Professional answers:
1: Solar power generation panel, constant voltage 20V, you can choose the simplest 8V voltage regulator chip output to charge the battery.
2: The battery is 8V, 200mA output, visually it is a lead acid battery, what is its capacity? Generally, the mobile phone charging current of 500mA can meet the safety requirements.
3: Voltage stabilizer chip selection: L78M08? Voltage stabilization 8V, maximum output 500mA, the circuit is as shown below:
Vi is connected to the solar cell output, Vo is connected to the battery
< /p>Working principle?
Due to significant changes in sunlight during use, the internal resistance of solar cells is relatively high, so the output voltage is unstable and the output current is also low, which requires a cDC conversion ircuit to convert voltage to charge cell phone battery. The DC conversion circuit is shown in the figure. This is a single tube DC conversion circuit. form of an asymmetrical flyback converter circuit. When the switch VT1 is turned on, the induced voltage of the primary coil NP of the high frequency transformer T1 is 1 positive and 2 negative, the secondary coil Ns is 5 positive and 6 negative, and the rectifier diode VD1 is cut off -off state. At this time, the high frequency transformer T1 passes through the primary coil Np and stores energy when the switching tube VT1 is turned off, the secondary coil Ns is 5 negative and 6 positive, and the energy stored in the high. -the frequency transformer T1 is rectified by VD1 and filtered by the capacitor C3 before being sent to the load. ?