Is this safe? Home made 12v/5v switcher

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bledd

bledd

Don
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http://bleddyn.co.uk/forums/ocuk/switchv.png
WRONG WRONG WRONG

Thinking of buying a 3 pin on/off switch, wiring up 12v to one side, black to the middle and 5v to the other side.

I can solder it all myself, I will only be modding an extension cable, not the actual PSU molex.

Is this 100% safe? :o
 
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-actually, just thought about it. This is terrible, I'd just be combining the 12v and 5v lines and the switch would do nothing.

A 3 pin switch only works for 'on/off'
 
Thanks

Is this how I'd wire it..?

fanswitch2.png
 
Infact, to be fair, you could take GND out of the equation all together. God knows why I'm overcomplicating using DPDT.

Wire the GND directly to the fans, and have an SPDT (single pole double throw) switch wired up so that it switches between 5 and 12v.

2i24yfd.jpg
 
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Ok, thanks, so the centre pin on a 3pin switch is the 'output' line, and the outer pins are the red/yellow cables..
 
Yep, I'd double check with a multimeter (or a battery and LED if you don't have a multimeter), but typically that's the right pinout for a SPDT switch.
 
Right, I think what I need is a momentary SPDT switch button. It needs to be a button as I've got a case door.

Momentary = it has two positions that it can hold, yes?
 
What about a variable resistor and small dial, like a store bought item? I have a link to the instructions but not sure if the site is allowed here

Edit: as above you don't want momentary unless you want to make the circuit more complicated
 
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