SparkFun Forums

[riden]

All of the parts referenced in Pete's and my post are commonly available. The most critical part is the choice of the power transistor.

Edit: Do you have a schematic for the aftercooler? Perhaps you could substitute a transistor for the relay with some minor modifications.

[Chip Douglas]

All of the parts referenced in Pete's and my post are commonly available. The most critical part is the choice of the power transistor.

Edit: Do you have a schematic for the aftercooler? Perhaps you could substitute a transistor for the relay with some minor modifications.

Yeah heres the link to the page:

http://rbjtech.bulldoghome.com/pages/rb ... cooler.htm

[riden]

Thanks for the link. The schematic uses a dual 555 for the timer and is pretty straight forward. I got the answers to a couple of questions that I had.

The first is whether or not the 5v standby can power the fans. The answer is no. In the design you referenced, the circuit is using a 9v rechargeable battery, so I suspect that the standby 5v is only sufficient to power the timer. Or perhaps the fans run too slow at 5v.

The second question was whether or not a transistor could be substituted for the relay. The answer is probably. However, the TWO fans are connected to GND all the time and the power is switched to them. You could use a PNP or P-Channel power MOSFET along with a couple of diodes to isolate the power for the fans from the XBox. You will also need a small signal NPN to invert the output of the 555.

The relay approach is the cleanest way. All things considered, I'd order a relay and go with that approach. Let me know if you need more information about the transistor switching approach. BTW, you could substitute two 555s instead of the 556 (if you can't get any), with the proper changes to the wiring of the pins.

[Chip Douglas]

Its alot to read, but if you read more toward the bottom of the page, he mentions that the fans can run off the 5 volts without the need of the 9 volt rechargeable battery, but we wanted the fans to move more air out faster, so thats why he used the battery.See the 360 has a built-in variable power to the fan connector,so it normally runs the fans @ 5v, as the 360 gets hotter it then auto adjusts to 7v, and 12v.Because mine is watercooled, it never gets hot enough to trigger the auto adjusting feature, so it normally would never go above 5 volts.Thats why i bypassed a transistor so the fan connector always outputs 12v.But it is way too loud, so i then reduced it to 9 volts.

As far as running the fans @ 5v after powering down, and adding a timer to run for 10 minutes....If a relay is the cleanest way to do this, then thats the route i will have to take.I was just hoping that i could substitute the 5v DPDT relay for one that is more common to find.Locally the only 5v relay i can get is a 5v SPDT , 5v SPST reed relay, or a 12v DPDT relay.Would it be possible to use two 5v SPDT relays, or somehow make a 12v DPDT relay work? Im gonna guess here and say that a 12v DPDT relay would require 12v to work? So going back to the rechargeable battery idea, I dont think they make rechargeable 12v batteries(besides the big box type) So maybe a 9v rechargeable and two AA rechargeable batteries to equal 12 volts could work?