The main function of the power switching circuit is to turn the lithium battery to the USB power supply and save the data when the system is shut down. The power switching is shown in Figure 4. In the figure, when the external power is turned on, V is high level to turn on the transistor Q2, and the base of Q1 is pulled low to make it turn on. The external power supply V is supplied to the microcontroller circuit and USB via the diode D1 (VC). Since the program sets POWER high at the beginning, Q2 is also turned on at this time. When the system is turned off, V goes low and transistor Q2 turns off. However, since Q3 is turned on at this time, Q1 is still turned on, but the data is saved by the lithium battery at this time. At this time, the timer l of the single chip starts to work, and after a delay of 10 s, The output of POWER is made low, which causes Q3 to turn off, and eventually the base of Q1 goes high, and the entire recorder is turned off.
Tin Zinc Antimony Copper Alloy Wire
It was made by Tin,Zinc, Antimony and Copper,Have a good metal characteristics.
SZSC is an alloy wire with Sn-Zn-Sb-Cu,Aproper amount of improvement elements are added to the tin zinc based alloy to inhibit oxidability. Various studies show that the current speed can be reduced.improve the performance of the alloy and wire is wildly applied with high cost performance.
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