Posted by aramis on January 06, 2002 at 10:10:59:
In Reply to: Grounding with different voltages? posted by rmfx on January 06, 2002 at 06:10:14:
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.
: I'm making an illuminated control panel using all microswitch pushbuttons from Happ. I've put super-bright LEDs inside the hollow cavity of the buttons, and everything looks great. What I'd like to do is use the normally-closed pole of the switches to cause the LED to turn off when the button is pushed (by cutting power to the LED), or even turn on a different colored LED while being held down.
: My question is, since I am using an IPac, and LEDs will have to be powered by an external 5v source (an AC adaptor or the PC power supply) can I just use the same ground that runs from the switches to the IPac, or do I need to run another ground back to the power supply?
: Thanks