Homemade charger for lithium-ion batteries of a screwdriver. Charger for a screwdriver Charger for a screwdriver interskol 12 volt circuit

Without a doubt, power tools greatly facilitate our work and also reduce the time of routine operations. All kinds of self-powered screwdrivers are now in use.

Let's look at the device, circuit diagram and repair of a battery charger from an Interskol screwdriver.

First, let's take a look at the circuit diagram. It is copied from a real charger circuit board.

Charger circuit board (CDQ-F06K1).

The power part of the charger consists of a GS-1415 power transformer. Its power is about 25-26 watts. I calculated using the simplified formula that I already mentioned.

A reduced alternating voltage of 18V from the secondary winding of the transformer is supplied to the diode bridge through fuse FU1. The diode bridge consists of 4 diodes VD1-VD4 type 1N5408. Each of the 1N5408 diodes can withstand a forward current of 3 amperes. Electrolytic capacitor C1 smoothes out voltage ripples after the diode bridge.

The basis of the control circuit is a microcircuit HCF4060BE, which is a 14-bit counter with elements for the master oscillator. It controls the pnp bipolar transistor S9012. The transistor is loaded onto the electromagnetic relay S3-12A. The U1 chip implements a kind of timer that turns on the relay for a given charging time - about 60 minutes.

When the charger is plugged in and the battery is connected, the JDQK1 relay contacts are open.

The HCF4060BE chip is powered by a zener diode VD6 - 1N4742A(12V). The zener diode limits the voltage from the mains rectifier to 12 volts, since its output is about 24 volts.

If you look at the diagram, it is not difficult to notice that before pressing the “Start” button, the U1 HCF4060BE chip is de-energized - disconnected from the power source. When the "Start" button is pressed, the supply voltage from the rectifier is supplied to the 1N4742A zener diode through resistor R6.

The supply voltage through the open transistor S9012 is supplied to the winding of the electromagnetic relay JDQK1. The relay contacts close and power supply is supplied to the battery. The battery begins to charge. Diode VD8 ( 1N4007) bypasses the relay and protects transistor S9012 from a reverse voltage surge that is formed when the relay winding is de-energized.

The VD5 diode (1N5408) protects the battery from discharge if the mains power is suddenly turned off.

What happens after the contacts of the "Start" button open? The diagram shows that when the contacts of the electromagnetic relay are closed, the positive voltage through the diode VD7 ( 1N4007) is supplied to the zener diode VD6 through the quenching resistor R6. As a result, the U1 chip remains connected to the power source even after the button contacts are open.

Replaceable battery.

The GB1 replacement battery is a unit in which 12 nickel-cadmium (Ni-Cd) cells, each 1.2 volts, are connected in series.

In the schematic diagram, the elements of a replaceable battery are outlined with a dotted line.

The total voltage of such a composite battery is 14.4 volts.

There is also a temperature sensor built into the battery pack. In the diagram it is designated as SA1. Its operating principle is similar to the KSD series thermal switches. Thermal switch marking JJD-45 2A. Structurally, it is fixed to one of the Ni-Cd elements and fits tightly to it.

One of the terminals of the temperature sensor is connected to the negative terminal of the battery. The second pin is connected to a separate, third connector.

The operating algorithm of the circuit is quite simple.

When plugged into a 220V network, the charger does not show its operation in any way. The indicators (green and red LEDs) do not light up. When a replacement battery is connected, the green LED lights up, indicating that the charger is ready for use.

When you press the "Start" button, the electromagnetic relay closes its contacts, and the battery is connected to the output of the mains rectifier, and the battery charging process begins. The red LED lights up and the green LED goes out. After 50 - 60 minutes, the relay opens the battery charging circuit. The green LED lights up and the red LED goes out. Charging is complete.

After charging, the voltage at the battery terminals can reach 16.8 volts.

This operating algorithm is primitive and over time leads to the so-called “memory effect” of the battery. That is, the battery capacity decreases.

