Open Island

I have few step down boards designed to provide 5V as USB ource, but I don't really use it these days. these boards having a bigger inductor than the cheap and small DCDC converter today These are small, and claim 2A, but if you use it to 1A continue, it would get hot pretty fast, on inductor, and the chip(the switching mosfet is in the chip.) The main chip on these old boards are MP2307 , data sheet claim to have 3A continuous. With these old board, the inductor is larger, should have better performance. Find the feedback resistor MP2703 use pin 5 as feedback pin, with a set of voltage divider, as R1 and R2 in the reference design. After few search, I found that the R2 (10K) is the R2 of reference design, which connect FB pin to ground. R6and R7 on my board is parallel connected as a R1 in reference design. Change the voltage divider resistors. In the data sheet, it shows how to calculate the out put voltage and some reference value.   I wish to use this board to power a plug form...

This is what I want to use as a display under sun shine.  https://github.com/MakersFunDuck/Common-Kitchen-Timer-With-LCD-Replacement-Board I found this kind of display on Taobau, there are few common contact, just like the segment LED idsplay. This vender provide me some info:  奇耘电子 Even with frequent questions   1、 液晶屏有反射模式、半透模式，还有全透模式，不知道有什么区别，该如何选择？       反射模式：下偏光片不透明，所以不能接背光使用，适用于白天或者有外界光源的场合，优点是对比度高一些；       全透模式：透过率约40%左右，必须配合背光使用（否则会看到屏下面的元件或者PCB），优点是背光亮度高；       半透模式：介于反射和全透模式之间，透过率约30%，是否接背光都可以使用，比较灵活。   2、LCD段码屏有静态驱动和动态驱动的，请问如何区分？       静态驱动：只有一个公共端COM，每个像素都是单独电极引出。优点是和动态驱动相比显示效果好一些，缺点是引脚多；       动态驱动：超过2个以上公共端COM，每个电极至少控制2个以上的像素，需要时间分割扫描方式驱动。   3、LCD段码屏可以采用直流驱动吗？和LED数码管的驱动有什么不同？         LED数码管：直流驱动，由公共端接在阳极或者阴极，有共阳或者共阴的区别；      LCD液晶屏：交流驱动，公共端和驱动端都需要加交流方波信号，依靠改变两者的相位来控制对应的像素是否显示，这个是和LED数码管本质的区别，所以没有共阴或者共阳的说法。绝不能把公共端COM直接接地，通过控制驱动端接高电平来显示，这样子长时...