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Can you split a PWM signal without needing to boost it?

Metalshark
By Metalshark
in Cooling
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Go to solution Solved by deadaccount69,

You are correct in assuming it's simply a control signal. The first 2 pins are power, the third is a tachometer(it pulses every time it makes one rotation) and the 4th is a control signal for a little transistor across the motor power. You should be able to simply splice it with no problems.

Posted

Can you just attach the PWM signal to multiple fans?

 

Presumably it's a low power control signal. Using a multimeter on a Phobya 8 way PWM splitter it seems they've wired up all pins apart from the tachometer to all the fans. The tachometer is wired up to just one fan.

 

Does the PWM signal need a boost if splitting it between, say 4 fans or is it just fine to splice the wires?

 

Please note I'll be powering the fans another way.

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If your fans dont draw to much power, there shouldnt be a problem. On my Asus board a single fan connector can power 12w (12v 1a).

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  • Solution

You are correct in assuming it's simply a control signal. The first 2 pins are power, the third is a tachometer(it pulses every time it makes one rotation) and the 4th is a control signal for a little transistor across the motor power. You should be able to simply splice it with no problems.

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Just now, Admiraldeamlich said:

If your fans dont draw to much power, there shouldnt be a problem. On my Asus board a single fan conector can power 12w (12v 1a).

Thanks - the 12v and ground will be powered another way. Am specifically asking about the PWM signal wire.

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Just now, Metalshark said:

Thanks - the 12v and ground will be powered another way. Am specifically asking about the PWM signal wire.

my board didnt broke with 6 fans.

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Note: The reason why it uses a second control pin to turn off the motor power as opposed to just pulsing the main power line, is because the brushless motor actually requires a microcontroller to switch the coils at the right time. The microcontroller has a certain "boot up" time so turning it on and off constantly would make the fan behave erratically. That's why the microcontroller stays on permanently and just the power for the coils themselves are pulsed. That said, the power is still drawn from the main power leads as I said in my previous post. It's just a transistor switching the coils.

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