Converting an electric screwdriver for mains power
One of the most common causes of failure of an electric screwdriver, is battery wear, that is, the moment when the battery ceases to take the charge required to operate the tool. This always happens unexpectedly and always causes confusion: all the assemblies and mechanisms are functional, but it is impossible to achieve a result because of the lack of power. Repairing the battery, as well as the purchase of a new one is not the cheapest way out. But, it is possible to convert the portable model to a network model, working from a 220 V source, and return it to working condition. About how to do it, we will talk in this article.
A prerequisite for the successful reconstruction of an old electric screwdriver is the proper functioning of its main parts: the motor, the gearbox, the starter button, and the clamping jaw. Only the power element is subject to modification, so the rest of the “stuffing” must be in working condition.
Of course, the tool will lose its major advantage of mobility as a result of these structural modifications. It will depend entirely on the availability of a nearby power point with 220 volts. But it will keep working for a long time and even have some advantages:
- cost savings;
- no need for periodic recharging;
- no functionality loss after a long period of inactivity.
One way to solve the power supply problem is to use extension cords, but this option is not always available. Nevertheless, the power tool will remain useful and can serve in the home workshop.
Different devices used when converting an electric screwdriver
The best way to turn a cordless tool into a corded tool is to use a remote power supply. Its main purpose is to convert 220 volts to an acceptable voltage for the product (12, 14, 18 volts). It must correspond to the rated voltage for which the consumer is designed.
Tip: The amount of current coming out of the power supply should be about the same as the value listed in the power supply’s data sheet. Otherwise, the tool may not produce the power required for operation.
Among the devices most commonly used in screwdriver remodeling are the following:
- Power supplies from laptops or personal computers;
- car chargers;
- Professional power supplies for screwdrivers.
On the peculiarities of the use of these products, are outlined in the following sections of the article.
Other ways to upgrade
Radio amateurs offer many options for upgrading tools. Some of them are very simple and are reduced to the use of ready-made power supply units, while others require knowledge in the field of electrical engineering and give the device a universal. Classification of methods:
- Power Adapter for Laptop.
- Connecting a computer switching power supply (power supply).
- Using a 12-volt car battery.
- Assembling a homemade power supply.
Using a laptop charger is the best solution. In addition, it is necessary to know the parameters of an electric screwdriver and charger (there are 12 V and 19 V), as well as to take into account the dimensions of the latter (for installation in the battery compartment). You need to solder the output of the laptop power adapter, to the terminals of which the battery is connected.
When using a switching power supply (power from 350 watts and above) for the PC (form factor AT) is necessary to find the voltage 12 V at the connectors that power the hard drive or CD-ROM drive. Take out the wires, and the rest of the wires carefully cut and insulated. You can assemble the case for the PSU, which will allow you to get current up to 16A. In addition, it is necessary to remove the start-up protection. To do this, connect the green wire to the black wire from this connector. These two methods are very simple and do not require additional description.
The car battery is the best source of electrical power. Nothing has changed when upgrading the model other than connecting a different battery. A significant disadvantage is its weight. In addition, you need to assemble a charger or buy one in a specialized store.
Building your own PSU is the best solution for those who maintain quality. The previous options are good, but do not allow for flexibility. For example, they are applicable only for 12 V screwdrivers, not 18 V. There are chargers that are designed for 19 volts. Getting 18V is achieved by connecting batteries in series, e.g. 12V and 6V. Note that the characteristics of the batteries should differ only in terms of voltage. This is why it is often necessary to build a power supply yourself.
Schematics and description
Option of assembling PSU by yourself should be made on the condition of knowledge in the field of radio engineering. In addition, before assembling you need to think carefully about everything, find a case for mounting and the appropriate radio components.
A simple PSU option
A simple circuit 1 PSU (electric screwdriver from 220 volts), consisting of a power transformer (diode bridge input), rectifier and capacitor filter.
Scheme 1. Power supply for an electric screwdriver 18 V
The transformer must be chosen with a capacity of 300 watts or more, the voltage on the II winding must be in the range from 20 to 24 V and the current value over 15 A. For the diode bridge use powerful diodes, matched to the current of the secondary winding. It will be more difficult to select the appropriate power supply for an electric screwdriver. At the output of the rectifier you must put a capacitor with the capacity of 2000 uF (you can limit the capacitance to 470) and voltage of 25 V or higher. Parts must be selected with a reserve of current and voltage. All radio elements are mounted on a gethinax board, which is attached to the housing.
