Drill buyers often complain that the “native” screwdriver charger charges the battery too slowly. As a result, you have to repeatedly postpone work for 2-4 hours. There are 2 options for avoiding this situation. In the first case, you will need to purchase a new charger, in the second - do it yourself.

Varieties of batteries

To figure out how to make a charger for a screwdriver, you first need to study the types of batteries and their charging modes. There are 3 types of batteries:

Nickel-cadmium

This type is referred to as Ni-Cd, it is considered a good voltage source that is capable of delivering high power. The only drawback is that such batteries were included in the list of prohibited products for environmental nuances, so this variety will now be much less common on sale.

Nickel-cadmium batteries have an energy capacity of 1200 to 1500 mAh. The total power is provided and maintained by the number of cans inside

The maximum cell voltage is 1.2 V. The battery is charged with an electric current of 0.1-1 nominal capacity. It turns out that a battery with a capacity of 5 A * h is allowed to be recharged with a current of 0.5-5 A.

VIDEO: 5 rules for charging nickel-cadmium batteries

Another name is Pb with acid gel filling. They have average performance and low cost. Minus - the batteries have a large mass, due to which they make the device heavier. The main advantage is that it can be used in any position without electrolyte leaking out of the container.

Their main feature is high voltage and resistance, due to which, even by the end of the charge-discharge cycle, there is no sharp drop in voltage

The maximum voltage level of the cell is 2 V, while the battery charging current is always 0.1 C.

Lithium-ion batteries for screwdriver

The most common type due to the complete tightness of the container. This option is distinguished by increased power density, safety, environmental friendliness, low weight and ease of disposal.

Li-ion battery for screwdriver Li-ion 18650 Samsung 12.6V (Volt) 2400mAh

The lithium-ion cell has a maximum power of 3.3 volts. The voltage is allowed to increase smoothly at room temperature from 0.1 to 1 C. Thus, the charging process is accelerated. But this method is only suitable for those batteries that are not over-discharged.

It is important to remember here that the charge of the screwdriver occurs up to 4.2 Volts, exceeding it will affect a decrease in the operational life, a decrease will reduce the capacity. It is very important to keep track of the temperature when recharging.

When developing a charger circuit for a screwdriver with your own hands, it is very important to consider which battery you plan to charge. And also you need to additionally calculate its voltage - 12 Volts or 18 Volts. When using a charger for a screwdriver, it is necessary to monitor the process using a multimeter or a system with a voltage comparator, which has been pre-configured for a specific type of battery.

VIDEO: Rules for choosing a battery for a screwdriver

How to assemble the charger yourself

The creation of a homemade charger for a screwdriver requires compliance with safety precautions and work strictly according to a given scheme. You can use the drawing below, which is universal, since such charging equipment will be suitable for any type of battery. Here, only the charge current is an important parameter.

Homemade charging

When recharging, the current value fully corresponds to the current state of the battery, and at the end of the process, the indicator becomes slightly higher.

Diagram of the simplest charger for a screwdriver

Charger for a screwdriver acts as an electric current generator on the VT2 transistor. He, in turn, receives power through a rectifier bridge in contact with the lowering transformer. The charge current level is adjusted by the regulator of the resistor R1 when the battery is on. He will always remain the same. R3 operates as a rated current limiter. VD 6 - LED, it acts as an indicator that determines whether charging is in progress or has already completed.

All components from the charger circuit for the screwdriver are installed on printed circuit board, domestic devices KD202 and d242 can be used as diodes. It is required to place the elements in such a way that there is a minimum number of intersections on the board; it will be ideal if there are none. Leave at least 3 mm between parts.

The transistor is mounted on a 25-55 cm 2 heat sink. The field of connection of the charging components for screwdrivers must be covered with a case. There may be difficulties with terminals and battery connections. Therefore, it is better to modify the charger of the screwdriver by modernizing the old one:

• open the case of the obsolete charger;
• remove all component parts and other filling from it;
• install a homemade circuit in the case.

