Hello, I was attempting to get a 5V output from a computer and into a transistor to trigger an external circuit. Presently I am attempting to use the serial output but I just cant get it. Would really appreciate any advice. thanks am
There is very little power available at the serial port, it was not designed for powering anything. PS/2 and USB ports do have +5V power available; do not load more than 300mA. You do not need any power (of merit) to trigger an external circuit, or to drive the base of a transistor; 10uA is more than enough for most devices and some will draw only a few microamps at most. You need to be mor eXplicit about what you are trying to do and how. For example, do you want to use an RS-232 output to turn something on and off? A CMOS gate has zero loading and might be part of a solution.
If you're trying to control something, parallel ports are more commonly used for this: http://www.hut.fi/Misc/Electronics/circuits/parallel_output.html
David & Robert, thank you for your reply. The link actually answers most of my questions. thank you Amit