Universal power adapter
The suggested variant of universal PSU has excellent characteristics and can handle a load current of up to 10A. The output voltage is 18 V, although you can make calculations and make a power supply for an electric screwdriver 12 V. This PSU can be used as a battery charger (battery charger) and as a backup power source when mains power is off (Scheme 2).
The adapter is assembled on the voltage regulator, consisting of a transistor VT3 and VD2-VD5 (Stabilizators). Using the toggle switch SB1 turns on the power and closes its contacts relay K1. Power goes to the transformer, which converts the AC current to the required rating. The output current from the transformer flows to the rectifier. Then the rectified voltage is fed to the regulator. There is also a current amplifier in the circuit, assembled on transistors VT1 and VT2. To this amplifier the load is connected. The battery charging mode (backup power supply) is realized through VD6 and the limiter in the form of resistor R4. By means of SB2 it is possible to switch off the charging of the battery.
Scheme 2. Universal power supply for an electric screwdriver and battery charging
In the absence of supply voltage of 220 V, the relay is de-energized and the voltage from the battery is fed to other contacts of the relay (directly from the battery). Fuses are used for protection against short-circuit currents and overloads. This system can be used without a backup power supply. No further adjustments are required.
The list of parts is shown in the corresponding schematic 2, however substitutes with counterparts are possible, e.g:
- VT1 and VT2 can be replaced with KT808 or KT819 with the same parameters. The transistors require cooling and a heatsink is therefore mandatory. The transistors can be sealed with thermal paste to improve heat dissipation. Analogous to VT3 are KT815 or KT817. Any alpha-numerical designation is acceptable.
- Transformer should be used with output power more than 150 W and with voltage under load on the II winding of 14-16 V. Battery is standard 12V.
- AC relay K1 must be used for voltages of 220 V and currents of 3 A.
- FU1 should be 3A, FU2 should be 10A.
- Rectifier is already used (KTs405A, in extreme case. KTs407A) or assembled on the diodes D231 and D242 (any letter index). The diode VD6 can be replaced with the similar one, guided by the reference book or Internet.
- Stabilitrons are desirable to leave the same: the output voltage parameters depend on them, though a series connection to the necessary U.
- The capacitors can be replaced with any analogues according to the reference documents. Consider the U in the circuit, to which the capacitor is connected.
- Resistors R2 and R3 (MLT-0,5), R1 and R4 (type PEV-10 or VZR-10).
After assembling the device is assembled and brought to the appropriate appearance, the design is chosen by yourself.
12 V adapter
The adapter is assembled on the chip 7912 and is a linear regulator. The transistor increases the power of the PSU (Diagram 3). It is possible to power an electric screwdriver for 18 V with this DIY, for which you need to calculate the transformer.
Scheme 3. Power supply for electric screwdriver 12 V
The secondary power supply is a transformer, the output of which is 16 V (for model with 12 V DC power supply) or 22 V (for 18 V electric screwdriver power supply). Rectifier is assembled from ordinary diodes with reverse voltage over 50 V (it is possible to use ready-made variants). The smoothing filter is a high capacity capacitor of about 10000 uF, but the greater the value, the better.
The microcircuit must be purchased at a specialized hardware store. In addition the circuit uses LEDs, so that you can make diagnostics when the power supply fails. Radio element 2N3055 is a p-n-p structure transistor and it can be replaced by any (analog must be chosen from reference books with a voltage of about 50V and current over 5A). It is possible to use LUT to make the circuit board. There is a detailed description on the internet about how to make a printed circuit board using laser cutting technology (LUT).
Adjustable modification
Regulated BP is very user-friendly and versatile. Thanks to the adjustable voltage values it is possible to power any kind of equipment, to use it for charging the battery. The basic element is a microcircuit type LM317. Amplification is done with the help of two transistors like 2N3055, but you can use a more powerful, because the power supply increases and allows you to get current up to 20A. Transistors are mounted on a heat sink, and it is desirable to apply in the design also a fan for cooling (cooler from a personal computer at 12 V).
-
A double winding transformer for 15V and 10Amp current.
