hi im developing pk2 lite programmer from blue room electronics i have a dough in the 5v supply it must be provided externally are it will be supplied by the usb. if we provide external power supply then usb 5v and external 5v will meet in a same point so there my be any damage to the system pls help me. and the diode bat41 & in5817 are available in the market? are else pls suggest any other alternate diode equivalent to that
Good that you imagined the danger of commoning the external 5V on USB.
you may have external power on the pcb by cutting the 5V track coming from PC side of USB.
ground of the power supply can however be common.
1N5819 are available locally in any large town, or you can order from shops in nearest industrial electronic shopper.For BAT41 also you can use 1N5819