The following elements must be present in the diagram:

Item name	a brief description of
	Rectifier diode series 1N-4001
	Standard LED
	Multi-colored LED of various types
	Variable wire type resistor 10
	Resistor element of the MLT0.25 series for 330 Ohm
	Resistor MLT2,1 Ohm
	K5035 or 220 1000mF over 50 Volts
	Transistor part KT 361V
	Power transformer for 220/24 V and a power indicator of 100 W

Stages of work:

1. Select the most optimal dimensions for the circuit, which easily fit into the case with all of the above components.
2. Draw with a thread all its paths according to the basic drawing, etch in a copper frame and unsolder all the elements.
3. Place the heatsink on the aluminum plate so that it does not come into contact with any part of the board.
4. Fix the transistor securely with the M-3 nut.
5. Assemble the components strictly according to the diagram and solder the terminals to all the necessary parts observing the polarity. Lead out the electrical wire for the transformer.
6. Install the transformer itself together with a 0.5 A fuse in the case and equip it with an adapter to enable recharging.

VIDEO: How to charge a Li-ion battery from a screwdriver

Rating of chargers for a screwdriver

For those who do not plan to do self-assembly, we suggest choosing from an assortment of ready-made chargers from different manufacturers.

DEWALT DCB118

The FLEXVOLT DEWALT DCB118 universal tool is used to restore 54V DEWALT screwdriver batteries; any other device with a nominal voltage of 18 volts can be charged with equal success.

FLEXVOLT DEWALT DCB118

For convenience, an indicator is located on the case, so you can control the process. Type of rechargeable Li-ion batteries. Weight 850 gr. Equipment price 3500 rubles.

ONE + Ryobi RC18120

Stated as a dedicated charger only for charging Ryobi ONE + batteries. The advantage of having only one power supply - due to this, the weight of the device is even reduced (only 460 grams), while the intelligent monitoring system IntelliCell ™ is introduced, when each cell is charged to the maximum for 40-50 minutes, while increasing the battery life ...

ONE + Ryobi RC18120

The voltage is 18 volts, the battery type is nickel-cadmium and lithium-ion. There are 4 positions of the level indicator - 25… 50… 75… 100%. The case itself can be wall-mounted. There is a light indication of the level. The cost of the device is 4850 rubles.

DC10WC (10.8V) Makita

The device is used to recover lithium ion batteries with a rated voltage of 10.8 volts. There is a light indication, but there is no automatic stop. It is advisable to control the time in order to prevent overfilling of the container.

DC10WC (10.8V) Makita

Weight 1200 gr. with relatively small dimensions - only 20 cm long. There is a 1-year manufacturer's warranty. Price RUB 2200

VIDEO: How to properly charge Li-ion

Content:

All battery powered screwdrivers are equipped with chargers. However, some of them charge the battery very slowly, which creates certain inconveniences with intensive use of the tool. In this case, even the two batteries included in the kit do not allow the normal duty cycle to be set. The best way out of this situation would be a self-made screwdriver charger according to the most suitable scheme.

Screwdriver device

Despite the variety of models, the general device of the screwdrivers is quite universal, and the principle of operation is almost the same. They can only differ appearance, the arrangement of individual parts, the presence or absence of additional functions.