- Diodes D1-D4 (diode bridge): MR750 or other analog.
- Fuse links for 1 A and 10 A. The second parameter is chosen according to the real load (current consumption).
- Resistors: R1 (2.2k for 2.5W), R2 (240), R3 and R4 (0.1 for 10W), R7 (6.8k), R8 (10k), R9 (47 for 0.5W), R10 (8.2k).
- Capacitors: C1, C7 and C9 (47n), C11 (22n), C2 (4700μ at 50V), C3 and C5 (10μ at 50V), C4 and C6 (100n), C8 (330μ at 50V), C10 (1μ at 25V).
- Diodes (you can use analogs): D5 (1N4148, 1N4448 or 1N4151), D6 (1N4001), D10 (1N5401), D7, D8 and D9 (1N4001).
- Circuit: LM317.
- Transistors: 2N3055.
- Resistors: P1 (5k), P2 (47 or 230 watt), P3 (10k).
How to convert a cordless screwdriver to run on 220 volts
Craftsmen have devised several ways to convert the screwdriver for use with electricity. They are all about providing the motor with the voltage it needs, through an intermediate source or converter.
Table: Power supply options for a power screwdriver
- An uncomplicated conversion.
- Uses your existing battery charger.
- No need to adjust the voltage of the power supply.
- No need to tamper with the electrical circuitry of the screwdriver.
- Easy remodel.
- Nice engineering. only the power cord comes out of the screwdriver.
- No loss in low-voltage cable.
- No need to interfere with the electric circuit of the screwdriver.
- Search for a compact power supply with the required voltage.
- Power supply gets warm in closed housing, you need to take breaks in your work.
- Nice engineering. only the power cord comes out of the screwdriver.
- No loss in low-voltage cable.
- No need to tamper with the electric circuitry of the screwdriver.
- You need to pick up a circuit and find radio components.
- The wizard must have experience in soldering, assembling and debugging electrical circuits.
- You need to disassemble the screwdriver and connect to its circuitry.
- Power supply takes up space on your table.
- Need to find a suitable power supply.
- Easy to rebuild.
- Computer power supply easy to find.
- Any power supply of 300 watts and more will do.
- Requires disassembly of screwdriver and connection to its circuitry.
- Power supply takes up a lot of space on the table.
Features of an electric screwdriver
An electric screwdriver is a hand-held device for working with various fasteners. It is used to unscrew or screw in screws, dowels, self-drilling screws and other fasteners, and in some cases it also allows you to drill holes. This device runs on electricity, has a special chuck or bit holder (only for bits) into which you can insert a drill bit or a bit that matches the shape of the fastener (such as a Phillips, hexagonal bit, etc.).д.).
- mains-powered. respectively, has a mains cable and is spatially limited in use by the length of the wire (it can only be used if there is a socket or extension cord and cannot be used if the electricity is cut off);
- battery-powered. runs on a battery-accumulator, can be used where there are no outlets, but it can be used only until the battery is depleted;
- from a compressor. the pneumatic version, which is turned on by the supply of air.
How an electric screwdriver is designed The structural components of an electric screwdriver:
- motor that makes the spindle rotate;
- the spindle on which the bit chuck is mounted;
- chuck, which allows you to fix the right bit;
- Gearbox that transmits the rotation from the motor to the spindle;
- the rotation speed regulator;
- Buttons to turn on, switch the direction of rotation (reverse);
- Battery. the power source (only in cordless screwdrivers).
The body of the product in most cases is made of plastic. due to this the production of devices was made cheaper at one time. There are also metal versions. they are more reliable and durable than plastic ones, but they are much more expensive.
Also for your information! The very first example of an electric screwdriver appeared in 1982 and was presented at an exhibition in the GDR.
Now you know about the construction of an electric screwdriver. This information will come in handy if you decide to convert your cordless version to a corded version, since you will still need to disassemble the device. It is not superfluous to know where and what this device has.
There are many ways to power an electric screwdriver from the mains
How to convert cordless electric screwdriver to 220 V
Over time, the battery of a cordless electric screwdriver wears out, so it has to be charged more often and longer. In order not to change it, you can switch the tool to mains power, thus ensuring its uninterrupted operation. If you have a power supply you can do it in about half an hour.
