device will consist of creating an insulating housing and grounding.

Old inverter welding can be used as a power supply. True, it does not have the same current strength, so improvements will have to be made. All components are left, only the secondary winding is added, this way you can achieve the required performance. Here you need to have special knowledge in order to calculate everything correctly.

It so happened that for a long time I had a rather poor Stern screwdriver lying around in my household. One speed, no power, the battery died a long time ago. It lay there and lay there, long ago replaced by a normal instrument, but then suddenly it came to life with a second life. I recently found it useful, so I’m telling you the story of the second birth of a screwdriver.

So, I’ll tell you about how 10 years ago I modified a screwdriver to work on a 220-volt network.

Advantages of converting a screwdriver from the mains:

1. An old screwdriver, for which you can no longer buy a battery, gets new life
2. There is no need to monitor the battery charge and recharge it. He lies in his closet and doesn’t ask to eat.

Disadvantages of a corded screwdriver:

1. I was unable to immediately find the suitable parts to assemble a sufficiently powerful power source. The screwdriver has lost power.
2. We are dependent on the electrical network.

Power supply for screwdriver

Since the native power supply of the screwdriver is 14.4 volts, the only suitable transformers we found were the rod type. It was previously glued to a sealant in some kind of power supply.

The conversion involved finding an old battery and converting it into a container for the power supply. Since the battery was still more or less alive at that time, I did not disassemble it and the network version turned out to be a bonus to the main one.

First, I pulled out the old nickel-cadmium batteries from the case, found a transformer, a diode bridge and a capacitor from those that were at hand, soldered them according to the simplest scheme, and stuffed them into the case. If you are planning to make a similar power supply, do not forget to install a fuse!

The Internet is full of creepy videos about what power supplies are made of, so I found one useful one, where current and voltage are measured in different modes when powered from different sources.

What did I get as a result? Fully working screwdriver, convenient, practical. Due to the fact that I did not optimize the power supply, I lost a little power.

I can’t give information on the transformer - there are no markings. If necessary, I can measure voltage and current. Although, as I already said, my power supply does not provide maximum power.

Finally, I began to implement my long-standing idea, namely, to provide power for the screwdriver from a 220-volt network. Undoubtedly, some of you also have a screwdriver with a worn-out, unusable battery that no longer takes a charge. I had two copies at my disposal.

The first (black) operating voltage is 18 Volts. This is what I initially wanted to power from the network, because... It fits comfortably in the hand and is quite powerful. But the button is missing. Perhaps in the future I will cut off the handle and make it into something like a drill. The second copy is designed for 12 Volts. Served for quite a long time. Of course, you can purchase a new battery or, in extreme cases, replace the banks. But still, you want to always have a ready-made tool at hand, especially since an electric drill is not always convenient to use because she's heavy. A power transformer will help us realize this idea.

A step-down transformer TS-250-36 was used. "250" is its rated power, and the number 36 means that the output voltage will be 36 V. It has an O-shaped magnetic circuit. Its windings are arranged in such a way that half of the primary is wound on the left, the second half on the right side. The secondary winding, which is located on top of the primary, is wound in a similar way.
It is not difficult to distinguish the windings from each other in a step-down transformer, because the secondary one is made of thicker wire, and the one to which it is fed mains voltage from thinner wire. This is due to the fact that a smaller current flows through it.

The windings have a symmetrical arrangement and two halves of 18 volts are connected by wire (the connection point is clearly visible in the bottom photo). I'll use one half.

But before you rewind the transformer, you need to take measurements. I urge you to be careful when working with current, do not touch live parts, and always check that the measurement limit on the multimeter is set correctly.

On the right, the voltage is measured on half of the secondary winding. As you can see, the voltage slightly exceeds the rated values, because there is no load connected here.

So I separated one half and now we begin to disassemble the transformer. There was a large amount of paraffin between the layers of paper.

The secondary winding in my case is wound in two layers, separated by a layer of paper. To reduce the secondary voltage from 18 volts, almost half of the turns had to be removed.

When determining the required voltage, you need to take into account that after the transformer there will be a diode bridge, which will reduce the voltage by about a couple of volts. But adding a smoothing capacitor will cause the voltage to increase by about 1.4 times. Those. in the absence of load, the rectified voltage on the capacitor will be equal to the amplitude value.

As the secondary unwinds, we take measurements. Soon, I settled on a value of 11.2 Volts, because... I was afraid of drawdown when connecting the load.

Once the transformer is prepared (although some may use a ready-made one with the required parameters), now it's time to get acquainted with the circuit.

A diode bridge (VDS) must be soldered to the output of the transformer to convert the alternating current into a pulsating direct current.
The diode bridge can be assembled from separate diodes or used ready-made. When selecting it, you should take into account how many amperes your screwdriver consumes (choose the bridge with a reserve).