If you follow the correct battery charging algorithm, first each of its elements must be discharged to 1 volt. Those. A block of 12 batteries needs to be discharged to 12 volts. The charger for a screwdriver has this mode: not implemented.

Here is the charging characteristic of one Ni-Cd battery cell at 1.2V.

The graph shows how the cell temperature changes during charging ( temperature), voltage at its terminals ( voltage) and relative pressure ( relative pressure).

Specialized charge controllers for Ni-Cd and Ni-MH batteries, as a rule, operate according to the so-called delta -ΔV method. The figure shows that at the end of charging the element, the voltage decreases by a small amount - about 10mV (for Ni-Cd) and 4mV (for Ni-MH). Based on this change in voltage, the controller determines whether the element is charged.

Also, during charging, the temperature of the element is monitored using a temperature sensor. The graph also shows that the temperature of the charged element is about 45 0 WITH.

Let's return to the circuit diagram of the charger from the screwdriver. It is now clear that the JDD-45 thermal switch monitors the temperature of the battery pack and breaks the charging circuit when the temperature reaches somewhere 45 0 C. Sometimes this happens before the timer on the HCF4060BE chip works. This happens when the battery capacity has decreased due to the “memory effect”. At the same time, such a battery is fully charged a little faster than in 60 minutes.

As we can see from the circuit design, the charging algorithm is not the most optimal and over time leads to a loss of battery capacity. Therefore, to charge the battery, you can use a universal charger, for example, such as the Turnigy Accucell 6.

Possible problems with the charger.

Over time, due to wear and moisture, the SK1 "Start" button begins to work poorly, and sometimes even fails. It is clear that if the SK1 button malfunctions, we will not be able to supply power to the U1 chip and start the timer.

Failure of the zener diode VD6 (1N4742A) and microcircuit U1 (HCF4060BE) may also occur. In this case, when you press the button, charging does not turn on and there is no indication.

In my practice, there was a case when the zener diode struck, with a multimeter it “ringed” like a piece of wire. After replacing it, charging began to work properly. Any zener diode with a stabilization voltage of 12V and a power of 1 Watt is suitable for replacement. You can check the zener diode for breakdown in the same way as a regular diode. I have already talked about checking diodes.

After repair, you need to check the operation of the device. By pressing the button we start charging the battery. After about an hour, the charger should turn off (the “Network” indicator (green) will light up). We remove the battery and make a “control” measurement of the voltage at its terminals. The battery should be charged.

If the elements of the printed circuit board are in good working order and do not raise suspicions, and the charging mode does not turn on, then you should check the thermal switch SA1 (JDD-45 2A) in the battery pack.

The circuit is quite primitive and does not cause problems when diagnosing faults and repairing even

Charger Circuit for Interskol 12V Screwdriver

Without hesitation, power tools significantly simplify our work and also reduce the time of routine operations. Various self-powered screwdrivers are currently in use.

Let's look at the device, the circuit diagram and the repair of a charger for batteries from a screwdriver from the Interskol office.

First of all, let's take a look at the circuit diagram. It is copied from a real charger circuit board.

Charger IC (CDQ-F06K1).

The power part of the charger consists of a GS-1415 power transformer. Its power is about 25-26 watts. I calculated using a simplified formula, which has already been discussed here.

A reduced alternating voltage of 18V from the secondary winding of the transformer is supplied to the diode bridge through fuse FU1. The diode bridge consists of 4 diodes VD1-VD4 type 1N5408. Any of the 1N5408 diodes can withstand a forward current of 3 amperes. Electrolytic capacitor C1 smoothes out voltage ripples after the diode bridge.

Control circuit base - microcircuit HCF4060BE, which is a 14-bit counter with elements for the master oscillator. It controls the pnp bipolar transistor S9012. The transistor is loaded onto the electrical relay S3-12A. The U1 chip implements a typical timer that turns on a relay for a given charging time - about 60 minutes.

When the charger is plugged in and the battery is connected, the JDQK1 relay contacts are open.

The HCF4060BE chip is powered by a zener diode VD6 - 1N4742A(12V). The zener diode limits the voltage from the mains rectifier to 12 volts, because its output is about 24 volts.