The power supply of screwdrivers can be 220V mains or rechargeable. The general design of a screwdriver includes the following elements and components:

• Frame. It is made of hard plastics, which contributes to a lighter construction and lower costs. Some models use metal alloys for increased strength. It is a pistol with a comfortable grip; when disassembled, it is divided into two halves.
• Cartridge. The attachments are fixed in it, to which the rotational movement is then transmitted. Typically a three-jaw, self-clamping and self-centering device is used. Inside there is a hexagonal recess where the nozzle shank is inserted. For fixing in the chuck, the nozzles are inserted between the cams and clamped by rotating the coupling.
• Electrical part. Consists of a small electric. Mains powered devices use two-phase AC motors rated for 220V. They are started using a starting capacitor. Cordless screwdrivers are equipped with DC motors. D.C comes from a battery made in the form of a set of elements combined in a common housing. The power of the screwdriver is determined by the output voltage of the battery.
• Chain elements. To turn it on, use a special button located on the handle. Typically, pushbutton switches are paired with voltage regulators. That is, the amount of voltage applied to the motor depends on the force applied when the button is pressed. The shift lever is also installed here, which provides a reverse rotation of the shaft due to the change in the polarity of the electrical signal. From the button, the signal goes directly to the rotor through the manifold. The electrical contact is provided by graphite brushes of certain sizes.
• Mechanical parts and details. The design is based on a planetary gearbox, with the help of which the torque is transmitted from the shaft to the output spindle. The carrier, ring gear and satellites are used as additional elements. All parts are located inside the body and in turn interact with each other.

An important component is the rotation control clutch, which sets a certain torque. With its help, the rotation of the shaft stops after screwing in the screw. Stopping occurs due to increased resistance to rotation. This measure prevents stripping of the threaded part of the screw and the failure of the screwdriver itself.

Charger circuits for screwdrivers

The same screwdrivers can use different types of batteries with different parameters and technical characteristics... In this regard, they require different chargers. Therefore, before you buy or make a charger for a screwdriver with your own hands, you need to determine the type of battery and operating conditions. In addition, it is recommended that you study the basic circuits most often used in chargers.

Microcontroller charging. Placed in a regular case, equipped with sound and light signaling of the beginning and end of the charge. This circuitry ensures correct battery charging. At the beginning of work, the LEDs light up and then go out. The indication is accompanied by a sound signal. In this way, the functionality of the device is tested. After that, the red LED starts blinking evenly, which indicates the normal charging process.

When the battery reaches a full charge, the red LED stops blinking, and instead of it, the green one lights up, accompanied by a sound signal. This means that charging is complete.

Setting the voltage level that should be on a full charge is carried out using variable resistor... In this case, the value input voltage equal to the voltage of a fully charged battery plus one volt. The circuit uses any one that has a P-channel and is most suitable for current characteristics.

In order to ensure charging at 14V, the input voltage must be at least 15-16V. The threshold that disconnects the charger is set with a variable resistor at 14.4V. The charging process itself takes place in the form of pulses displayed on the LED. In the intervals between the pulses, the voltage on the battery is monitored and upon reaching the desired value, a sound signal is given together with the blinking of the LED about the end of charging.

There are other charger circuits as well. For example, a charger for a drill / screwdriver works with a voltage of 18 volts. When charging the battery at 14.4V charging current selected with a resistor.

Charging for a screwdriver with your own hands

The problem of making a charger with your own hands does not arise so often, due to the large number of options suitable for almost all models of screwdrivers. It's just that sometimes situations arise when there is no charging, or it suddenly failed, and there is no way to get a new one. In this case, you can try to make your own charger.

You should first stock up on all the necessary materials. You will need an inoperative battery, a battery glass, a soldering iron, a thermal gun, a regular Phillips screwdriver, a drill and a sharp knife with replaceable blades. After that, you can start making the charger. First of all, the charging cup is opened, after which all conductors are soldered from the terminals. Next, the internal electronics are removed. When performing this operation, the polarity of the terminals must be observed so that in the future there will be no confusion and errors.

Open the case of a non-working battery and carefully unsolder the wires from the terminals. For further work, you will need a connector and a top cover. Plus and minus on the terminals are marked with a pencil or marker. At the base of the charging cup, holes are outlined through which the prepared cover and the leads of the supply wires will be attached. The conductors are carefully passed through the holes, observing the polarity, after which they are connected to the terminals and connectors by soldering.

