How To Power A Screwdriver From A 220 V Network
How to turn a cordless screwdriver into a cordless one Do not rush to get rid of an old screwdriver with a completely deflated battery. After all, such a screwdriver may well be connected to a household power supply.
Connecting a screwdriver to an external power supply
Please note that a self-modified screwdriver can be effectively used only at home, when doing a small amount of work. If we are talking about a screwdriver for a large construction site or manufacturing enterprise, then in this case, a hand-restored tool will not help the master.
Working with electric shock is always dangerous. The instructions below are intended only for those readers who have at least basic knowledge in the field of electrical safety (the level of an electrical fitter is 2-3 categories).
The mains adapter for the cordless screwdriver can be created as follows:
- Disconnect the old battery and disassemble it. The battery pack is easy to disassemble. You just need to unscrew all the screws around the perimeter of the battery cover.
- We remove all the components of the battery. You only need to leave the adapter to which the network wires will be soldered.
- We compare the characteristics of the electric current an external step-down transformer and a screwdriver motor. The author of the used a 36 (V) step-down transformer, consisting of 2 coils of 18 (V) each. The transformer is marked TS-250-36. And the drive system of the power tool (screwdriver) is designed to operate on a 12 (V) network. The electrician had to get out of the situation in the simplest way, he disconnected the coils (36-18 = 18).
- One of the coils additionally contained part of the copper wire is unwound, which made it possible to reduce the voltage from 18 to 12 (V). The master reduced the winding until the output voltage was 11.2 (V). This is done in order to compensate for the voltage rise that will occur after the rectifying capacitor.
- To the middle terminals of the diode bridge we solder the wires of the secondary winding. A diode bridge is required to convert direct current to alternating pulsating current. The current strength of the diode bridge must correspond to the current strength of the screwdriver.
- We solder the rectified current output wires to the diode bridge. These contacts are located at the edges of the diode bridge.
- We solder a pre-prepared cable to the outgoing wires of the diode bridge, which will connect the transformer and the screwdriver itself. It is better to take a longer cable, at least 2 meters.
- We connect the capacitor in parallel. The operating voltage of the capacitor should be 2 times the voltage of the screwdriver. The capacitance of the capacitor must be at least 470 (μF). Below is a diagram of the above circuit.
- We connect the power wire directly to the terminals of the screwdriver. At this stage, you need to check the performance of the electrical circuit.
- Checking the operation of the tool, in parallel we control the voltage. Without load, the voltage can reach 15 (V). This is normal, because with direct rotation of the spindle, the voltage drops to 11.5 (V), which fits into the tolerance range.
- Now you need to make wired connections more practical and secure. To do this, solder the power cable to the contacts of the plug-in unit, where the battery pack for the screwdriver was previously located.
- We solder the wires with respect to polarity.
- We check the operation of the screwdriver in real conditions.
Below is attached a, on the basis of which the instruction was created.
How to turn a cordless screwdriver into a cordless one
Yes, there are many advantages to using cordless power tools. This is both practicality and autonomy, and the same aesthetics. But when using battery technology, the day certainly and certainly comes when The battery completely loses its original performance. That is, the battery power supply for the screwdriver ceases to hold a charge, which is why the battery is discharged literally in the first minutes of operation.
Everything would be fine, but manufacturers of cordless power tools, even from among the eminent ones, do not produce battery packs separately for your technique. It’s all about the economy. Thus, manufacturers stimulate demand for their products.
The average service life of a cordless screwdriver does not exceed 2-3 years. After this time, the battery of electrical engineering almost completely loses its capacity. The owner of an old screwdriver has several ways: to dispose of the old tool, or try to restore its working capacity.
It should be noted right away that you will not be able to put a “deflated” battery on your feet. But instead of battery you can try use the household power supply. To do this, you just need to connect the 12 or 18 Volt screwdriver power supply to the cordless tool, depending on the type of its drive.
The above-described principle of powering a screwdriver with a dead battery is far from the only one. The instructions show the simplest method. As you can see, the presence of a large external transformer spoils the whole aesthetics and practicality of the instrument, which, according to the initial idea, should be mobile and lightweight.
A special board based on the IR2157 microcircuit will help to make the power supply scheme more professional. The master will only need to apply a transformer winding, a capacitor and a diode bridge in the board, corresponding to the parameters of a particular screwdriver taken.
Due to the compact dimensions of the board, it can be neatly placed in the battery pack housing. Below is attached an auxiliary, the author of which assembles a board on an IR2157 microcircuit with his own hands, and also powers a cordless screwdriver with it.
If you cannot assemble this board with your own hands, then it does not matter. The IR2157 can be purchased from any radio market. It remains only to modify the transformer and the diode bridge with a capacitor.
Replacing a faulty charging board with a power supply unit from a computer
In the case when the charging board is faulty in the screwdriver control unit, in order to make the network option, a power supply unit is installed with parameters suitable for voltage and power. Sometimes the power supply comes from a personal computer. It should be borne in mind that the mains power is converted to 12 volts DC, the screwdriver at idle consumes up to 4A, for a short time at the moment of tightening. than 40A, then the peak value of power consumption can be up to 480 W.