If you look at the diagram, it is easy to see that before pressing the “Start” button, the U1 HCF4060BE chip is de-energized - disconnected from the power source. When the "Start" button is pressed, the supply voltage from the rectifier is supplied to the 1N4742A zener diode through resistor R6.

Screwdriver charging. Repair of the Interskol 18 V screwdriver charger. Do it yourself.

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The supply voltage through the open transistor S9012 is supplied to the winding of the electric relay JDQK1. The relay contacts close and supply voltage is supplied to the battery. The battery begins to charge. Diode VD8 ( 1N4007) bypasses the relay and protects the transistor S9012 from a surge in the reverse voltage that appears when the relay winding is de-energized.

The VD5 diode (1N5408) protects the battery from discharge if the mains power is turned off.

What happens when you get tired of it, when the contacts of the "Start" button open? The diagram shows that when the contacts of the electric relay are closed, there is a positive voltage through the VD7 diode ( 1N4007) is supplied to the zener diode VD6 through the quenching resistor R6. During this process, the U1 chip remains connected to the power source even if the button contacts are open.

The GB1 replacement battery is essentially a unit in which 12 nickel-cadmium (Ni-Cd) parts are connected in turn, each with 1.4 volts.

In the schematic diagram, the elements of a replaceable battery are outlined with a dotted line.

The total voltage of such a composite battery is 14.4 volts.

There is also a temperature sensor built into the battery pack. In the diagram it is designated as SA1. Following the principle of operation, it is similar to thermal switches of the KSD series. Thermal switch marking JJD-45 2A. Structurally, it is fixed to one of the Ni-Cd parts and fits tightly to it.

One of the terminals of the temperature sensor is connected to the negative terminal of the battery. The 2nd pin is connected to a separate, third connector.

THE EASIEST UPGRADE to standard interskol charging for Li-ion-18650.

When connected to a 220V network, the charger does not perform its functions in any way. The indicators (green and reddish LEDs) do not shine. When a replacement battery is connected, a green LED lights up, which indicates that the charger is ready for use.

When you press the "Start" button, the electrical relay closes its contacts, and the battery is connected to the output of the mains rectifier, and the battery charging process begins. The red LED lights up and the green LED goes out. After 50 - 60 minutes, the relay opens the battery charging circuit. The green LED lights up and the reddish one goes out. Charging is complete.

After charging, the voltage at the battery terminals reaches 16.8 volts.

This method of operation is primitive and over time leads to the so-called “memory effect” of the battery. In other words, the battery capacity decreases.

If you follow the correct method of charging the battery, at the beginning any of its parts must be discharged to 1 volt. Those. a block of 12 batteries must be discharged to 12 volts. In the charger for a screwdriver, this is the mode not implemented.

Here is a textbook charging line for a 1.2V Ni-Cd battery cell.

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The graph shows how the cell temperature changes during charging time ( temperature), voltage at its terminals ( voltage) and relative pressure ( relative pressure).

Special charge controllers for Ni-Cd and Ni-MH batteries usually work according to the so-called delta.ΔV method. The figure shows that in the lower part of the charging of the element, the voltage decreases by a small amount - about 10mV (for Ni-Cd) and 4mV (for Ni-MH). Based on this change in voltage, the controller determines whether the element is charged.

Also, during charging, the temperature of the element is monitored using a temperature sensor. Here on the graph you can see that the temperature of the charged element is about 45 0 WITH.

Let's return to the circuit diagram of the charger from the screwdriver. It is now clear that the JDD-45 thermal switch monitors the temperature of the battery pack and breaks the charging circuit when the temperature reaches somewhere 45 0 C. This happens before the timer on the HCF4060BE chip is triggered. This happens when the battery capacity has decreased due to the “memory effect”. In this case, such a battery is fully charged a little faster than in 60 minutes.

As we examined from the circuit design, the charging method is not the most suitable and over time leads to a loss of electrical capacity of the battery. To charge the battery, use a universal charger, such as the Turnigy Accucell 6.