Next, the body needs to be fastened with special hot melt glue, the bottom cover is fastened to the base of the glass using self-tapping screws. The resulting structure must be inserted into the battery and the charging process begins. A flashing light will indicate correct assembly of the device. Few chargers are equipped with so-called smart systems that significantly extend battery life. This problem can be solved by a charger for an 18 volt screwdriver.

A voltage stabilization system and a charging current limitation are added to the design of conventional charging. The result is a design of a nickel-cadmium battery with a capacity of 1200 mAh. Charging will take place at safe mode, the maximum current is not higher than 120 mA, but this will take more time than usual.

There is in every house where basic repairs are carried out. Any electrical appliance requires stationary electricity or a power supply. Since the most popular are cordless screwdrivers, a charger is also required.

It comes complete with a drill, and like any electrical appliance can fail. So that you do not face the problem of non-working equipment, we will study the general description of chargers for a screwdriver.

Types of chargers

Analog with built-in power supply

Their popularity is due to their low cost. If the drill (screwdriver) is not intended for professional use, the duration of the work is not the very first question. The task of a simple charger is to get constant pressure with sufficient current load to charge the battery.

Important! To start charging, the voltage at the output of the power supply must be higher than the nominal value of the battery.

This charging works according to the principle of a conventional stabilizer. For example, consider a charger circuit for a 9-11 volt battery. The type of batteries does not matter.

Hand tools with self-contained power supplies are developing rapidly and successfully. One of the most important areas is the improvement of storage batteries and their maintenance. The key to long-term and high-quality operation of battery power supplies is the charger. Now there are many companies on the market that produce their own independent power tools and blocks for charging them. One of the popular brands of hand tools is Interskol. Together with power supplies, the company produces "own" chargers for the interskol screwdriver battery.
We will consider the operation of the charger in this article. But, first you need to understand the principle of the power supply device.

The principle of operation of the block

The principle of operation of a storage battery is that when charging under the action of an applied voltage, charged electrons from the anode are introduced into the active part of the charge holding - the cathode. After complete saturation of the active element with electrons, charging is completed. When the load is connected, the movement of electrons occurs in the reverse order, while a potential difference is created on the electrodes, or a voltage, denoted by the Latin letter - U B (Volt). The number of charged electrons in the active layer of the cathode is defined as the capacity of the battery.

Capacity is one of the most important parameters, which directly gives the concept of capacity. The physical quantity is power, denoted by P (Watt), which is determined by multiplying voltage by current. So, if, on a 12V assembly, there is a designation of 2 Ampere-hour (A / h), this means that a 12-volt battery can give 2 amperes for an hour at a stable voltage.
The battery power is calculated using the formula P = I * U and will be equal to P = 2 * 12 = 24W (A * h). But if the voltage changes to 18V, then the power is P (W). will be equal to 36 watts.

Variety of battery assemblies

The power supply unit consists of single elementary parts of a standard size, assembled in series, in parallel or in a mixed circuit. Currently, nickel-cadmium (Ni-Ca), nickel-metal hydride (Ni-MH) and lithium-ion (Li-ion) elementary sources are used. These batteries are assembled into a single unit, they can be round, square, or flat. Depending on the active component, each battery is manufactured with a voltage of 1.2 to 3.6V. To increase the voltage, they are connected in series, to increase the capacity (power) in parallel, a mixed connection is also used. So, for example, in order to gain a voltage of 12V, it is necessary to connect 12 elements of 1V in series. And in order to double the power, the same elements must be connected in parallel.

First builds

The very first assemblies were assembled from elementary batteries with a cadmium-nickel active component. Assemblies with (Ni - Ca) possessed a number of exceptional properties: they were not afraid of working in the cold; the charging cycle reached 300 cycles. The battery can be kept in a usable condition for many years. But, along with their advantages, they have a significant drawback - this is the "memory effect", in other words, the assembly could not be left in a charged state, since active metal - cadmium, under the action of charged electrons, was oxidized, the battery decreased its initial capacity. And, although the manufacturer's passports contained recommendations for correct operation, many users did not follow them, as a result, the preparation of the battery for storage (the discharge after each work should remain no more than 30-40%) was not performed and the batteries did not withstand their warranty period.

