The mobile phone is charged with a 5th battery for emergency charging of the mobile phone, regardless of the occasion and time. The device is retailed in supermarkets, electronic markets, etc. It is an aluminum alloy case and the price is about 10 yuan. Figure 1 is an electrical schematic diagram, Figure 2 is a movement assembly diagram, both are patches, and Figure 3 is a shape. 
Figure 1 circuit schematic 
Figure 2 movement assembly drawing 
Figure 3 outline working principle: ICl step-up switching power supply chip is patch-shaped, the model is not common. The output square wave is sent to the Ql field effect switch tube for amplification, and is connected to the power source V1 through the energy storage inductor L1. When the switch Q1 is turned on, Ll stores energy; when the switch Q1 is turned off, L1 releases the electric energy, and is boosted to several times the power supply voltage through the boosting diode D1, and then compared with the error of the sampling resistors R1 and R2 to make Vout stable. At around 6V, it is used for emergency charging of power off mobile phones. C4 and R4 are absorption loops.
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