Over the years, due to wear and humidity, the SK1 “Start” button begins to work poorly, and even fails altogether. It is clear that if the SK1 button malfunctions, we will not be able to supply power to the U1 chip and start the timer.

Also contains a breakdown of the zener diode VD6 (1N4742A) and the U1 microcircuit (HCF4060BE). Then, when you press the button, charging does not turn on, there is no indication.

In my practice, there was a case when the zener diode struck, with a multimeter it “ringed” like a piece of wire. After changing it, charging began to work properly. Any zener diode with a stabilization voltage of 12V and a power of 1 Watt is suitable for replacement. You can check the zener diode for breakdown, just like an ordinary diode. I already talked about checking diodes.

After repair, it is necessary to check the operation of the device. By pressing the button we start charging the battery. After about an hour, the charger should turn off (the “Network” indicator (green) will light up). We remove the battery and make a “control” test of the voltage at its terminals. The battery must be charged.

In this case, the elements of the printed circuit board are in good working order and do not raise suspicions, and the charging mode does not turn on, then you should check the thermal switch SA1 (JDD-45 2A) in the battery pack.

The circuit is quite primitive and does not even cause problems when diagnosing a malfunction and repairing it, even for novice radio amateurs.

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Charger for a screwdriver - how to choose or whether you can make it yourself Screwdrivers are found in every family where simple repairs are made. Any electrical appliance requires stationary electricity or a power supply. Since cordless screwdrivers are very fashionable, a charger is also required. It comes complete with a drill...

A screwdriver is one of the most versatile power tools. Many people have seen this from their own experience.

However, even such a wonderful tool has its drawbacks. One of them is the charger. If it breaks, it can be difficult to find one suitable for the model you need. And even if there is one, the price is high, and it’s easier to buy a new screwdriver. Another problem can be slow battery charging.

Many users decide to make their own charger. In this article you will learn what is needed for this and how to make such a device for 12 and 18 volts.

Homemade charger for a screwdriver

Before you get started, you need to determine what type of battery is used in your screwdriver. They come in lead, nickel, lithium, and others. Depending on the type of battery, different charger designs are needed. After all, each battery has its own characteristics and operating rules.

Lithium-ion batteries are the most commonly used batteries today. Batteries of this kind are considered the safest and most environmentally friendly. When using them, the voltage must be taken into account accurately. Increasing or decreasing the voltage sharply reduces the operating time and capacity of such batteries.

Carefully! Heating a lithium-ion battery above 60 degrees can cause a fire or even an explosion.

Before you begin, make sure you have all the necessary knowledge in the field of electrical circuits and soldering.

To work you will need:

• charging glass;
• a battery that doesn't work;
• knife and blades;
• drill;
• soldering iron;
• wires no less than 15 cm long;
• screwdriver;
• heat gun.

The most common screwdrivers are those that use batteries with a voltage of 12 and 18 volts.

To remake the charger, you need to understand the design. The unit consists of a current generator on a composite transistor, which receives current from a rectifier bridge. It, in turn, is connected to a step-down transformer with the required output voltage.

It is necessary that the transformer produces the required power. This is important for long-term operation of the device. Otherwise it will burn. The current is regulated by a resistor when the battery is inserted. The current is constant throughout charging. And the higher the power of the transformer, the more stable the charge.

DIY charger for a 12 volt screwdriver

This unit is suitable for lithium-ion batteries from 900 mAh and more. To do it, you need to follow these steps:

1. First you need to take the charging glass and carefully open it.
2. After this, peel off the terminals and all electronics using a soldering iron.
3. Then you need to unsolder the plus and minus terminals of the idle battery, again using a soldering iron. To avoid mixing up the polarity, mark the pluses and minuses with a marker or pen.
4. In the disassembled charging cup, you need to mark where the wires will be located.
5. Then you need to drill the holes. The diameter can be increased using a knife.
6. After this, the wires are inserted into the holes drilled for them and soldered to the prepared glass, while observing the polarity.
7. Using a heat gun, attach the battery cap to the charging cup.
8. And at the end of all the operations performed, the bottom cover is attached back to the charging cup.