Nickel - metal hydride batteries

The next step in the development of self-contained power supplies were batteries with a nickel-metal hydride (Ni-MH) active component. Manufacturers positioned the product as devoid of the main drawback (Ca-Ni) "memory effect". But, after practical application, it turned out that the main drawback decreased slightly, and the new active layer acquired additional negative properties: it could not work at negative temperatures, and the cost turned out to be much more expensive. Therefore, the production of these elements was quickly abandoned, especially since a new active component, lithium-ion, was developed and offered to the market.

Lithium Ion Batteries

Lithium-ion (Li - ion) products turned out to be not very expensive, but compared to the previous ones, they acquired several significant advantages:

• discharge cycle - charge increased from 300 to 400;
• reduced self-discharge;
• the memory effect is almost completely eliminated.
• the full charge time has been reduced to one hour.

But, undesirable properties, nevertheless, could not be avoided - this is uncontrolled heating to a high temperature during overvoltage. If a small overvoltage is possible in a device where batteries are used, an internal short circuit is possible in the cells and the active layer will be very hot. This was especially true for products with a small power of 12V. To reduce these shortcomings, Interskol has developed chargers capable of analyzing not only the charging process, but also each element separately.

Attention! separate chargers are required for each type of battery.

Charger design

The simplest circuit solution may be to connect the batteries of the 12 volt interskol screwdriver for Ni - Ca batteries. The station is assembled from the most necessary elements for lowering, rectifying and stabilizing the current. Let's take a closer look at the work of the elements. The secondary winding of the transformer is designed for a voltage of 15 - 17 V and a current of at least 5A. Undervoltage at the output of the secondary winding are straightened diode assembly or a diode bridge assembled from individual diodes with a power of at least 1A. To smooth out the ripple, it is worth electrolytic capacitor at 100 μF. For indication, an LED is used, which is installed in the collector circuit of the transistor and opens when voltage is applied to the base through resistance R2 after closing the charging circuit. The required voltage of 12V is provided by the VD1 Zener diode. This circuit provides a full charge of the battery in 4-5 hours.

Improved charger circuit of the Interskol CDQ-F06K1 screwdriver

with stabilization of the charging current, Interskol was developed on the HCF4060BE microcircuit. The microcircuit is a 14-bit master oscillator with the help of which the bipolar transistor S9012 is controlled. The load of the transistor is the S3-12A relay. The introduction of the counter into the circuit allows the circuit to work as a timer, which turns on the relay for a given time, thereby allowing the setting of the 12V charger modes.

Consider the operation of the circuit when the JDQK1 relay is connected to the network. The microcircuit receives power from the VD 6 12V zener diode - this zener diode sets the setting voltage to 12V, after which the power is supplied to the 16th pin of the microcircuit. After energizing the microcircuit, current pulses are fed to the base of the S9012 transistor, opening it.

The transistor opens and the voltage goes to the contacts of the JDQK1 relay, the contacts of which are closed and the charge current flows to the charging unit. The VD5 valve is installed to protect the battery from reverse discharge if the mains supply is disconnected. The transformer is used in a circuit with a power of 25 - 30 W, after the secondary winding in front of the rectifier diode bridge, a 5 A fuse is installed. Such a circuit allows you to connect the network without worrying about disconnecting and monitoring the load. Red LED indication indicates charging, green LED indication of charging termination.

Attention! Before placing Ca-Ni batteries at the station, it is necessary to makedetente battery at least 70% of its full capacity.

