Scheme of charger for screwdriver. Screwdriver charger circuitry

A lot of modern screwdrivers work from the battery. The average capacity is 12 mAh. To ensure that the device always remains in working condition, you need a charger. However, they are quite different in voltage.

Nowadays models are produced on 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 electric circuitry of the screwdriver charger includes a three-channel chip. In this case, transistors for a 12 V model will require four. By capacity, they can be quite different. In order for the device to cope with a high clock frequency, capacitors are attached to the chip. They are used for charge both pulsed and transient type. In this case it is important to take into account the specific features of specific batteries.

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

Modifications to 12V

The 12V charger for screwdriver batteries (the diagram is shown below) is a set of transistors with a capacity of up to 4.4 pF. In this case, conductivity in the circuit is ensured at a level of 9 microns. To ensure that the clock frequency does not rise sharply, condensers are used. Resistors for models are mainly used in the field.

If we talk about charging on tetrodes, then there is additionally a phase resistor. With electromagnetic oscillations, he does well. The negative resistance of charging by 12 V is maintained at 30 ohms. They are used most often for storage batteries for 10 mAh. For today they are actively used in models of the trade mark "Makita".

14 V Chargers

Scheme of the charger for screwdriver for 14 V transistors in itself includes five pieces. Directly, the current conversion chip is only suitable for a four-channel type. Condensers for 14 V models use impulse capacitors. If we talk about batteries with a capacity of 12 mAh, then there are additionally installed tetrodes. In this case, there are two diodes on the chip. If we talk about the parameters of charge, then the conductivity of the current in the circuit, as a rule, fluctuates around 5 microns. The average capacitance of the resistor in the circuit does not exceed 6.3 pF.

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

18 V models

At 18 V, the charger circuit for a screwdriver assumes the use of transistors of only a transient type. There are three capacitors on the chip. Directly the tetrode is installed with a diode bridge. To stabilize the limiting frequency, the device uses a grid trigger. If we talk about the charging parameters at 18 V, then it should be mentioned that the conductivity of the current fluctuates around 5.4 m.

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

Chargers "Intreskol"

Standard charger screwdriver "Interskol" (the scheme is shown below) includes a two-channel microcircuit. Condensers are selected for it all with a capacity of 3 pF. In this case, transistors for 14 V models are of the impulse type. If you consider the modifications to 18 V, then there you can find variable analogs. Conductivity in these devices can reach up to 6 microns. In this case, the batteries are used on an average of 12 mAh.

Scheme for the model "Makita"

Scheme charger screwdriver "Makita" has a chip three-channel type. There are three transistors in the circuit. If we talk about screwdrivers at 18 V, 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. Directly tetrodes are of an open type. If we talk about the modification to 14 V, then charges are issued with special triggers. These elements allow you to perfectly handle the increased frequency of the device. In this case, the jumps in the network are not terrible for them.

Devices for charging screwdrivers "Bosch"

The standard "Bosch" screwdriver charger circuitry includes a three-channel chip. In this case, the transistors are pulsed type. However, if we talk about screwdrivers at 12 V, then there are transitional analogues. On average, they have a bandwidth of 4 microns. Condensers in devices are used with good conductivity. There are two diodes in the presented brand.

Triggers in devices are only used for 12 V. If we talk about the protection system, then the transceivers are applied only to 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 the modifications to 14 V, they are produced under batteries for 15 mAh. Triggers are not used. There are three capacitors in the circuit.

Scheme for the "Skill" model

The Scil Screwdriver charger circuit includes a three-channel microcircuit. In this case, the models on the market are represented by 12 and 14 V. If we consider the first option, the transistors in the circuit are of the impulse type. The current reducibility in them is no more than 5 microns. In this case, triggers in all configurations are used. In turn, thyristors are used only for 14 V charge.

Condensers for 12 V models are installed with a varicap. In this case, they are not capable of withstanding heavy overloads. In this case, the transistors overheat quite quickly. Directly there are three diodes in charging at 12 V.

Application of LM7805 controller

Scheme of charger for screwdriver with regulator LM7805 includes only two-channel chips. Condensers are used on it with a capacitance of 3 to 10 pF. To meet regulators of this type most often you can have models of the trade mark "Bosch". Directly for a charge of 12 V they are not suitable. In this case, the parameter of negative resistance in the circuit reaches 30 Ohm.

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

Using transistors BC847

Scheme of charger for screwdriver on transistors BC847 is quite simple. These elements are most often used by Makita. They are suitable for 12 mAh batteries. In this case, the chips are of three-channel type. Condensers are used with dual diodes.

Direct triggers are used open type, and conductivity of the current in them is at the level of 5.5 microns. Total transistors for charging in 12 V will require three. One of them is installed at the capacitors. The rest in this case are behind the reference diodes. If we talk about voltage, then charging at 12 V overload with this transistor can carry in 5 A.

Device on transistors IRLML2230

Charge circuits with transistors of this type are quite common. The company "Interskol" uses them in modifications of 14 and 18 V. In this case, the chips are only three-channel type. The capacitance of these transistors is 2 pF.

Overload the current from the network they carry well. In this case, the conductivity index in the charges does not exceed 4 A. If we talk about other components, the capacitors are set to pulse type. In this case, they will need three. If we talk about the model at 14 V, then there are thyristors for stabilizing the voltage.