Recommend three better flashlight charging circuit diagrams

Three better flashlight charging circuit diagrams:

In the above circuit diagram, three diodes of VD5-VD7 and R2 have two green and red LEDs to form a charging current constant current circuit. The charging current is constant as I=(the voltage drop voltage of three diodes between AB - single The forward voltage drop of the LED is /R2, where the forward voltage drop of the three diodes of VD5-VD7 is used when a low voltage Zener diode is used. RP is the charging voltage (battery voltage value detection adjustable resistance), adjust the RP to make the battery full battery voltage just turn on the transistor VT, pull the voltage of point A to 0V, point B voltage because there are three diodes VD5-VD7 Reverse blocking, so it is not affected. Since the triode VT is turned on to pull the voltage at point A to 0V, the charging is automatically stopped at this time. At this time, the battery is discharged through the red light emitting diode and the R2 and the triode VT. When the voltage is lower than a certain voltage, the triode VT is turned off, and the power supply is turned off. The battery is constantly charged by R2 and green LEDs and VD5-VD7 three diodes.

When charging, the green LED emits light; when the battery is fully charged, the red LED emits light.

If the capacitor is stepped down to a transformer step-down in the circuit (but for a rechargeable flashlight in which the housing is completely insulated with plastic, this is not very important because people cannot touch any part of the circuit) or in A A suitable voltage regulator diode is connected between the point and the ground (the negative terminal of the charger output), and the circuit is more reasonable.

Although the following two pictures are also relatively good, the circuit in which the charging function is simply too simple is similar to the simple charging circuit in the commercially available ordinary simple charging flashlight. Therefore, I personally are not very optimistic about the latter two circuit diagrams, and like the first circuit diagram is simple and practical.

The third circuit diagram below is an improved circuit of the second circuit diagram.