Hi !! Probably an easy one ... but I'm not into electronics, so I must ask before I do something stupid ... I'm preparing to do some control panel wiring. I have some bi-colored leds that are gonna show to switches positions (feedback comes from a micro-switch mechanically connected to the turnout). My power supply is a computer power supply. I use the +5V connections from this beast. Right now, when connecting 2 of these leds, I use a 150 ohms resistor and the brightness is perfect. Question: There will be about 50 of theses leds later on the layout ... could that be too much for this 20amps power supply ? What I fear is that with each new led I connect, will all the others get a little darker ... until it barely shows ? Also: My feedback system uses +5V *AND* -5V from that power supply ... +5V mean switch is thrown, and -5V means switch is not thrown. The -5V output is only 0.5amps ... will there be a problem there, like the one I just stated ? Thanks !!! P.S.: Explanation of why I use +5V and -5V: With each turnout, a microswitch is mechanically connected to the switch machine... so when the turnout is operated, the microswitch "knows" the position of the turnout. There are 3 pins on these microswitch ( DPST) .. I send +5V on the outer pin, -5V on the opposite pin, and the switch sends me back +5V or -5V via it's middle pin depending on the turnout position. All I have to do is connect this "unknown" voltage to one side of a led, and the other leg to the power supply GND ... and voila ! The led light's up red or green accoring to the turnout position ! I fiddled a lot with this idea on my prototype borad (breadboard) and it gave great results ... I can't wait to see it in action on the control panel !!