Mobile phone charger

According to the author, the original 220 V voltage is removed through the capacitor step-down and diode rectification part, and the 12 V vehicle plug of the car lighter is connected with the 12 V input terminal in the figure, with normal output of 4.2-5 V / 1a.


Moreover, the author emphasizes that if the output voltage is slightly lower than the charging voltage of the user's mobile phone, it is only necessary to adjust the optocoupler current limiting potentiometer RP properly, so that the appropriate charging voltage can be obtained.

We can see that this circuit is a relatively simple self-excited power supply, which controls the output voltage through the conduction and cutoff of VT1 and vt2, and the optocoupler is also set in the circuit for output voltage feedback.

First of all, the car's cigarette lighting hole provides 12V voltage to the input end of the power supply. After passing through the rectifier bridge, one way is sent to the collector of VT1, C2, R5, through TR and VT1, The three parts D5 constitute a peak absorption circuit, but the voltage here is only ten volts, so this circuit is not of great significance here; the other circuit is added to the base of VT1 through R1 to provide a starting current for VT1.

When the voltage of C3 reaches a certain value, vt2 will turn on, VT1 will turn off, and C3 will discharge. When the voltage of C3 drops to a certain extent, vt2 will turn off, and VT1 will turn on. In this way, the switching power supply on the primary side is formed.

Because it is a car charger, the function of the optocoupler here is to prevent the output short circuit.

Generally speaking, the modification of the charger is only used for entertainment research. If it is used, 80% of the components are useless, which leads to the very low efficiency of the charger. I'm afraid it will damage the battery of the car. Moreover, there are hidden dangers in the charger. According to the author, if the 12V of the cigarette lighting hole is directly connected to the output end, then if the output voltage of the charger is low If the input 12V is short circuited, then the charger has no protective effect, which will directly lead to the charger short circuit, increase the current, spontaneous combustion, and even more serious, short circuit of automobile battery.

According to the author, the original 220 V voltage is removed through the capacitor step-down and diode rectification part, and the 12 V vehicle plug of the car lighter is connected with the 12 V input terminal in the figure, with normal output of 4.2-5 V / 1a.

Moreover, the author emphasizes that if the output voltage is slightly lower than the charging voltage of the user's mobile phone, it is only necessary to adjust the optocoupler current limiting potentiometer RP properly, so that the appropriate charging voltage can be obtained.

We can see that this circuit is a relatively simple self-excited power supply, which controls the output voltage through the conduction and cutoff of VT1 and vt2, and the optocoupler is also set in the circuit for output voltage feedback.

First of all, the car's cigarette lighting hole provides 12V voltage to the input end of the power supply. After passing through the rectifier bridge, one way is sent to the collector of VT1, C2, R5, through TR and VT1, The three parts D5 constitute a peak absorption circuit, but the voltage here is only ten volts, so this circuit is not of great significance here; the other circuit is added to the base of VT1 through R1 to provide a starting current for VT1.

When the voltage of C3 reaches a certain value, vt2 will turn on, VT1 will turn off, and C3 will discharge. When the voltage of C3 drops to a certain extent, vt2 will turn off, and VT1 will turn on. In this way, the switching power supply on the primary side is formed.

Because it is a car charger, the function of the optocoupler here is to prevent the output short circuit.

Generally speaking, the modification of the charger is only used for entertainment research. If it is used, 80% of the components are useless, which leads to the very low efficiency of the charger. I'm afraid it will damage the battery of the car. Moreover, there are hidden dangers in the charger. According to the author, if the 12V of the cigarette lighting hole is directly connected to the output end, then if the output voltage of the charger is low If the input 12V is short circuited, then the charger has no protective effect, which will directly lead to the charger short circuit, increase the current, spontaneous combustion, and even more serious, short circuit of automobile battery.