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Dc power supply small automatic switching power supply

Dc power supply small automatic switching power supply
The switching power supply can not only charge automatically, but also has the compensation function of the negative temperature characteristic of the dc power supply. Its working principle is: when just connected to the charging source, due to its low terminal voltage, the voltage at both ends of the capacitor C is also low, not enough to trigger SCR2 conduction, and SCR2 is turned off. At this time, the current from D1→R1→R4→D2→SCR: control pole, SCR: conduction, power supply is charged. As the charging process continues, the voltage at the end of the capacitor increases, and so does the voltage at both ends of the capacitor C. When the charging voltage reaches the preset value, the c-terminal voltage also reaches the trigger voltage of SCR2, making SCR2 switch from the shutdown state to the on-off state, then the control pole current of SCR1 is zero, SCR1 switch off, and the charging stops.

Ac current stabilized switching power supply of dc power supply
The principle of ac current stabilized switching power supply is simple, and the step-down rectifying part is omitted. A 555 time - base circuit is used to form a self - excited multivibrator. D1, D2 and filter capacitor C2, C3 constitute a voltage doubling rectifier circuit, its output sent to the input end of the three-terminal voltage stabilizer 7805, composed of 7805, R5, D3, ac current steady current source to generate a constant charging current to charge the power supply. If the components are selected according to the parameters shown, the charging current of the circuit is 50mA, which generally takes 14 hours to charge.

Automatic battery charging device
The charging device is consistent with the principle of most automatic switching power supplies, that is, when the battery reaches a predetermined output voltage, it will automatically stop charging to prevent overcharging. . Resistor R1, R2, diode D1 and regulator tube DW constitute the buck rectifier regulator circuit; The charging circuit is composed of BG and D-, etc. Charge the battery slowly. At the beginning of charging, the terminal voltage of the battery is lower than the preset value and SCR stops. When the battery terminal voltage reaches the predetermined value, SCR will be triggered and the triode BG will be cut off. The charging process will automatically end and the signal H will be on. The predetermined value is determined by the resistance of R1.
| release time:2019.10.26    Source:
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