12vdc 10 minute Off-Delay timer - Need help please.

Thread Starter


Joined Dec 7, 2008
Hi folks.

I'm new to this whole forum posting lark so please be gentle with me. From reading a ton of different posts within these forums, I reckon that you clever guys here are likely to be able to help me solve this.

Project brief:

To create an off-delay circuit for an external cooling solution for an Xbox 360 games console.

Basically, I have an Xbox 360 console which used to have a problem with the 3RLOD, I decided to remove the stock heatsinks and install a Koolance external water cooling system. This has remedied the fault with the console superbly (the console now operates at a max. load temp. of 43 deg. C.) and the 3RLOD hasn't returned in over 6 months of use since the mod was completed.

The issue which I have however, is that the external cooling solution must first be powered on from it's own seperate 12vdc power supply before the console can be powered on, aswell as having to remember to also switch off the cooling solution once I have had enough of getting my butt kicked at Halo3 by some grotty little 5yr old. I am concerned that either I might forget to do this one day or somebody else will come along and have a play but forget to turn on the cooler, which will most certainly lead to my Xbox 360 burning out.

I would like to create a circuit whereby upon powering on the Xbox 360, an off-delay timer circuit of some sort, fed from the Xbox 360's internal 12v supply, switches & holds on the seperate 12v supply to the cooler using a latching relay, then upon powering down the Xbox 360, the circuit will hold in the seperate 12v supply to the cooler for an additional 10 mins or so to allow it time to dissipate any residual heat from the system. I have read in places about using a 555 timer but i'm unsure exactly how to accomplish this.

Although the Xbox also operates using 12vdc which can be used to power the circuit, the seperate 12v supply must feed the cooler. I wouldn't like to run the risk of overloading the Xbox 360's PSU.

I would be very appreciative of any help that you guys could offer.

Thanks, WinMXer.


Joined Mar 24, 2008
No problem guy, we can talk you through it. Start by looking at this, then let us know where you need help. I assume you can read schematics, which is going to be pretty needed for this thread.

Thread Starter


Joined Dec 7, 2008
Hi Bill.

Thank you very much for the link to the schematics that you posted. You are clearly very well educated in electronic circuit design. I on the other hand am fairly crappy at circuit design, but can competently translate the information from a schematic onto a single layered pcb.

If it isn't too much to ask, please could you help me to construct a suitable timing circuit to suit the brief above using a 555 IC?

I would be sincerely appreciative of any help that you could offer.


Joined Dec 16, 2008
Did he ever get back to you? I need the exact same thing, not for an XBOX, but I need a 12v 555 timer set up for 10 minutes to close a relay and I have no idea how to do it.