I am trying to make a fanbus that has an on-off-on switch. I have somewhat of a schematic but i want an LED to be lit when its on 7v and lit even brighter when its on 12v. And i only want one Led. Thanks

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The very simplest would be a bicolour led and a DPTP switch. Red on 12v, green on 5v etc.



Pic courtesy of www.fanbus.com

If you really want the same colour light with varying brightness, use an SPDT switch, and just place the led in parallel with the positive and negative fan leads. Calculate resistance based on the the max voltage (12v). The light would be bright with 12v and dim with 5 volts (maybe too dim).

So your fan would be wired thusly:



And your LED would be spliced into the positive and negative fan leads (blue and black above) in the same fashion as the one below:



That last pic is just to show the position of the LED, it is only an SPST switch, and would not work for a 12v / 7v fan switch.

Let me know if that makes sense.

I just took a closer look at your schematic, I think it should work fine. As long as you claculate your resistor based on 12v.

ya that helped me alot thanks, im almost done with this case ive been working on it since march. should be done in 1-2 weeks.