We solder the wires from the secondary winding to the terminals of the diode bridge, where the letters AC (alternating current) are.

Well, after the bridge you need to solder a capacitor to smooth out the ripples. Its voltage must exceed the supply voltage of the screwdriver at least twice. And the capacitance is from 470 µF to 2200 µF.

If desired, a switch and fuse can be added to the circuit in front of the transformer.

So, after connecting the circuit, I took measurements. The idle voltage at the output of the power supply (when no load is connected) is 15 volts. When starting the screwdriver, it drops to 11.5 volts, which is normal, so it’s okay. A fully charged new battery produced 13 volts.

This is what the instrument looks like from the inside. Here you can find the limit parameters of the button, and you can also notice that the motor is controlled by a powerful field-effect transistor.

To make it easier to connect to the power supply, I disassembled the battery. We will need contacts from him.
This part needs to be tinned. I did my soldering using rosin, but in some cases you may need flux for soldering aluminum.

Of course, when soldering wires from the power supply, do not forget about the polarity; it is usually indicated on the battery case.
The compartment became very light. The wire was sealed with hot glue.

Tests showed that the screwdriver coped with the tasks when operating from the power supply.

This article has a video that shows in detail the process of creating a power supply, rewinding the transformer, connecting and testing.

List of radioelements

Designation	Type	Denomination	Quantity	Note	Shop	My notepad
T	A step-down transformer	Select by voltage	1			To notepad
VDS	Diode rectifier assembly	PBL405	1	Better more powerful		To notepad
WITH	Electrolytic capacitor	470...2200 µF	1	Not less than 50V

The question of how to convert a cordless screwdriver into a corded one often arises when the tool breaks down and the battery can no longer be repaired. A new power source is often not much cheaper than a new tool.

Features of the Network Tool

The only downside to using corded screwdriver consists in connecting it to an outlet. But if you work mainly indoors, then this minus is not a problem for you. There are many more advantages, because there will be no downtime during the work, the current strength remains at a stable level.

In order to make changes to the design, you need to study the parameters of the tool in the passport or on the sticker on the body. The voltage indicator and the average current value are important.

Source options

Experts offer several ways to convert a cordless screwdriver into a corded one:
The first option is to use a comprehensive charger device. This method is characterized by ease of work process. If the charger is suitable, there is no need to select voltage. No need to interfere with electrical diagram, which also simplifies the procedure. The disadvantages include the large parameters of the charger.

The next method is to use a ready-made block that replaces the old one. The procedure is simple, even a novice master can handle it. This engineering solution allows you to make a screwdriver from the network. In this case, there are no losses in the cord with a low voltage rating. Similar to the previous option, there is no need to interfere with the electrical circuit. The disadvantages of the application include the need for a ready-made unit with the appropriate voltage. It can also overheat in the battery case. Because of this, it is necessary to take frequent breaks from work.

Placed in an old battery homemade block. This is a rather attractive engineering solution. There are no losses in the low voltage cord. The user may not interfere with the electrical circuit. This method requires certain soldering and assembly skills, and knowledge of methods for debugging electrical circuits will be a plus, because in the process you will need to select a circuit and find the appropriate radio components.

A simple option for using an external unit. Experience in disassembling and connecting the device to the circuit is required. In addition, it takes up space, and you will need to select a suitable case.

The next option is a computer power supply with ratings starting from 300 W. It's easy to remake. To implement this option, experience is required in connecting the device to the circuit. The disadvantages include the fact that the block also takes up extra space.

Connection

The charger cable must be longer than 1 meter. The cross-sectional indicator should be more than 2.5 square meters. mm.

The procedure requires the following actions:

• Solder and attach 2 wires to the terminals of the device using clamps.
• Disassemble the old battery, then remove the previously dead cells.
• Next, drill a through hole intended for the cord, thread it through, and seal the connection using electrical tape or heat-shrink tubing. This will prevent the cord from coming out.

Such alterations disrupt the weight distribution of the device. To restore balance, a weight is placed in the body. A dense piece of wood or rubber is suitable for these purposes.

• Next, solder the cable to the terminals from the old battery.
• After this you need to assemble the body.

The product assembled in this way is tested during operation.

Installation

To mount the finished unit in an old battery, it is recommended to make holes in the case, since it is poorly cooled because it is completely closed, and this can lead to negative consequences.

The installation procedure is as follows:

1. To begin with, the block is disassembled. It is necessary to find and remove non-working elements.
2. Then it needs to be installed by connecting the high voltage level contacts, as well as the low voltage terminals.
3. Then you need to assemble and close the block.
4. The battery is installed in the device.
5. At the end, the power supply plug is plugged into the socket, after which the updated network tool is checked.

