Post by blackknight on Mar 2, 2009 5:56:38 GMT
HackJoe, I did use a dual radiator in the beginning, but as I am sure you've now seen in my Mac Pro gallery thread that I switched to a triple rad mounted on the back. This allowed much more airflow in the case which provides better cooling for the HDDs, Northbridge and CPU.
bb, it was a very simple circuit, but I'll tell you how I did it. Go to your local electronics parts store (eg Radio Shack if you have it) and pick up a LM317t-ADJ voltage regulator. It shouldn't cost more than $3.00 US. Then build the circuit using the diagram listed on the back of the box (if you don't have a diagram on the box, google "LM317T-ADJ datasheet" and you should get the application diagram). I personally used 100 ohm resistors for both R1 and R2 and skipped the capacitors since they are being provided with stable 5V power anyways. Then, connect the 12V, GND, and Sensor signal wires to the fan like you normally would. Use a wire going to the 5V wire on a molex plug and run it to Vin on the voltage regulator. If you hook it up like the diagram in the datasheet, you will have 2.5V leaving the Vout pin of the regulator.
Another simpler method (which I haven't tried, but should work) is to just use the two 100 ohm resistors and build a voltage divider. Put the two resistors in series, connect 5V to one end of the resistors and GND to the other end. Then connect a wire in between the two resistors and connect that to the fan where you previously had 5V connected. Since the two resistors are both equal, each one has 2.5V across it and so the wire in the middle does as well.
*EDIT*
Since I have found this solution, I wanted to let people know that you can use different values of R1 and R2 to make a different divider. If for example, you want 3.75V or 1.25V, you could use 150 ohm and 50 ohm values for R1 and R2, switching them to get the two different voltages. You could also use a ~200 ohm pot instead of the resistors and get a variable effect.
bb, it was a very simple circuit, but I'll tell you how I did it. Go to your local electronics parts store (eg Radio Shack if you have it) and pick up a LM317t-ADJ voltage regulator. It shouldn't cost more than $3.00 US. Then build the circuit using the diagram listed on the back of the box (if you don't have a diagram on the box, google "LM317T-ADJ datasheet" and you should get the application diagram). I personally used 100 ohm resistors for both R1 and R2 and skipped the capacitors since they are being provided with stable 5V power anyways. Then, connect the 12V, GND, and Sensor signal wires to the fan like you normally would. Use a wire going to the 5V wire on a molex plug and run it to Vin on the voltage regulator. If you hook it up like the diagram in the datasheet, you will have 2.5V leaving the Vout pin of the regulator.
Another simpler method (which I haven't tried, but should work) is to just use the two 100 ohm resistors and build a voltage divider. Put the two resistors in series, connect 5V to one end of the resistors and GND to the other end. Then connect a wire in between the two resistors and connect that to the fan where you previously had 5V connected. Since the two resistors are both equal, each one has 2.5V across it and so the wire in the middle does as well.
*EDIT*
Since I have found this solution, I wanted to let people know that you can use different values of R1 and R2 to make a different divider. If for example, you want 3.75V or 1.25V, you could use 150 ohm and 50 ohm values for R1 and R2, switching them to get the two different voltages. You could also use a ~200 ohm pot instead of the resistors and get a variable effect.