Station Interskol for Ca-Ni assemblies 12V DA-10 / 12ER

This device is a small box with a slot for installing a battery. power supply from the 220V network. Cord length 2.5 m. There is a charging indicator. The estimated price of the product is 1000 rubles. There is no terminating resistor to discharge the battery to the required voltage (5 V). Weight 1.2 kg. There is a red indication - charging. Green indicates that the battery is fully charged.

Features of charging blocks Interskol and troubleshooting

One of the distinctive features of Interskol charging units is the absence of a mains fuse and the use of a thermal fuse in the step-down transformer circuit. If it is difficult to find the malfunctions of the electronic elements in the circuit, then one of the malfunctions associated with the thermal fuse can be eliminated on its own. This is a step-down transformer. The fact is that instead of the mains fuse, a thermal fuse is installed at the input of the primary winding, which is set to a temperature of 130 ° C

Where to buy a charger for the Inteskol screwdriver

As for the purchase of hand tools or chargers of any design, they can be purchased at specialized or dealer centers of the company.

Their capacity is on average 12 mAh. In order for the device to always remain in working order, a charger is needed. However, they are quite different in voltage.

Nowadays, models are produced for 12, 14 and 18 V. It is also important to note that manufacturers use various components for chargers. In order to understand this issue, you should take a look at the standard charger circuit.

Charging circuit

Standard electrical circuit The screwdriver charger includes a three-channel type microcircuit. In this case, four transistors for the 12 V model are required. In terms of capacity, they can be quite different. In order for the device to cope with the high clock frequency, capacitors are attached to the microcircuit. They are used for charging both impulse and transient types. In this case, it is important to take into account the characteristics of specific batteries.

Directly thyristors are used in devices for current stabilization. In some models, open-type tetrodes are installed. They differ in current conductivity. If we consider modifications for 18 V, then there are often dipole filters. These elements allow you to easily cope with network congestion.

12V modifications

A 12 V screwdriver (diagram shown below) is a set of transistors with a capacity of up to 4.4 pF. In this case, the conductivity in the circuit is provided at a level of 9 microns. To prevent the clock frequency from increasing sharply, capacitors are used. The resistors in the models are mainly used field.

If we talk about charging on tetrodes, then there is additionally a phase resistor. It copes well with electromagnetic vibrations. Negative resistance with 12 V charges is maintained at 30 ohms. They are most often used for 10 mAh rechargeable batteries. Today they are actively used in models brand"Makita".

14 volt chargers

The charger circuit for a 14 V transistor screwdriver includes five pieces. Directly the microcircuit for converting current is only suitable for a four-channel type. Capacitors for 14 V models are pulsed. If we talk about batteries with a capacity of 12 mAh, then tetrodes are additionally installed there. In this case, there are two diodes on the microcircuit. If we talk about the charging parameters, then the current conductivity in the circuit, as a rule, fluctuates around 5 microns. On average, the capacitance of the resistor in the circuit does not exceed 6.3 pF.

Directly loads of charging current at 14 V are able to withstand 3.3 A. Triggers in such models are installed quite rarely. However, if we consider the Bosch brand screwdrivers, then they are often used there. In turn, in the Makita models, they are replaced by wave resistors. In order to stabilize the voltage, they fit well. However, the charging frequency can vary greatly.

18V model circuits

At 18 V, the charger circuit for a screwdriver assumes the use of transistors only of the transition type. There are three capacitors on the microcircuit. Directly the tetrode is installed with a grid trigger is used in the device to stabilize the limiting frequency. If we talk about the charging parameters for 18 V, then it should be mentioned that the current conductivity fluctuates around 5.4 microns.

If we consider chargers for Bosch screwdrivers, then this figure may be higher. In some cases, chromatic resistors are used to improve signal conductivity. In this case, the capacitance of the capacitors should not exceed 15 pF. If we consider chargers of the "Interskol" trademark, then they use transceivers with increased conductivity. In this case, the parameter of the maximum current load can reach 6 A. At the end, mention should be made of the Makita devices. Many of the battery models are equipped with high quality dipole transistors. They cope well with increased negative resistance. However, problems in some cases arise with magnetic vibrations.