So you made the charger yourself.

Do-it-yourself charging for an 18-volt screwdriver

You can make an 18-volt charger according to the scheme described above. If the original block is in good condition, you can use it for remodeling. If not, you can use the power supply from your laptop as a basis. It produces just the right 18 volts.

You can make a unit according to a scheme often found on the Internet. This modification allows you to speed up battery charging time. According to the circuit, current flows into the battery, and control is carried out using a transistor. It affects the indicator readings. Then the current decreases as it charges, and the LED goes out.

As you can see, the device is far from the most complex. Any master can improve the charging unit for his screwdriver. This way you will make the charger more reliable, with the ability to quickly recharge batteries.

A cordless screwdriver is an alternative to a regular screwdriver for both small tasks and large home renovation projects. The tool is affordable, easy to use, and has the special advantage of eliminating the cords common to power tools. To periodically recharge the batteries, use a charger for a screwdriver.

Benefits of cordless tools

Today there are many devices that successfully cope with installation work using fasteners: screwdrivers, drills, drilling machines, many of them have a charger for a screwdriver.

Small, lightweight, mobile and self-contained screwdrivers have the following advantages:

Wireless power supply device

Sometimes for older tool models it is impossible to purchase a new charger and it is necessary to modify it or make a new one yourself. Lead-acid Ni-Cd and Li-ion batteries will require a charger circuit for an 18-volt screwdriver. The main features of this universal source are:

1. DC voltage.
2. Automatic shutdown when fully charged.
3. The maximum current is 5 amperes, batteries can be charged normally.
4. Fully customizable mode according to battery specifications.
5. Low cost.
6. Optimal electrical circuit. No special parts are required, they are all standard and easily available.
7. LED indicators to monitor cut-off and charging status.
8. Suitable for garages and home use.

This multi-purpose fixture is a 5 amp DC source, however, charging at a lower current may require an additional DC circuit between the input power supply.

When deep charging, the battery may overheat, which must be protected by automatic temperature controller circuitry or cooling fan. List of parts for repairing a screwdriver with your own hands:

1. Resistors.
2. Capacitors.
3. Simistry.
4. Zener diodes.
5. Gearbox.

Repair of current sources

Rechargeable batteries actually do not have complex spare parts, since they are assembled from simple charging elements. In order to determine the repair, you need to open the source and check for damage. Tools and materials that will be needed when performing repairs:

• Multimeter.
• Screwdriver.
• Electrical contact cleaner.
• Insulating tape.

There are times when the coil of a cordless screwdriver is defective and hence overheats the device. The insulation melts easily, the batteries are damaged and the cordless screwdriver cannot be used. A technical error cannot always be determined by external inspection and disassembly of the instrument is required.

Sequence of operations:

Diagnostics of the condition of power tools

Hot surfaces of the cordless screwdriver and battery indicate overheating of the tool. Overheating is a process that can occur in two cases. On the one hand, the screwdriver has an internal defect, and on the other hand, it is possible that it is being used incorrectly. To do this, before repairing, you need to check:

Screwdrivers are produced by a large number of companies; tools from Interskol, Bosch, and Makita are especially popular. They are usually extremely durable and reliable, however, individual parts may wear out. For example, when the drill does not work when you pull the trigger. Such a breakdown indicates that the trigger (button) does not work. Replacing the trigger is a fairly simple operation. Before starting repairs, the battery must be removed to prevent injury when the engine is engaged. The procedure for replacing the regulator using the example of a charger for a Bosch screwdriver:

Another type of repair with a Bosch screwdriver, for example, or from another well-known manufacturer is required much less frequently and is best entrusted to a service center.

Cordless screwdrivers are quite reliable these days, so it's actually hard to find any failures on the 18V model. Lithium-ion batteries have excellent battery life and low self-discharge rates, making tools equipped with them a regular choice in the home.

