My tech store give me MPS3638A to replace pnp transistor, i think collector current is off, i dont know if to use it or if it not critical to its usage, plz advise.
Ok, for the DIY'ers out there not afraid of soldering, I have successfully dumped the liteon key using a HOMEBREW RS232 LEVEL CONVERTER, made from only 10k resistors, transistors, a 0.15uF capacitor, and a diode.
Follow this schematic:
Here's the changes I made to make it work:
1. Replace all 4k7 resistors with 10k resistors (so it uses only 10k resistors)
2. Replace the 100nF (0.1uF) cap with a 150nF (0.15uF) cap. The capacitor must be non-polarized
I used a 2n3904 and a 2n3906 transistors, and a standard zener diode
more info: http://picprojects.org.uk/projects/simpleSIO/ssio.htm