Conversion of a screwdriver to mains power
The device of the screwdriver mechanism and the principle of the device. Battery design and battery types. Alteration of a screwdriver for power supply from a 220V network. Using an external power supply.
Car battery charger
The requirements for this device are the same as when using the computer unit.
If so, it is advisable to use a device with a built-in voltmeter and voltage regulation. In some models, a current-limiting resistance is installed inside. It must be short-circuited.
How to make a homemade power supply
In addition to the purchased one, you can make the power supply yourself. This requires a 160W transformer, such as were installed in tube TVs.
First of all, you need to determine the required number of turns. The procedure is as follows:
- Disassemble the transformer;
- Unwind all secondary windings from the coil;
- Wind 10 turns of wire;
- Assemble the transformer;
- Connect to a 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 lowering winding is wound with a wire with a cross section of 1mm² to reduce the voltage drop in the transformer.
There is an alternating voltage at the output of the transformer, and the device needs a constant one, therefore, 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 cells are removed.
Alteration of a screwdriver for power supply from a 220V network
If the battery fails and it is impossible to repair it, the only way out is to convert the cordless screwdriver into a network one.
In this case, the power of the power supply unit must exceed the power of the motor, taking into account possible overloads at the time of the completion of tightening. It is not indicated in the passport of the device, but this parameter is written on the body of the electric motor, or it can be calculated by connecting the device to a constant voltage source through an ammeter. For a 70W motor, a 120W power supply is sufficient.
Important! The charger is not powerful enough to operate. When converting a cordless screwdriver to a 220-volt mains screwdriver, you must use a different power supply.
DIY screwdriver alteration
Consider the option with an external power supply.
Battery Disadvantages
- Needs regular recharging. Sooner or later, batteries will use up their cycle life.
- The cheaper the tool, the faster the rework time will come.
There is nothing wrong with that, but you should be aware that the manufacturer saves as much as you do. Consequently, the most expensive unit (namely the battery) will be the cheapest when bundled.
As a result, we get an excellent tool with a serviceable motor and not a worn gearbox, which does not work due to a poor-quality battery.
There is an option to purchase a new set of batteries, or replace faulty batteries in the unit. However, this is a budget event. The cost is comparable to buying a new screwdriver.
The second option is to use a spare or old battery from the car (if you have one). But the starter battery is heavy, and using such a tandem is not very comfortable.
Using a power supply from a personal computer
On the radio market, you can purchase an old power supply from a personal computer for a small cost. We need a variant of the AT format, which had to be turned off by pressing the key after exiting the operating system.
Experienced users remember such system blocks. The advantage of such a power supply is also that it indicates an honest power. If it says 300W, it means you can safely remove 15-16 amperes from the 12-volt output (again referring to Ohm’s law). This is enough to power an average screwdriver.
Such blocks have a power button in the kit. Another advantage is the presence of a cooling fan and an advanced overload protection system.
If you are hiding the power supply in a beautiful case, do not forget to leave a hole for ventilation.
The connection is very simple. Black wire (-), yellow wire (12V).
Limitations – a screwdriver with a supply voltage higher than 14 volts will not work.
Schematic solutions of how to get a voltage of 12v from 220v without a transformer
Very often, users of electrical lighting devices and SBT are interested in: "How to get 12V or other low voltage without a 220-volt transformer?" Usually this question is asked by the owners of electronic equipment and equipment operating from power sources on a step-down mains transformer. This is all the more relevant, since the weight and dimensions of the power supply unit (PSU) often exceed those of a powered gadget or stationary device.
Charger
The most budgetary option, of course, is the use of a charger (charger) from a cell phone. The charger board has very small dimensions and is suitable for powering a 12 V gadget with a power of ≤ P nom. Power supply. It is only necessary to replace the half-wave rectifier in it with a rectifier with double voltage (one diode and one capacitor are added). After the upgrade, we get the required 12 volts with a current of 0.5A and full isolation from the network.
As an alternative, which does not require intervention in the design, a DC-DC step-up voltage converter (for example, a 2-amp, 30mm x 17mm x 14mm, costing 1) with a USB connector is connected to the charger output through an adapter. It is only required to set the required voltage of 12 V with a trimming resistor and connect the converter to a gadget or stationary electrical device.
With a resistor
The method is suitable for powering a low-current load, for example, an LED or a low-power LED lamp. The main disadvantage of a resistive circuit is low efficiency due to the dissipation of a large amount of active power spent on heating the resistor. In the simplest version, the power supply unit is a resistor voltage divider installed after the diode rectifier, from the lower arm of which the voltage is removed.