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[killzer]

I recently bought a new Chevy Silverado with the rear entertainment package and for a 400 mile trip I decided to hook up my 360 for the kids. This worked okay but not great.
The problems started with the inverter I already had, an el-cheapo 200 watt inverter. This inverter created an ungodly amount of line noise, to the point I had to mute the audio and the video had all kinds of squiggly lines running through it. So before even leaving town I stopped by the Auto Zone and bought a brand new $80 400 watt inverter. It still had line noise but only on the audio and not nearly as bad. The problem this one had was that it would shut off the Xbox when ever I killed the engine, the fan was stupid loud and the fuse blew on the way back home (it wasn't rated properly).
When I got back home I decided that there must be a better way so I hopped on the old interwebs to look for a solution. After deciding that $400 was way to much to spend on a Sine wave inverter I started thinking... Why should i convert the 12 Volt DC power from my truck to 120 Volt AC just to convert it back to 12 Volt DC again? The answer, I shouldn't have to.
After a little bit of digging around I determined that I can build an in vehicle 360 power supply with a high current wide input adjustable auto buck boot converter, a 3 Amp wide input 5 Volt buck converter (for the standby power that allows you to turn your xbox on via the wireless controller) and a small control circuit to switch it between standby and on (the same as the original power supply does).
The whole unit will be about half the size of the original 120 Volt AC power brick and will create less heat, no noise, and can keep the xbox running with the engine off. (it will run off anything between 2.5 and 30 volts DC) The total output capacity will be around 250 watts so it will be fully capable of running any version 360, phat or slim. I will soon be ordering the parts that I need to build this thing (at least the ones I can't get from the local Radio Shack) and my total build cost is $54. I will update this thread with pics as soon as my parts arrive and I start putting them together. If anyone has any questions or suggestions, input is always welcome.
To keep you all interested until my parts arrive, here is my parts list and a circuit schematic:

Adjustable DC-DC Auto Boost Buck Converter $30.99
5V DC-DC Buck Converter $5.00
Project Enclosure $5.49
12VDC/40A SPST Automotive Relay $5.99
NTE3222 - Optoisolator $2.28
NTE2519 High-voltage NPN Transistor $1.04
1N4001 Micro 1A Diode $1.49
NTE QW056-10 - 1/4W 56 Ohm Resistor $1.44
   
Total $53.72



And here's a link to open the schematic in the simulator I created it in so you can see it run.

[killzer]

At 200 Watts I don't want to run the risk of current pushing it's way thru to the 5V rail. That and the 3322 Optoisolator can be driven with significantly less current than the 2519 Driver Transistor. But yes, it should still work. I just wanted to over-engineer it rather than run any risks. If you do want to go with your revised design you won't need the 56 Ohm resistor, that was only there to drive the Optoisolator.

[killzer]

It's a protection diode. When you energize a relay it builds up energy in the coil. When you release it the energy stored in the coil floods backwards thru the circuit. The protection diode allows the current to flow in a circle thru the coil until the energy dissipates, protecting the rest of the circuit from the surge. You should always use a protection diode on a relay whenever sensitive electronics are involved.

Open up the simulation and increase the current speed. You can watch the current spin thru the coil when it releases.

[Bandit5317]

Apparently this isn't an issue with Killzer's Silverado, but for anyone else thinking of doing this, I just looked up the maximum current draw from 12v accessory lines and it's usually only 10-15 amps. That's fine for slim Xbox 360s or Jaspers, but it may be a problem for Falcons or especially for Xenons. Even if pulling more than 10-15 amps doesn't blow a fuse, it may be a fire hazard, so try this at your own risk.

[killzer]

QUOTE(Bandit5317 @ Apr 15 2013, 03:25 PM)

Apparently this isn't an issue with Killzer's Silverado, but for anyone else thinking of doing this, I just looked up the maximum current draw from 12v accessory lines and it's usually only 10-15 amps. That's fine for slim Xbox 360s or Jaspers, but it may be a problem for Falcons or especially for Xenons. Even if pulling more than 10-15 amps doesn't blow a fuse, it may be a fire hazard, so try this at your own risk.

My truck (being a bad-ass Chevy) is rated at 25 Amps per socket group (two sets of two sockets) so it's not an issue for me but yes, most cars are only rated at 10 to 15 Amps total so on most vehicles you will probably want to wire it directly to the battery with an in line 25 Amp fuse. (You should do this when running it off an inverter too) Even on my bad-ass Chevy, I still plan to hard wire it. I probably should have specified that in the original post but silly me, I thought it would be kind of a common sense thing.

[thr4773r]

Hi killzer,
Just adding an entry to see how the parts were coming together.

I had been working on car 12v power supply problem for a little while myself, and was getting ready to build a regulator from components using a modified version of the circuit here. I would rather find a pre-built buck/boost converter, and the one you show seems to fit the bill.

I figure by now, the parts should have made it in from china, and you may have had some opportunity to play with the power supply.

If so, have you had any problems with insufficient power being available or any other potential issues?

Wanted to check your results before chasing this solution on the same path as you.

Thanks.

[tryintomod]

For those that are limited at 10A, simply run a line to the battery and install a an inline fuse.

Very interesting. Please post up your results and the box you end up putting it all in (eye candy photos).

[greenmodder]

I am also very interested in this. Please post progress and pics!!