Is it possible to slow down the D4?? got one off my mate for a project, tis a bit too loud for me... was hoping to slow it down. I heard its poss to run them at 7v.. Any ideas as to how??
Switch the pins around in the molex. Take the ground one and move it to where 5V is, then the difference between the two is 12V-7V=5V. [edit]Make sure you look on the pump's data sheet to be sure it's capable of running and starting at 7V though - wouldn't want it not starting on you once you'd done the switch.
It doesnt start at 5v... Was gonna try 7v but the write up on it had a warning about current or something going back into the psu through the 5v line....
That really shouldn't be a problem, UnkleRosco. We do it with fans all the time at work, the only PSU that doesn't like it is the Enermax Galaxy.
You could also rig it up through a switch so that it starts at 12v and then you switch it down to 7v when needed. Alternatively, like any 12v fan, you could also put it on a variable resistor to fine tune the speed for noise and flow. Reducing pump noise also has to do with how it is mounted and other factors you may want to address.
Fans use practically no current though, so its not too much of a problem. I'm not sure about doing it with a pump, as a D4 uses something like 1.4A. I would have thought it would be ok, but best to check these things. You need to be careful when switching things that take this much current. You'll need to either get beefy switches (as many don't have a very high DC current rating) or use a relay or something. You can't just put a D4 through a normal variable resistor like you can with a fan, it draws far too much current. You need to find one that can either take higher currents, or use something a little fancier to control the voltage. Beware fan controllers, as the power limit of many is below (<17W) that drawn by the D4. Also, some controllers use PWM, and I'm not sure how this will affect the pump. As regards noise, mounting can make a significant difference, but the D4 tends to emit that whining noise anyway as far as I am aware. Also, I tested a D4 at home on about 6V, on a supply limited to 2A. Often the pump wouldnt start as the current seems to spike initially to start it going, and it kept hitting the limiter. Not sure if this happens at 12V or to what extent. Might be worth testing, or at least bearing in mind.