Homemade instrument

You can assemble the block yourself. Soldering and connection are carried out on a de-energized device.

First you need to disassemble the old case and remove the dead batteries from the inside. Install the electrical circuit elements onto the circuit board. The next step is to solder the contacts.

Install the assembled board into the case. Use a tester to check for voltage. A low voltage wire is connected to the terminals, after which the housing can be assembled. Connect the device to the network, then check its functionality.

Step by step work

When modifying, disassemble the device body, and then remove the electrical circuit. It is best if you have experience in similar work and an understanding of the features of the process. It is necessary to remember the sequence of disassembly and assembly.

The term "diode bridge" refers to an electrical device that is designed to convert alternating current half-wave with a pulsating character.

Disassemble the tool and then look inside for the motor power wires. You need to install a connector designed specifically for the power supply, then solder it, securing the cords with hot glue. Find a suitable block, for example from a laptop. Select a connector with a low voltage value for it. After this, you can proceed to the connection. Finally, check if it works.

Autonomy

If you work indoors without electrical energy, and the batteries have deteriorated, you need to power the screwdriver.

This can be done in several ways:

• replacing old batteries inside the device with new ones;
• connection to a car battery;
• connecting the instrument to another device. In particular, you can use an uninterruptible power supply.

Replacing Old Components

To carry out this procedure, you will need to open the battery, removing non-working elements. Then new ones are installed inside and soldered. Close the lid and put the battery back in place. In some cases, simply charging the battery is enough, for which you need to use special chargers.

There is one more effective option– connection to a car battery. The screwdriver is disassembled, then the corresponding contacts are found. After assembling the tool, it is important not to forget to test it for functionality.

• The unit must be periodically cleaned of dust.
• It is necessary to give the screwdriver time to take a break after 20 minutes continuous operation.
• Secure the electrical cord to your hand so that it does not interfere with the work process.
• Do not use extension cords.

If you follow these simple rules, you can extend the life of your instrument. In this case, its mobility is lost, but the need for constant recharging disappears. Remaking a screwdriver gives the device new life. This device will last longer. The only drawback is the dependence on the outlet and the length of the cord.

A screwdriver is a tool designed for tightening screws and drilling small-diameter holes. There are mains ones, powered by 220V mains, and rechargeable ones, with two replaceable batteries.

If the battery in such devices fails, there are three options:

• replacing the battery is expensive; in a budget-class device, the price of the kit is close to the cost of a new device;
• repair is not always possible, and in some cases its cost is comparable to the cost of new batteries;
• Converting a cordless screwdriver to a corded one.

This article talks about how to power a screwdriver from a 220V network, or how to turn a cordless screwdriver into a network one.

Screwdriver device

This mechanism consists of the following parts:

• Electric motor direct current. It has the shape of a cylinder; in the housing, instead of the excitation winding, there are permanent magnets. This simplifies the design and provides sufficient torque at low speeds. The drive (sun) gear of the planetary gearbox is mounted on the electric motor shaft;
• Reversible speed controller. The adjustment circuit is assembled on a PWM controller and a field-effect transistor. Reversing is carried out by switching the polarity of the power connection to the motor brushes;
• Planetary reductor. Made in a separate building. It got its name due to its resemblance to solar system. Consists of a ring gear, a central (sun) gear, satellites and a carrier. The ring gear transmits force through the spring-loaded balls of the load regulator. There are models with two-speed gearboxes. Increased speed is activated when using the device as a drill;
• Rotation force limitation mechanism. Serves to limit the force when tightening screws. Transmits torque through balls pressed by an adjustable spring;
• Removable battery. Consists of individual elements in one housing. Voltage in different models ranges from 9 to 18 volts.

Screwdriver battery design

The design of the battery does not depend on the brand. In all devices, the battery design is similar and different. appearance, housing and contacts.

The housing contains several elements connected in series. Their number depends on the voltage of each element and the battery as a whole. When using the most common nickel-cadmium elements with a voltage of 1.2V, 10 pcs are needed to power a device with a nominal value of 12V. Battery capacity is indicated in ampere hours.

Interesting. With a series connection, the output voltage increases, but the capacitance does not change and is equal to the capacitance of the individual elements.

Types of battery cells

These devices use elements different types and voltages, each of which has its own advantages and disadvantages.

The most common are nickel-cadmium (Ni – Cd) with a voltage of 1.2V.

Advantages:

• low price;
• stored in a discharged state.

Flaws:

• have a memory effect;
• high self-discharge;
• small capacity;
• small number of charge/discharge cycles.

More advanced nickel-metal hydride (Ni-MH) voltages are 1.2V.

