DC: Multiple units vs amp draw

Here's an "instructable" for turning an Xbox 360 power supply into a 12VDC 12.1A power source.

http://www.instructables.com/id/How-to-turn-an-X-Box-360-PSU-into-a-12v-lab-PSU/

So, can it power a DC HO locomotive with a few parts of an MRC Railpower 1300?

[video]https://youtu.be/-i0SanOfbCw[/video]

Sort of!?! The speed seems slow. I'm going to have to buy a voltage meter to see what kind of output I'm getting. - Brandon

 

Keith,
That's because the guy in the video followed your directions exactly as you suggested. That was my video! I made it last night. That was top speed by the way, in both directions. It seemed to be about half as fast as the stock power pack would run it. Maybe not quite that slow. Anyway, I have to get a voltage meter to see what the output is. I was going to go by Walmart or Autozone this evening to pick one up, but after working registration and open house at school until 6:15pm, and with a 30 minute drive home ahead of me, a voltage meter just wasn't as important on my way home as my recliner was to me at that moment. If I don't pick one up tomorrow, then I will Saturday for sure. - Brandon

 

I purchased my first multimeter. It's an Etek 10709W http://manualsbag.com/wp-content/uploads/2014/09/41.jpg. I've read the manual but I still have some questions. My modified Xbox 360 power supply supplies 12.29VDC to my modified MRC Railpower 1300's AC terminals, but then, the power pack's DC output terminals only put out 10.05VDC at full throttle. I'm not sure why. Also, how can I use the multimeter to determine how much current my track is supplying?
- Brandon

 

Brandon, you purchased a really nice VOM. I'm looking to buy one soon and was wondering how much did it cost? Please keep posting information and questions on DC power systems. This thread has been very interesting. Right now I'm not able to afford a DCC system and would rather use that money on my layout track, buildings and scenery. Maybe at a later date I will change over to DCC.

Joe

 

Thank you Keith, I will check it out.

Joe

 

Joe, that's the same exact situation and mind set I'm in. I'm sure DCC is great, but DC is really enough for me at the moment. Therefore, like you, I "would rather use that money on my layout track, buildings and scenery." However, since I stumbled upon the xbox360 power supply in a yard sale, with it's listed output of 12V and (more importantly) 12.1A, I thought it might be the answer to having enough amps to run multiple locomotives together. So far, with the help of an instructable online, and with Keith's help, I've successfully modified the xbox PSU, modified my MRC power pack, and successfully operated a single locomotive on one section of flex track. The max voltage at the rails was only 10.05V. That's shy of the 12V I was hoping for, but my real concern is finding out how many locomotives it can move. Since I'm in a rebuilding phase, I may get out some old EZ-mate or Powerlocs track to go ahead and pile on locomotives in order to test out the xbox PSU's muscle. Maybe I will get a chance to try it out this weekend. Whenever I can get to it, I will do my best to post a video of the results. - Brandon

 

Keith, is there a particular video number you have in mind? I've seen a few but don't know if I saw the one you are referring to.

Brandon, what size of wire are you using. This is a major issue in current transmission. I read several years ago that the surface area can be used to describe current flow. I've used this theory ever since and have #22 on a loop circuit effectively making it a #18 wire. Have run up to four units on a very cheap transformer and homemade throttle with no problem on my previous N scale layouts.

Joe

 

I just performed another experiment with different/larger wiring. I used my brand new 3M test leads from Walmart http://www.walmart.com/ip/3M-Electrical-Connectors/36141658 to connect the modified xbox PSU to the power pack's AC terminals. The xbox PSU puts out 12.24VDC. At full throttle, I only got a reading of 10.00VDC at the DC terminals of the powerpack which is essentially the same result.

 

Well folks, this thread is probably already on it's way back to the vault. The Xbox360 PSU I attempted to use has a safety mechanism that shuts off power in the event of an electrical fault. Something as simple as trying to put a locomotive on the track triggers the safety feature. The only way to reset the Xbox360 PSU is to unplug it and plug it back into an outlet. I suppose installing a toggle switch in the power cord could be used to reset it but, simply put, that would be more trouble than it's worth. It's a shame. I was really looking forward to having those 12.1 amps it claimed to put out at my finger tips. Oh well. You never know until you try. I tried but the results were far less than desired. However, I'm not getting rid of the PSU as I may find another use for it as a 12VDC / 12.1A PSU down the road.
The final experiment wasnt' a total loss. It was actually a learning experience. I wanted to see if I could use test leads to connect the Xbox360 PSU directly to the track without the potentiometer or DPDT switch of the MRC 1300 power pack. I used a locomotive that I'm not that attached to as a guinea pig and plugged in the PSU. The locomotive ran fine, so I tried other locomotives. All of the locos that I tried ran fine. Of course I had no throttle or direction control but as long as I unplugged the PSU before railing a loco, the PSU ran each loco just fine with 12.24V to the rails. Prior to my experiment, I didn't know if a loco could run directly from a 12VDC source but I found out what I'm sure others already know... indeed DC locos CAN run directly off of a 12VDC power source. I can already hear folks saying, "I could have told you that."
Well that's it folks. My experiment lead me to the conclusion that an Xbox360's 12VDC / 12.1A PSU can be modified to power DC locomotives but not without major draw backs that prove to be more trouble than they are worth... even when using a potentiometer and DPDT switch. I considered researching a way to bypass the PSU's automatic shut-off feature but I figured Microsoft included the safety feature for a reason. With that in mind, I feel that having my house NOT go down in a blaze of glory is more important than the 12.1 amps I was hoping for. - Brandon

 

Brandon, Thank You for posting all your test results with the power supply. I applaud your efforts. It proves that no matter what you do in life always try new ideas. Just look at all the efforts Thomas Edison took to invent the light bulb. In the end it changed the world.

Joe

 

Well, I spoke too soon. Just days after that post, a co-worker gave me an old laptop power supply with an output of 15-16VDC, 5A. I wired it directly to my track and it ran a train (wide open, in one direction) quite well as expected. Now I want to know if I can add a potentiometer, DPDT switch, and an in-line fuse. If this can work, in what order (from power supply to track) should I install them? - Brandon

 

DC power packs can be had quite inexpensively and will work without any of the modifications you are having to make. This really might be a better approach so that you can get up and running without the risk of damaging something.

GS

 

Brandon, I made a throttle from plans in Model Railroader maybe ten years ago that you may like to build. It has a transistor, potentiometer, a couple of switches and two or three resistors packed in a small electrical box. A four or six conductor wire connects the throttle to layout. Overall it's a pretty simple project. I can't look for the plans tomorrow but will Tuesday and post what I can along with photos shortly after.

Joe