Hi tried googling it but got lost, so say I have a couple of led or rgb 120mm fans and want them to run slower, well if they were standard fans I would usually put 5 or 7 volts through them but what could I do with the ones with led's (this is outside a pc case)
what happens to fan led's when fan speed turned down
- Thread starter RobTi
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RGB LED fans usually have their fans running off a separate cable. The cheap crappy single colour LED fans just get dimmer if you reduce voltage.
Soldato
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It depends on the wiring - if you're lucky, RGB fans will have a separate +12V line (or +5V line if addressable) for LEDs. Then the usual ground, +12V, tach and maybe PWM wires for the fans themselves. As mentioned, simpler one-colour LED fans are often sharing the +12V and ground wires so lowering voltage can lead to less or no light.
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Most typical LED's have a forward bias (turn on) voltage of around 2.2V, so even with a very low supply they would likely still light to more or less the same level, though you may notice a slight reduction in the amount of light emitted. This is of course subject to any current limiting resistor that might be used to reduce the current draw of the LED, but you will likely still be ok with a lower voltage.