Chargers "Intreskol"

The standard charger of the Interskol screwdriver (the diagram is shown below) includes a two-channel microcircuit. Capacitors are selected for it all with a capacity of 3 pF. In this case, the transistors for 14 V models are of the pulse type. If we consider modifications for 18 V, then there you can find variable analogs. The conductivity of these devices is capable of reaching 6 microns. In this case, the batteries are used with an average of 12 mAh.

Scheme for the Makita model

The charger circuit has a three-channel type microcircuit. There are three transistors in total in the circuit. If we talk about 18 V screwdrivers, then in this case the capacitors are installed with a capacity of 4.5 pF. Conductivity is provided in the region of 6 microns.

All this allows you to remove the load from the transistors. Directly, tetrodes are used of an open type. If we talk about modifications for 14 V, then the chargers are available with special triggers. These elements allow you to perfectly cope with the increased frequency of the device. At the same time, they are not afraid of horse racing.

Bosch screwdriver charging devices

The standard Bosch screwdriver includes a three-channel type microcircuit. In this case, the transistors are of the pulse type. However, if we talk about 12 V screwdrivers, then transitional analogs are installed there. On average, they have a bandwidth of 4 microns. Capacitors in devices are used with good conductivity. The chargers of the presented brand have two diodes.

Triggers in devices are used only for 12 V. If we talk about the protection system, then only open transceivers are used. On average, they are capable of carrying a current load of 6 A. In this case, the negative resistance in the circuit does not exceed 33 ohms. If we talk separately about modifications for 14 V, then they are produced for 15 mAh batteries. Triggers are not used. In this case, there are three capacitors in the circuit.

Scheme for the "Skill" model

The charger circuit includes a three-channel microcircuit. In this case, the models on the market are presented at 12 and 14 V. If we consider the first option, then the transistors in the circuit are of a pulse type. Their current reducibility is no more than 5 microns. In this case, triggers are used in all configurations. In turn, thyristors are used only for charging at 14 V.

Capacitors for 12 V models are installed with a varicap. In this case, they are not able to withstand large overloads. In this case, the transistors overheat quite quickly. There are three diodes directly in the 12V charging.

Application of the LM7805 regulator

The charger circuit for a screwdriver with an LM7805 regulator includes only two-channel microcircuits. Capacitors are used on it with a capacity of 3 to 10 pF. Regulators of this type can most often be found in models of the "Bosch" trademark. They are not suitable directly for 12 V chargers. In this case, the negative resistance parameter in the circuit reaches 30 ohms.

If we talk about transistors, then they are used in models of a pulse type. Triggers for regulators can be used. There are three diodes in the circuit. If we talk about modifications to 14 V, then tetrodes are suitable for them only of the wave type.

Use of BC847 transistors

The charger circuit for the BC847 screwdriver is quite simple. The specified elements are used most often by the Makita company. They are suitable for 12 mAh batteries. In this case, the microcircuits are of a three-channel type. Capacitors are used with double diodes.

Directly triggers are used of an open type, and their current conductivity is at the level of 5.5 microns. In total, three transistors are required to charge 12 V. One of them is installed at the capacitors. The rest in this case are located behind the reference diodes. If we talk about voltage, then 12 V overload charges with these transistors are capable of transferring to 5 A.

IRLML2230 transistor device

Charging circuits with transistors of this type are quite common. The company "Intreskol" uses them in modifications for 14 and 18 V. In this case, the microcircuits are used only of the three-channel type. Directly, the capacitance of these transistors is 2 pF.

They tolerate overloads of current from the network well. In this case, the conductivity indicator in charges does not exceed 4 A. If we talk about other components, then the capacitors are installed of a pulse type. In this case, three of them are required. If we talk about 14 V models, then they have thyristors for voltage stabilization.