Posted by aramis on January 06, 2002 at 10:25:00:
In Reply to: Re: Grounding with different voltages? posted by aramis on January 06, 2002 at 10:10:59:
I just tried this using my PC power supply (5V), a standard LED, and a 2.2k resistor. It worked fine.
One note...if you use the PC power supply, the grounds might already be tied together through the PS/2 keyboard port(?).
: Hmmm...I'm thinking that you should be OK doing this, IF you tie the ground of the IPAC to the ground of the 5V power supply. This will eliminate the possibility of a ground loop, and reference the 5V potential correctly.
: And, you might want a resistor (say like 1K) in series with the LED to limit the current in the circuit (so you don't overload the 5V supply) and also to cut the voltage to the LED. I know you said they are super-bright, which might be designed to handle 5V, but double-check the rating...I think a standard LED can only handle like 2.2V.