How to make a power supply for an electric screwdriver 18v with their own hands. instructions and diagrams

Any household tool that can function autonomously has a significant disadvantage. To maintain the battery in good condition is troublesome, in the process of work it requires regular charging, storage life is limited, and the cost of such a power source is such that the acquisition of a new one quite strongly “hits the “.

Yes, and find it will not always get, especially if the electric screwdriver is an old modification. The conclusion is simple. to make a power supply for an electric screwdriver for 18 volts with your own hands.

The most rational solution is to pick up components or remake an existing power supply from any technical device. It can be done with your own hands, without any help.

Other ways to upgrade

Radio amateurs offer many options for upgrading the tool. Some of them are very simple and are reduced to the use of ready-made power supplies, while others require knowledge in the field of electrical engineering and give the device versatility. Classification of methods:

  • Power adapter for the laptop.
  • Connecting a computer switching PSU (power supply).
  • Using a 12 V car battery.
  • Assembling a homemade power supply.

Using the charger for a laptop is the best solution to the problem. In addition, you need to know the parameters of an electric screwdriver and charger (there are 12 V and 19 V), and also take into account the size 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.

If you are using a switching power supply (350 W or more) for the PC (AT form factor) you need to find the voltage of 12 V on the connectors which supply a hard drive or CD-ROM drive. Take the wires out, and carefully cut and insulate the rest. You can build a case for PSU, which will allow to get current up to 16A. In addition, it is necessary to remove the starting protection. You need to connect the green wire to the black wire from this connector. These two methods are very simple and need no further description.

The car battery is the optimal source of electrical energy. Nothing has changed when upgrading the model other than connecting a different battery. A significant disadvantage is its weight. In addition, you need to build a battery charger or buy it 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 only applicable to 12 V screwdrivers, not 18 V. There are chargers designed for 19V. Getting 18 V is achieved by connecting the batteries in series, for example, 12 and 6 V. Note that the batteries must differ in terms of their characteristics only in terms of voltage. That’s why it is often necessary to assemble a power supply by yourself.

The variants of making a power supply

There are several options on how to convert the screwdriver to work from the mains. The task is to power the electric motor of the device with an intermediate source.

Using a laptop charger

To make a power supply of 12 V 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 those for powering a screwdriver. The main thing is that the output voltage corresponds to what you are looking for (12-14 volts).

To achieve this goal, you must first disassemble the battery and remove the defective elements. Then follow these manipulations:

  • We take the battery charger from a laptop.
  • Cutting off the output plug, stripping and tinning the wire ends.
  • We solder the stripped wires to the battery input wires.
  • Insulate the soldering points to avoid short circuits.
  • We make a hole in the case, so as not to squeeze the wire, and assemble the construction.

The base. the power block from a computer

To make this device you will need a block from a personal computer of format A. Т. It is easy to find, this is an old model of the power supply, which is easy to buy at any market of radio components. It is important to know that you can use a 300-350W unit with a current of 12 V at least 16 A.

AT format power supplies correspond to these parameters. On the case of this device there is a power button, which is very convenient for work. A cooling fan is installed inside and an overload protection circuit is mounted.

The order in which the unit is rebuilt:

  • Remove the lid of case B. П. Inside we see a board with many wires going to the connectors, as well as a fan.
  • The next step is to disable the power protection. Find the green wire on the square large connector.
  • Connect this wire to the black wire from the same connector. You can make a jumper from another piece of wire, or you can just cut it short and leave it in the case.

Then we find a smaller connector (MOLEX) in the output bundle and do the following things with it:

  • We leave the black and yellow wire and cut the other two short.
  • For convenient PSU positioning during work, solder an extension wire to the black and yellow wires.
  • Attach the other end of the extension cord to the contacts of the empty battery compartment. This must be done by soldering, you can make a good twist, while strictly observing the polarity.
  • Make a hole in the case, so that you don’t squeeze the wire during assembly. Your device is ready.

If you have the desire to ennoble your design, t. е. Hide it in another case, drill holes for air intake to prevent the PSU from overheating.

Power from a car charger

With a car battery charger, it’s 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 you have a device for charging with continuously adjustable output voltage, you can use it as a power supply 18 volt for a screwdriver.

Glamorous boudoir trees

The next year of the white metallic bull implies a decoration in white and pastel colors. Nothing red and flashy!

You need to remove the brightly colored tinsel. you only need the cone. And the rest is just a matter of seconds: wrap the cone with the lady’s ornament and fasten the ends.

Powering an electric screwdriver from 220V

I have finally started to implement my long-standing idea, namely, to provide power for an electric screwdriver from 220 volts. No doubt some of you also have a screwdriver, with a worn out, unusable battery that no longer takes a charge. In my location I had two copies.

The first (black) working voltage is 18 volts. It was the one I originally wanted to power from the mains, i.e.к. comfortable in the hand and quite powerful. But what’s missing is a button. Perhaps in the future I will cut the handle and make it like a drill. The second device is designed for 12 volts. Has served for quite a long time. Battery pack is of course possible to buy a new one, or as a last resort to replace the jars. But still want to have at hand always a ready tool, the more that an electric drill is not always convenient to use t.к. it’s heavy. A power transformer will help us to realize this idea.