You can install a PSU from a laptop, they are compact and easy to use, but the maximum power of these models is within 100W, a little more is not always enough.
Laptop power supply
The output voltage is 19V, there are screwdrivers with such a power supply.
Power (P) = 19 A x 6.15 A = 117 W, then you can add a 12V converter, and the screwdriver will idle and tighten the bolts with little effort. When screwing self-tapping screws into a dense wooden surface, such a power supply unit may not last long. It will burn out.
The location of the power supply inside the PC system unit
It is safer to use power supplies from system units of stationary computers. They are more powerful and in all respects are suitable for connection to screwdrivers.
The peak power of such a power supply is 500W; the nominal load for long-term operation is 460W, this is just what you need for a screwdriver with a 12V power supply.
Ax500-A board in a housing
There is a fan on the top cover of the metal case, which is connected via connectors to the board. Ventilated cooling allows the PSU to withstand high peak loads of 500W for several minutes. Sometimes the fans are located on the side walls, depending on the PSU model.
To connect such a power supply to a screwdriver, you need to perform just a few operations:
- Disconnect all power supply connectors from the motherboard and other elements of the system unit;
- Unscrew the fastening screws on the power supply unit and the system unit, then remove it from the system unit;
- There are no problems with connecting to a 220V network, a wire with a connector is included in the power supply kit;
- You will have to look for a 12 volt output, there are even two of them in this PSU model, you can find it by the marking on the printed circuit board. On some connectors, the output voltage is written opposite the contacts;
Designation of contacts on power supply connectors
For your information. When there are no inscriptions, you can navigate by the color of the conductors; in this series, 12V power supplies are output from the board to the connector with wires with yellow insulation. The negative connection is done with black wires.
- To check the correctness of the selected pair, you need to turn on the power supply and measure the voltage with a multimeter;
Note! In our case, a pulsed power supply unit is used, which will not start outside the system unit circuit. Without going into the details of the operation of individual semiconductor elements, we will simply accept as an axiom that a refinement is needed, which consists in a simple jumper.
- The green wire, designed to turn on the power supply unit according to the standard scheme, must be connected to the black conductor, this is done right on the board. An extra piece of green wire is cut off, the remaining end is stripped and soldered to the board track to the black conductor;
Modification in the power supply unit AX500-A, installation of a jumper
- After the completion of the power supply unit, you can plug it into the network and check the presence of 12V on the selected pair of wires with a multimeter;
- The yellow and black conductors can be lengthened and the connector soldered to them;
- In the battery case for connecting a screwdriver, as in the previous cases, galvanic cans that have served their time are removed, and a mating connector is installed to the mowing line from the power supply. The options may be different, you can solder the cord to the screwdriver, and the connector can be connected to the power supply, as you like;
The conclusions from the 12V power supply are soldered to the connector going to the screwdriver
- When soldering connectors and connections, do not forget to first put heat-shrinkable tubes on the wires and shrink them with a hot air gun, isolating the soldering points. As a last resort, do it with ordinary duct tape;
- Unused leads from the power supply unit can be bitten off or rolled up, the ends can be insulated and folded inside the case.
Block AX500-A with fan
Note! Remember to connect the fan when assembling the case. If you unsoldered or bit off during the installation process, you need to remember the connection contacts. The fan is powered by a 12V mowing line, by this indicator, you can easily find the screwdriver connection points.
Alteration with a standard battery and charging
Alteration of a cordless screwdriver to a network in this case assumes that the circuit is assembled on the basis of a standard charger. The following materials will be required:
- Accumulator battery;
- 2-3 meters of flexible stranded copper wire, with two conductors, section 2.5-4 mm2;
- The usual set of tools and consumables, a soldering iron, solder, electrical tape or heat shrink tubing of the appropriate diameter to the wires. To disassemble the screwdriver, you will need a screwdriver, side cutters and an assembly knife for cutting and stripping wires.
The sequence of operations in the process of converting a screwdriver into a network:
- The cover is removed from the charger case;
- The ends of the wire are soldered to the output contacts of the charger board, which are connected to the battery during charging, observing the polarity. A core with red insulation. To the “” terminal, with blue insulation. To the minus terminal;
- Polarities can be determined by the inscriptions on the board or the product case. For reliability, you can turn on the charging and measure the 12V output with a multimeter, and determine the contacts by polarity;
- Galvanic cells are removed from the battery case;
How to remove galvanic cells from the battery compartment
- The charging wire is connected to the contacts inside the battery case, observing the polarity.
Thus, the screwdriver is converted into a network one. When the device is plugged into the socket, the corresponding voltage of 12 or 18 VDC will be supplied to the input circuit of the screwdriver.
Polarity is recommended but not required. When the polarity changes, the motor shaft will rotate in the opposite direction, all modern screwdrivers have a polarity change switch, in fact, the rotation of the screwdriver chuck is reversed.