Basic Materials:
To transfer power to the electric screwdriver from the battery to the mains, you need to get to its power contacts. To do this, you need to take apart the housing of the battery pack. The batteries present in it are removed.
Since the battery contacts remain on the removed batteries, it is necessary to refine the case in order to return them. To do this, I cut two short pipes from a 20-gauge polypropylene pipe. Their length must match the height of the battery pack removed. It is necessary that the pieces fit into the battery case of an electric screwdriver.
Most likely one of the edges of the tubes will have to be trimmed slightly, as it will rest against the protrusions on the cover.
Next, you need to remove the contact plates from the batteries and move them to the tubes. To ensure that they fit snugly, each tube should be wrapped with electrical tape, thus increasing the seating diameter. After that, a cable of a convenient length is soldered to the contacts, and they are finally attached to the tubes.
Now connect the cable from the electric screwdriver terminals to the power supply wire. Here it is important to observe the polarity. The plus side of the power supply must connect to the plus terminal and the minus side to the minus terminal. It’s best to solder the twist together for strength. It can be insulated with electrical tape or heat shrink.
Next, the contacts and tubes are inserted into the battery housing. To do this, a side opening is made right at the junction with the cover to introduce the wire. To prevent the tubes with contacts from shifting and falling out, everything is fixed with hot melt glue. For reliability, it can also be applied to the joint between the housing and the lid, so that it does not open.
Now when you plug the power supply into the socket, the electric screwdriver can work from the mains for as long as you want without recharging.
Converting a cordless screwdriver into a cordless screwdriver with my own hands
How to convert a cordless electric screwdriver to 220v? About a year ago I discovered that my Ryobi 18V tool battery had become unusable, and since I was working overseas, I had no way to get a new. So, I came up with a device to safely run my tools on AC power (household current) and stopped worrying about my tools stopping functioning on the way to work.
I have enjoyed all the benefits of battery-powered power tools They are handy, mobile, and often you can get a number of tools that run on the same battery. And then the inevitable happened. the diodes on the charger started flashing strangely, and the battery started discharging almost instantly.
I was faced with two options: throw away a few thousand on a new set of batteries, or try to rebuild them myself. None of these options appealed to me, and I didn’t have time to order parts from overseas. Like everyone else in my situation, for an alternative solution, I searched the Internet for information. I found some guys plugging car batteries into their drill, but I rejected that idea too. And then I came across the idea of using an old laptop power supply instead of batteries.
The voltage was right, but, alas, the power was too low. Even with 180W of power, the most powerful PC power supplies couldn’t provide enough current to overcome the starting current of my circular saw or angle grinder.
The way the PC power supply worked suited me, I just needed something more powerful. After a little research, I discovered that the power source for the laptop was what is called a “switching power supply”. It turns out that switching-mode power supplies are very common in the world, they are affordable and have a variety of voltage and power ratings In the end I chose a power supply AC / DC power 350 W, produced by a reputable company Meanwell with a range of DC voltage 15-18 volts.
Connecting a power source to a discharged battery is very simple and this manual describes the conversion of an electric screwdriver to mains with your own hands in detail.
Is it worth it to mains
Many might not understand why a tool should be mains powered. The truth is that the battery does run out of power over time and sooner or later the cell will need to be replaced. As practice has shown, it is expensive, and the selection of a quality part can take time and finances. If you convert an electric screwdriver to work on the mains, you can:
The latter depends on the charge of the battery. If mains-powered, the tool will have the same performance. The only disadvantage of mains operation is the dependence on the length of the cord. Therefore, in the design presented below will be considered a variant with a removable element.
Materials
Before proceeding to the task at hand, you need to look at whether everything is there to “upgrade” the tool. In the process, you will definitely need:
- Power supply from a computer;
- Electric screwdriver 12 V;
- A capacitor;
- A soldering iron;
- Drill;
- Duct tape;
- XT60 power plug;
- A 6 watt bulb or two 3 watt bulbs.
These tools and materials will help you convert your electric screwdriver to mains power without harming the tool. And the following will be considered a variant of the organization of a removable cord.
The mobility of the device
When converting cordless equipment to mains power, one of its main distinguishing features is lost. mobility. Therefore, if you decide to make a redesign of the screwdriver power supply, you need to determine exactly what device you want to use in the future.