A TC-250-36 step-down transformer was used. “250”. this is its rated power, and the number 36 means that the output voltage will be 36 V. It has an O-shaped magnetic core. The windings are arranged so that half of the primary is wound on the left side and the other half on the right. The secondary winding is wound in the same way, and is placed on top of the primary winding. It is easy to distinguish the windings from each other in a step-down transformer.к. the secondary is made of a thicker wire, and the one that receives the line voltage is made of a thinner wire. This is because it carries a smaller current.

The windings have a symmetrical arrangement and the two 18 volt halves are connected with a wire (the connection point is clearly visible in the bottom photo). I’m going to use one half.

But before you rewind the transformer you have to measure. I urge you to be careful when working with current, don’t touch live parts, and always check if the meter has the right measurement limit.

On the right is measuring the voltage at half of the secondary. As you can see, the voltage is slightly higher than the nameplate values, t.к. No load is connected here.

So I removed one half and now let’s disassemble the transformer. There was a large amount of paraffin between the layers of paper.

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

In determining the required voltage, you must take into account that after the transformer will be diode bridge, which will reduce the voltage by about a couple of volts. But adding a smoothing capacitor will cause a voltage increase of about 1.4 times. Т.е. With no load, the rectified voltage at the capacitor will be equal to the amplitude value.

As we unwind the secondary, we measure. Soon, I stopped at 11.2 volts, t.к. was afraid of sagging when connecting the load.

When the transformer is prepared (although some may use a ready made one with the right parameters), now it’s time to get acquainted with the schematic.

To the output of the transformer you need to solder the diode bridge (VDS), to convert the AC current into a DC pulsating. The diode bridge can be assembled from a separate diode or you can use a ready-made. When selecting it you should take into account how many amperes your electric screwdriver consumes (choose the bridge with a reserve).

Wires from the secondary winding solder to the diode bridge terminals, where the letters AC (alternating current).

power, supply, electric, screwdriver, your, hands

And after the bridge you need to solder a capacitor to smooth the ripple. Its voltage should exceed the voltage of the electric screwdriver at least twice. And the capacity is from 470 uF to 2200 uF.

If desired, you can add a switch and a fuse in the circuit before the transformer.

So after connecting the circuit I measured. Idle voltage at the output of the power supply (when the load is not connected) is 15 volts. When you start the electric screwdriver, it sags to 11.5 volts, which is the norm, so it’s not a big deal. Fully charged, the new battery produced 13 volts.

This is what the tool looks like on the inside. Here you find the limit of the button and you can see that the motor is controlled by a high-powered field-effect transistor.

To make it easy to connect the power supply I disassembled the battery. From it we need the contacts. This part needs to be tinned. I did the soldering with rosin, but in some cases you might need flux for aluminum soldering.

Of course when you solder the wires from the power supply do not forget about polarity, usually it is marked on the battery. The compartment is now very light. The wire was sealed with thermal adhesive.

Cordless to corded drill conversion without torque loss

The tests showed that the electric screwdriver performed as well as it could on the power supply.

There is a video attached to this article which shows in detail how to build a power supply, rewind the transformer, connect it and test it.

Replacing the nickel-cadmium batteries in an electric screwdriver with lithium batteries

Replace the batteries of an electric screwdriver with lithium batteries with your own hands by calculating their number, assuming that one cell requires 3.7 V. For example, for a 14.4V product, you must prepare four Li-Ion battery packs of 18650 standard.

It is also worth considering the difference in size. To change the battery you will need to buy a charge-discharge controller, which is installed additionally in the case with the banks. In addition, it is not ruled out that you will have to replace the charger.

What tools and materials are needed for manufacturing

People who know about electronics recommend putting the power supply inside the electric screwdriver in place of the battery. This will protect it from moisture, dust and dirt, and the tool itself will last longer.

Please note! To open the battery case, you can use an ordinary knife, passing it along the seam.

In addition, you may need these tools:

Important! The list of materials depends entirely on what kind of power supply you want to make and what circuitry is originally used. You can work with the car blocks, and you can take a banal power supply from a computer, but this option will be more cumbersome.

Preparation of tools for connection of homemade uninterruptible power supply

List of radio elements

Nameplate Type Nominal Quantity NoteMy Notebook ShopVD1-VD4








Diode KD2998V 4 Search in the store Otron Notepad
Capacitor 1.0 μF 1 400 В Store search Ottron Notepad
Capacitor 0.47 uF 1 160 В Search in the Otron store Notepad
Electrolytic capacitor 2200 uF 15 16 В Store Locator Ottron Into notebook
Electrolytic capacitor 1000 uF 4 16 В Search in the Otron store Notepad
Capacitor 1.0 uF 1 160 В Search in the Otron store Notepad
Fuse 3.16 А 1 see. Text Search in the Otron store Notepad
Transformer 220/8 В 1 see. text Search in the Otron store To the notebook
Add All

r9o-11 Published: 04.12.2015 0 1

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