Important! The terminals on the charger board are usually made of a brass alloy, they must be soldered to the copper wires with acid solder or removed altogether, and the wires must be soldered onto the tracks of the printed circuit board.
Before soldering, holes are made in the battery and charger cases through which the wire is pulled. For a more rigid fixation within the body, you can tie it into a knot and wind electrical tape so that the winding diameter exceeds the hole Ø.
Alteration of a screwdriver for power from an outlet network
In the economy of a modern person, a screwdriver is not a rare tool, practically this tool is an analogue of an electric drill. The advantage of this type is considered to be autonomous power supply from a portable battery embedded in the lower part of the handle. The battery must be periodically charged from the mains through a special charger; with prolonged use, the battery fails, replacement is required, and they are not cheap. Therefore, many users are thinking about how to remake a cordless screwdriver so that it works on a 220 volt network.
General view of one of the options
Sometimes consumers decide that it is necessary to convert the screwdriver into a conventional electric drill powered from a wall outlet. The question arises of how to do this with less time and money. If you have certain knowledge in electrical engineering and practical skills, then powering a screwdriver from a 220V network is not difficult to do. There are several ways using various devices to convert electricity to the appropriate form to rotate the screwdriver motor.
Using a car battery charger
The principle is the same as using a computer power supply. It is necessary to purchase an old charger for the starter batteries. The modern fashion for compact impulse chargers has left analog linear devices with manual control of voltage and charge current behind. Therefore, such a device can be purchased on the automotive market for a symbolic cost.
Charger MAX INTER
It’s good if the voltage can be adjusted smoothly. In this case, your makeshift power supply will fit any screwdriver.
Converting it to a power tool is reduced to connecting the input of the electric motor to the power terminals of the charger.
Battery case power supply
Mobility remains, you are limited only by the length of the network cable. The only problem is how to squeeze a sufficiently powerful transformer into a small case.
We recall Ohm’s law again, and understand that a powerful 220 volt electric motor can be compact.
DIY screwdriver alteration
Consider the option with an external power supply.
Power supply of the screwdriver from the 220V network
Finally, I started to implement my old 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 charge. I had two copies at my disposal.
The first (black) has an operating voltage of 18 volts. It was him that I originally wanted to power from the network, tk. 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 something like a drill out of it. The second copy is designed for 12 volts. Served for quite a long time. The battery can of course be purchased with a new one or, in extreme cases, replaced by banks. But all the same, I want to have a ready-made tool at hand, especially since an electric drill is not always convenient to use. It is heavy. A power transformer will help us implement this idea.
A step-down transformer TS-250-36 was used. “250”. This is its nominal power, and the number 36 means that the output will have a voltage of 36 V. It has an O-shaped magnetic circuit. His 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 is wound in a similar way, which is located on top of the primary.
It is not difficult to distinguish the windings from each other in a step-down transformer, because the secondary is made of a thicker wire, and the one to which the mains voltage is supplied from a thinner wire. This is due to the fact that a smaller current flows through it.
The windings have a symmetrical arrangement and the two halves of 18 volts are connected with a wire (the connection point is clearly visible in the bottom photo). I will use one half.
But before you rewind the transformer, you need to take measurements. I urge you to be careful when working with current, not to touch live parts, and also always check if the measurement limit on the multimeter is set correctly.
On the right, the voltage is measured across half of the secondary winding. As you can see, the voltage is slightly higher than the rated values, because no load is connected here.
So I separated one half and now we proceed 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, it must be borne in mind 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 rise by about 1.4 times. Those. In the absence of load, the rectified voltage across the capacitor will be equal to the peak value.
As the secondary unwinds, we take measurements. Soon, I settled on 11.2 Volts. I was afraid of a drawdown when connecting the load.
With the transformer ready (although some may use the ready-made one with the desired parameters), now it’s time to get familiar with the circuit.
A diode bridge (VDS) must be soldered to the output of the transformer in order to convert the alternating current to constant pulsing.
The diode bridge can be assembled from separate diodes or use a ready-made one. When selecting it, you should take into account how many amperes your screwdriver consumes (pick up a bridge with a margin).
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 ripple. 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 a fuse can be added in the circuit in front of the transformer.
So, after connecting the circuit, I made measurements. The idle voltage at the output of the power supply (when no load is connected) is 15 volts. When you start the screwdriver, it sags to 11.5 volts, which is normal, so it’s okay. A fully charged new battery produced 13 volts.
This is how the tool looks 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.
In order to conveniently connect to the power supply, I disassembled the battery. We need contacts from him.
This detail needs to be tinned. I have brazed about Bosch using rosin, but in some cases I may need flux for aluminum brazing.
Of course, when soldering wires from the power supply, do not forget about the polarity, usually it is indicated on the battery case.
The compartment has become very light. The wire was sealed with hot melt glue.
Tests have shown that the screwdriver coped with the tasks when working from the power supply.
This article is available, which shows in detail the process of creating a power supply, rewinding a transformer, connecting and testing.