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

Nowadays, models are available 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 look at the standard charger circuit.

Charging circuit

The standard electrical circuit of a screwdriver charger includes a three-channel type microcircuit. In this case, four transistors are required for the 12 V model. They can vary quite a bit in terms of capacity. In order for the device to cope with high clock frequencies, capacitors are attached to the chip. They are used for charging both pulse and transition type. In this case, it is important to take into account the characteristics of specific batteries.

Thyristors themselves are used in devices to stabilize current. Some models have open-type tetrodes. They differ in current conductivity. If we consider modifications for 18 V, then there are often dipole filters. These elements make it easy to cope with network congestion.

12V modifications

A 12 V screwdriver (circuit 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 ensured at a level of 9 microns. To prevent the clock frequency from increasing sharply, capacitors are used. Resistors in models are mainly used as field resistors.

If we talk about charging on tetrodes, then there is an additional phase resistor. It copes well with electromagnetic vibrations. The negative resistance of 12 V chargers is maintained at 30 ohms. They are most often used for 10 mAh batteries. Today they are actively used in models of the Makita brand.

14V chargers

The charger circuit for a screwdriver with 14 V transistors includes five pieces. The microcircuit itself 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 charging parameters, then the current conductivity in the circuit, as a rule, fluctuates around 5 microns. On average, the resistor capacitance in the circuit does not exceed 6.3 pF.

Direct charging current loads of 14 V can withstand 3.3 A. Triggers are installed in such models quite rarely. However, if we look at Bosch brand screwdrivers, they are often used there. In turn, in Makita models they are replaced by wave resistors. They are good for voltage stabilization. However, the charging frequency can vary greatly.

Circuit diagrams for 18 V models

At 18 V, the charger circuit for a screwdriver involves the use of only transition-type transistors. There are three capacitors on the microcircuit. The tetrode is directly installed with a grid trigger used to stabilize the limiting frequency in the device. If we talk about charging parameters at 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 brand, then they use transceivers with increased conductivity. In this case, the maximum current load parameter can reach up to 6 A. Finally, mention should be made of 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 "Intrescol"

The standard charger for the Interskol screwdriver (the diagram is shown below) includes a two-channel microcircuit. All capacitors are selected for it with a capacity of 3 pF. In this case, transistors for 14 V models are used of the pulse type. If we consider modifications for 18 V, then you can find variable analogues there. The conductivity of these devices can reach up to 6 microns. In this case, the batteries are used on average 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 ensured in the region of 6 microns.

All this allows you to remove the load from the transistors. The tetrodes themselves are of the open type. If we talk about 14 V modifications, then chargers are produced with special triggers. These elements allow you to cope perfectly with the increased frequency of the device. At the same time, they are not afraid of online surges.

Devices for charging Bosch screwdrivers

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

Triggers in devices are used only at 12 V. If we talk about the protection system, then transceivers are used only of the open type. On average, they can carry 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 14 V modifications, 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, models on the market are presented at 12 and 14 V. If we consider the first option, then the transistors in the circuit are used of the pulse type. Their current conductivity is no more than 5 microns. In this case, triggers are used in all configurations. In turn, thyristors are used only for 14 V charging.

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 12 V charger.

Application of 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. You can most often find regulators of this type in models of the Bosch brand. They are not suitable for 12V chargers directly. 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 the pulse type. Triggers for regulators can be used. There are three diodes in the circuit. If we talk about 14 V modifications, then tetrodes are only suitable for them of the wave type.

Using BC847 transistors

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

The triggers themselves are of the open type, and their current conductivity is at the level of 5.5 microns. A total of three transistors are required for charging at 12 V. One of them is installed near the capacitors. The rest in this case are located behind the reference diodes. If we talk about voltage, then 12 V charges with these transistors can handle overloads of 5 A.

Transistor device IRLML2230

Charging circuits with transistors of this type are found quite often. The Intreskol company uses them in 14 and 18 V versions. In this case, the microcircuits are used only of the three-channel type. The direct capacity of these transistors is 2 pF.

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