There are two concepts for how to convert battery-type equipment to mains:
- Power supply (PSU) will be external. This version involves a separate device. But do not let this scare you, even a heavy and large rectifier can just be near the power socket. You will still be limited by the length of the power cable either to the outlet or to the power pack. According to Ohm’s law, reducing the voltage for the same power increases the amperage. That’s why the power cord of a 12-19 volt device should have a larger cross section than the 220 volt power cord.
- The power supply is built into the battery case. With such a device mobility is almost completely preserved, only the length of the mains cable can limit the movement of the operator. One problem may arise when it is necessary to install a high-power transformer in the battery housing of a screwdriver. But the modern radio industry allows to solve this problem, there are a large number of compact rectifiers in the radio equipment markets.
Each method has its supporters, as it has a certain set of characteristics.
Options for making a power supply
There are several options on how to convert a screwdriver to run on mains power. The task is to power the electric motor of the device with an intermediate source.
We use a laptop charger
To make a 12V power supply for a screwdriver with your own hands is possible, even without technical knowledge. It is only necessary to find an unnecessary charger from a laptop, which has specifications similar to the parameters for powering a screwdriver. The main thing that the output voltage corresponds to the sought (12-14 volts).
To achieve this goal, you must first disassemble the battery and remove the defective elements from there. Then follow these manipulations:
- Take the battery charger from a laptop.
- Cut off the output plug, stripping and tinning the ends of the wires.
- We solder the stripped wires to the battery input wires.
- Insulate the soldering points to avoid short circuits.
- We make a hole in the body, so as not to squeeze the wire, and make the assembly of the construction.
The base is a computer power supply
To make this device you need a block of A-format PC power supply. Т. It is not difficult to find it, it is an old model of the power supply, which is easy to buy at any radio parts market. It is important to know that you can use a block of 300-350W power with a current of 12 V at least 16 A.
The AT format blocks have these parameters. There is a power button on the case of this device, which is very handy when working. Inside there is a cooling fan and an overload protection circuit mounted.
The order of rebuilding the unit:
- Removing the housing cover B. П. Inside we will see a board with many wires going to the connectors, as well as a fan.
- The next step is to disable the power protection. You can find the green wire on the big square connector.
- Connect this wire with the black one from the same socket. You can make a jumper from another piece of wire, or you can just cut it short and leave it in the case.
Then find the smaller connector (MOLEX) in the output bundle and do the following with it:
- We leave the black and yellow wire and cut the other two short.
- For the convenience of the PSU location during operation, solder an extension wire to the black and yellow wires.
- Attach the other end of the extension cord to the terminals of the empty battery compartment. Make it by soldering, you can make a good twist, and you must strictly observe the polarity.
- Make a hole in the case, so as not to squeeze the wire during assembly. Your device is ready.
If you have the desire to ennoble your design, t. е. to hide it in another case, drill holes for air intake to prevent the PSU from overheating.
Power from the car charger
Having a car battery charger, it is pretty easy to make a device to power a screwdriver. To make the conversion, you only need to connect the power terminals of the charger output to the power supply of the electric motor.
If there is a charging device with continuously adjustable output voltage, you can use it as a power supply of 18 volts for a screwdriver.
Professional power supplies for screwdrivers
These devices are the most convenient to use, because they are made specifically to convert cordless models into mains-powered tools. They are available in different voltages: 12, 14, 18 and 24 volts.
Professional power supplies for screwdrivers
These devices don’t need any alterations. they’re already set up for your parameters. They are easy to connect. It consists in connecting the wires to the contact terminals of the electric screwdriver.
An important condition in all variants is the observance of polarity and the avoidance of work with a simultaneously connected device and a functioning battery.
It is possible to connect screwdrivers to the 220 V network using different power units
As step-down transformers and converters for converting cordless tools to mains, a variety of devices can act, sometimes the most unexpected. For example, a positive reputation in this matter have proven to be drivers for LED lights (12 V). Also quite successfully for this purpose are used backup batteries of alarm systems.
It is possible to connect an electric screwdriver from a car cigarette lighter. Of course, it will not achieve a lot of power, but it can screw self-tapping screws in the garage or at the cottage.
It is worth noting that not all breakdowns of power tools force to put an end to its operation. In the case of a cordless screwdriver, which has a failed battery, you can easily find a way to restore its performance.