Bosch Screwdriver Battery Chargers
Many modern screwdrivers operate on battery power. Their average capacity is 12 mAh. In order for the device to always remain operational, a charger is required. However, they are quite different in voltage.
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 take a look at the standard charger circuit.
A standard screwdriver charger circuitry includes a three-channel type microchip. In this case, transistors for a 12 V model will require four. In terms of capacity, they can be quite different. In order for the device to cope with a high clock frequency, capacitors are mounted on the chip. They are used for charging both pulsed and transient type. In this case, it is important to consider the features of specific batteries.
Thyristors are directly used in current stabilization devices. Some models have open-type tetrodes. They differ in current conductivity. If we consider modifications to 18 V, then there are often dipole filters. These elements allow you to easily cope with network congestion.
Modifications to 12V
At 12 V, the charger for the batteries of a screwdriver (the diagram is 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 the level of 9 microns. To ensure that the clock frequency does not increase sharply, capacitors are used. Resistors in models are used mainly field.
If we talk about charging on tetrodes, then there is an additional phase resistor. He copes well with electromagnetic vibrations. Negative resistance with 12 V charges is maintained at 30 Ohms. They are most often used for 10 mAh batteries. Today they are actively used in brand models. "Makita".
14 V Chargers
The charger circuit for a screwdriver for 14 V transistors includes five pieces. Directly, the chip for converting current is suitable only for a four-channel type. Capacitors in models on 14 V 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 chip. If we talk about the parameters of the charges, then the conductivity of the current in the circuit, as a rule, fluctuates around 5 microns. On average, the capacitance of a resistor in a circuit does not exceed 6.3 pF.
Directly, the charging current loads at 14 V can withstand 3.3 A. Triggers in such models are installed quite rarely. However, if we consider brand screwdrivers "Bosch"then there 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 charging frequency can vary greatly.
Model circuits for 18 V
At 18 V, the charger circuit for a screwdriver involves the use of transistors of only a transition type. There are three capacitors on the chip. The tetrode itself is mounted with a diode bridge. To stabilize the limit frequency, a grid trigger is used 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 charging for company screwdrivers "Bosch", then this indicator 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 brand chargers "Interskol", then transceivers are used in them with increased conductivity. In this case, the parameter of the maximum current load can reach 6 A. In the end, mention should be made of the company’s devices "Makita". Many of the battery models are equipped with high-quality dipole transistors. They cope with increased negative resistance. However, problems in some cases arise with magnetic vibrations.
Video: Bosch Screwdriver Battery Chargers
Charging device "Intrescol"
Standard screwdriver charger "Interskol" (diagram shown below) includes a two-channel chip. Capacitors are selected for it all with a capacity of 3 pF. In this case, the transistors of the 14 V models are used pulse type. If we consider modifications to 18 V, then you can find variable analogs there. The conductivity of these devices can reach up to 6 microns. In this case, the batteries are used at an average of 12 mAh.
Scheme for the model "Makita"
Screwdriver Charger Diagram "Makita" has a three-channel type chip. There are three transistors in the circuit. If we talk about screwdrivers for 18 V, then in this case, 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 transistors. The tetrodes themselves are open type. If we talk about modifications to 14 V, then the charges are issued 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 network jumps.
Screwdriver Chargers "Bosch"
Standard Screwdriver Charger Diagram "Bosch" Includes a three-channel type chip. In this case, the transistors are pulse type. However, if we talk about screwdrivers for 12 V, then there are installed transitional analogues. On average, they have a bandwidth of 4 microns. Capacitors in devices are used with good conductivity. There are two diodes in the charges of the presented brand.
Triggers in devices are used only at 12 V. If we talk about the protection system, then transceivers are used only 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. Speaking separately about modifications to 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 model "Skill"
The Skil screwdriver charger circuitry includes a three-channel chip. 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 used pulse type. Their current reducibility is not more than 5 microns. In this case, triggers are used in all configurations. In turn, thyristors are used only for charges of 14 V.
Capacitors on 12 V models are installed with a varicap. In this case, they are not able to withstand large overloads. At the same time, transistors overheat quite quickly. There are three diodes directly in a 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 capacitance of 3 to 10 pF. It is most often possible to meet regulators of this type with brand models "Bosch". Directly for charging at 12 V, they are not suitable. 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 for them are suitable only for the wave type.
Using transistors BC847
The charger circuit for a BC847 transistor screwdriver is pretty simple. These elements are used most often by the company. "Makita". They are suitable for 12 mAh batteries. In this case, the microchips are of a three-channel type. Capacitors are used with dual diodes.
Triggers are directly used by the open type, and their current conductivity is at the level of 5.5 microns. In total, transistors for charging at 12 V will require three. One of them is installed at capacitors. The rest in this case are behind the reference diodes. If we talk about the voltage, then charging at 12 V overload with this transistor can transfer 5 A.
Charging circuits with transistors of this type are quite common. Company "Intrescol" uses them in modifications of 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 transfer current overloads from the network well. In this case, the conductivity index in the charges does not exceed 4 A. If we talk about other components, then the capacitors are installed pulse type. In this case, they will need three. If we talk about models at 14 V, then they have thyristors for voltage stabilization.