Reef Angel Forum

I've read a few posts over the last few days while researching the Reef Angel and it looks like there are at least a couple of people here using the PWM ports to control 12v PWM fans.

Right now I have a wall wart powering 2 x 80mm and 2 x 140mm fans with your standard 3 wires - black, red and yellow. I believe this is the old style PWM (not really PWM) fans. Ideally I'd like to control the fans on a PWM port(s) to lower the RPMs and reduce the noise level a bit when the temp isn't that high and ramp accordingly.

For those of you running fans on your PWM port I'd like to ask what type of PWM fans you're using. Are you using the true PWM 4-wire fans? How are you wiring them up? Are you tapping into the 12v feed to the PWM module (if you have the add-on module) or are you using a wall wart?

I'm assuming I need to get the true, 4-wire, PWM fans but I want to make sure I'm not overlooking something simple here.

Thanks,
Charlie

The 3pin fans don't have PWM control.
The 3rd pins is actually a tacometer, which is basically generates pulses for every rotation and you could count the pulses to find out what speed it is at, but you can't control.
The 4pin fan is the one you are looking for. Those are PWM controllable.
You will need it's own power supply to power the fans and make them all share the same ground. I recommend not sharing the power source from the dimming module to avoid noise in the dimming module coming from the fan motors.

I'm just looking into this myself and have the 4-wire pwm fan, but reading the fan spec shows that the expected pwm signal is 0-5v, not 0-10v as delivered on the std dimming module (I need my 5v channels for lights ).

Is this a problem ?

From a wiring perspective, I know +12v and GND, but what do the sense (green) and control (blue) wires connect to ? I'm guessing that the control is PWM+, but don't know about the sense (GND ??).

You made me go look at my setup, man
I've been feeging 10V for the past year or 2 and seems to be fine. lol
Maybe the one I'm using just accepts the 10V, who knows??
The control goes to PWM channel and sense is the tacometer I refered. Since we are not measuring speed, just leave that floating (not connected anywhere).
You can always use a voltage divider with 2 resistors of same value to drop the voltage down to 5V if necessary.

rimai wrote:You made me go look at my setup, man
I've been feeging 10V for the past year or 2 and seems to be fine. lol
Maybe the one I'm using just accepts the 10V, who knows??
The control goes to PWM channel and sense is the tacometer I refered. Since we are not measuring speed, just leave that floating (not connected anywhere).
You can always use a voltage divider with 2 resistors of same value to drop the voltage down to 5V if necessary.

Sorry

Nice idea on the divider, I presume something around 10k would be appropriate ? Out of interest, how many mA is the signal ?

PS. Got the vga cable today, thanks !

Yes, 2 resistors of 10K is good enough.
The RA can output up to 40mA