Advantages:

• less memory effect and self-discharge;
• large capacity and number of charge/discharge cycles.

Flaws:

• higher price;
• poorly tolerated low temperatures and storage in a discharged state.

The most advanced lithium-ion (Li-Ion) voltage 3.6V.

Advantages:

• no memory effect;
• very low self-discharge current;
• high specific capacity, allowing to reduce the weight and dimensions of the device;
• the number of charge/discharge cycles is many times higher than other types of batteries.

Flaws:

• high price;
• loss of capacity three years after manufacture.

Converting a screwdriver to power from a 220V network

If the battery fails and it cannot be repaired, the only way out is to convert the cordless screwdriver into a mains one.

In this case, the power of the power supply must exceed the power of the engine, taking into account possible overloads at the moment of completion of tightening. It is not indicated in the device passport, but this parameter is written on the body of the electric motor, or it can be calculated by connecting the device to a source DC voltage through an ammeter. For a 70W motor, a 120W power supply is sufficient.

Important! The charger's power is insufficient to operate it. When converting a cordless screwdriver into a mains-powered one for 220 volts, you must use a different power supply.

Using an external power supply

The external power supply device is larger in size than the built-in one, but in any case, if you power the screwdriver from the mains, the tool will be “tied” to the socket by a wire.

The current coming from the power supply reaches 10-15A, so the cable cross-section must be at least 1mm².

Interesting. The screwdriver can be powered from an old car battery or from a car through the cigarette lighter socket.

Computer power supply

The simplest and cheapest option is to use a power supply from an old computer with a power of at least 300W and a current of 15A.

In old units there was a switch, in modern ones - to turn it on you need to short-circuit the wires going to the device. The color of these wires depends on the model. This can be found on the Internet or by selection.

The 12V output is located in a four-pin connector: black “–”, yellow “+”.

Such devices have a built-in fan, so when making a housing for it, it is necessary to make holes or install it with the fan facing outward. It's best to simply hide the excess wires inside the case.

Important! A 14.4 or 18 volt screwdriver will operate at reduced power.

Car battery charger

The requirements for this device are the same as when using a computer unit.

If so, it is advisable to use a device with a built-in voltmeter and voltage regulation. Some models have a current-limiting resistor installed inside. It needs to be short-circuited.

How to make a homemade power supply

In addition to the purchased one, you can make your own power supply. To do this, you need a 160W transformer, the kind that was installed in tube TVs.

First of all, it is necessary to determine the required number of turns. The procedure is as follows:

• disassemble the transformer;
• unwind all secondary windings from the reel;
• wind 10 turns of wire;
• assemble a transformer;
• connect to 220V network;
• measure the voltage on the secondary winding;
• divide the number of turns (in this case 10) by the measured voltage.

The resulting value is multiplied by the supply voltage of the screwdriver and the required number of turns is obtained.

Attention! The number of turns per volt can be obtained by measuring the voltage and counting the turns in the secondary winding.

The step-down winding is wound with a wire with a cross-section of 1 mm² to reduce the voltage drop in the transformer.

The output of the transformer is alternating voltage, but the device requires constant voltage, so a diode bridge is installed in addition to the transformer. It is assembled from diodes on radiators with a voltage of more than 20V and a current of 10A. It is mounted together with a transformer or in a battery case from which the elements have been removed.

Built-in battery power supply in case

If you have the desire, time and “direct” hands, the unit can be placed in the battery case. To do this, a ready-made device with the appropriate parameters is purchased, removed from its housing and mounted in the battery housing. The terminals are soldered with a wire with a cross-section of at least 1 mm² to the battery terminals, and the power cord is replaced with a longer one.

Important! If there were ventilation holes in the power supply case, then it is necessary to make similar ones in the new design.

Assembling a working battery from two that have lost capacity

From two faulty devices you can assemble one that is suitable for use.

Important! By connecting a power supply to the body of the faulty battery, a second repaired one will provide mobility when performing small amounts of work.

Finding faulty elements

The battery is assembled from individual elements. They do not fail at the same time, but even one faulty element impairs the performance of the entire battery.

To determine the parts that have lost capacity, you must:

• charge the battery;
• work until power loss;
• disassemble the battery;
• measure the voltage on each element separately.

Batteries on which the voltage is noticeably less than others or absent altogether must be replaced.

Battery repair

After identifying and removing the faulty parts, the remaining parts are assembled into a device suitable for further use. The connection is made by soldering, wires with a cross-section of 1.5 mm² or a strip similar to the one with which the parts were connected before.

If there is an insufficient number of serviceable elements, we purchase the missing ones or convert the instrument to a 220-volt mains power supply.

Knowing how to convert a cordless screwdriver into a corded one with your own hands will help you save money and not have to purchase a new device.

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