I think one point here is that it can cause insufficient small wiring to burn on the low voltage side. Sufficient size wiring is needed, if you are going to pull anywhere near the rated current on higher amperage outputs. Just because the voltage is lower don't be tricked into thinking that the high current output isn't an issue. As mentioned previously, fuses can help.
Engineer Jeff NS Nut Visit my layout at: http://www.thebinks.com/trains/
jbinkley60 wrote: I think one point here is that it can cause insufficient small wiring to burn on the low voltage side. Sufficient size wiring is needed, if you are going to pull anywhere near the rated current on higher amperage outputs.
I think one point here is that it can cause insufficient small wiring to burn on the low voltage side. Sufficient size wiring is needed, if you are going to pull anywhere near the rated current on higher amperage outputs.
Dr. Frankendiesel aka Scott Running BearSpace Mouse for president!15 year veteran fire fighterCollector of Apple //e'sRunning Bear EnterprisesHistory Channel Club life member.beatus homo qui invenit sapientiam
steamnut wrote:I consider myself to be moderately understanding of basic electronics, but this post has brought up something I've never completely understood.Why don't these power supplies (total rated power 83 amps) vaporize your house wiring fuse curcuit?And similarly, why is it that I can string a bunch of street or house lamps of 1.5 or 3v and my regulated 12v supply (using voltage regulators as well, or dropping resistors) can power significantly more of them than I would have thought from adding up the milli-amps?
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hopovo wrote:Did this string start with instructions on "How To"? How do you use the supply - Are the color/voltage of wires consistent with every power supply?
The configuration of one AT computer supply is typically the same as the next AT supply. Same goes for ATX.
Here's this link I posted above to an online tutorial. This mod requires opening the case and making modifications inside. It uses a resistor rather than a bulb to create the load. ATX, (switching) power supplies require a load or they will power down. AT supplies, (non switching) will run without a load.
http://web2.murraystate.edu/andy.batts/ps/POWERSUPPLY.HTM
BlueHillsCPR wrote:...ATX, (switching) power supplies require a load or they will power down. AT supplies, (non switching) will run without a load...
CSX Robert wrote: BlueHillsCPR wrote:...ATX, (switching) power supplies require a load or they will power down. AT supplies, (non switching) will run without a load...AT and ATX power supplies are both switching, and both need a minimum load(there are actually some AT and ATX power suppies that have an internal load so that they do not require a minmum external load, and there are also some that will run without a load, but not regulate the power well).
I wasn't aware that was the case. I have had AT power supplies that would run without load. I have never experienced that with an ATX so far though. My apologies if I have made an erroneous statement. I was under the impression that AT supplies were not switching types. I guess the power supplies I have seen run without load must have had an internal load. Thanks for clarifying that. My bad.
To whom it may concern, I have removed the information that I posted earlier on how I converted a PC power supply for use as a power supply for model railroad use do to the lack of interest. While the power supply can be modified without opening the case and without using a power resistor. Some people may not understand how to do this. If you wish to contact me I will be more then happy to explain to you how "I" went about doing this using an "ATX" power supply.
Please NOTE that I did not have to open the case!
My thoughts on power.
As I began reading an article on how to convert a computer power supply into a cheap or even free bench power for electronics a thought began to creep into my mind. You see I have always been a tinker of sorts, I love to challenge of taking something and making it into something else entirely or taking something broken and fixing it. That is way I see using a computer power supply not for testing electronics but as a power source in general.
I know that there are a few that can see where I am leading. If something brakes you try and fix it before you take it to someone else. You hate to throw anything away, you hate to pay good money for something you yourself can repair. I myself grow up working or playing with every piece of junk or some gismo I had found.
Now if you would like to use and old computer power supply you have laying around or order a new one on-line to use or would rather use wal-warts or buy of the shelve that is up to you. I had a power supply laying around that I had ordered off-line and did not want to just chunk it into the trash. While I did have to open the case to repair the blown fuse in a brand new power supply I enjoy doing this kind of thing.
But with that said, you do not have to open the case to perform the mod needed to use the PC power supply. All can be done from the outside!
I have a working demo unit sitting on my layout bench right now. The mod is very simple to perform.
Items needed:
One PC power supply (new or used)one 1157 automotive bulb,one soldering iron and solder,one volt-ohm meter for testing,one hour of your time.
To begin, lay the PC power unit on a table. Locate the 20 pin connecter that is normally plugged into the motherboard. Next find the sense wire (this should be a brown wire). Local a black wire (this is your ground). Local a red wire (this is a +5 volt power supply wire).
Solder your ground (black) wire to the bulb case along with the sense (brown wire). Solder the red (+5volts) wire to both contact *** on the bottom of the bulb. By using both elements of the bulb you ensure that you have a current drew the fools the unit into thinking it is inside of a PC and you will have full output voltage to all of the PC power supply power wires. But by using a +5volts feed to a 12volts bulb the bulb itself only gets warm and should not be any problem.
The color code for the wires is: Red = +5V, Black = Ground (0V), White = -5V, Yellow = +12V, Blue = -12V, Orange = +3.3V, Purple = +5V Standby, Gray = power is on (not used), and Brown = Sense wire.
You do not have to open the case!You do not have to do this mod!You do not have to use this information!
It is up to you, do as you will.
Johnnny_reb,
Thanks for posting the text version of your power supply mod! I was sorry to see you had removed your pictures too. I didn't perceive a lack of interest in what you had done...I hope I did not give that impression in any way.
Thanks again!
This thread came at the perfect time...my local club is thinking about redoing the wiring under the layout. Right now, each town along the line is powered by its own power supply. We were thinking of finding a single power supply and running a power bus around the layout to power structure lights, animation, etc.
I think this will fit the bill nicely!
Robert Beaty
The Laughing Hippie
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Johnnny_reb wrote: My thoughts on power.As I began reading an article on how to convert a computer power supply into a cheap or even free bench power for electronics a thought began to creep into my mind. You see I have always been a tinker of sorts, I love to challenge of taking something and making it into something else entirely or taking something broken and fixing it. That is way I see using a computer power supply not for testing electronics but as a power source in general.I know that there are a few that can see where I am leading. If something brakes you try and fix it before you take it to someone else. You hate to throw anything away, you hate to pay good money for something you yourself can repair. I myself grow up working or playing with every piece of junk or some gismo I had found.Now if you would like to use and old computer power supply you have laying around or order a new one on-line to use or would rather use wal-warts or buy of the shelve that is up to you. I had a power supply laying around that I had ordered off-line and did not want to just chunk it into the trash. While I did have to open the case to repair the blown fuse in a brand new power supply I enjoy doing this kind of thing.But with that said, you do not have to open the case to perform the mod needed to use the PC power supply. All can be done from the outside!I have a working demo unit sitting on my layout bench right now. The mod is very simple to perform. Items needed: One PC power supply (new or used)one 1157 automotive bulb,one soldering iron and solder,one volt-ohm meter for testing,one hour of your time.To begin, lay the PC power unit on a table. Locate the 20 pin connecter that is normally plugged into the motherboard. Next find the sense wire (this should be a brown wire). Local a black wire (this is your ground). Local a red wire (this is a +5 volt power supply wire).edit: after locating the about wires cut them from the 20 pin connecter.Solder your ground (black) wire to the bulb case along with the sense (brown wire). Solder the red (+5volts) wire to both contact tips on the bottom of the bulb. By using both elements of the bulb you ensure that you have a current drew the fools the unit into thinking it is inside of a PC and you will have full output voltage to all of the PC power supply power wires. But by using a +5volts feed to a 12volts bulb the bulb itself only gets warm and should not be any problem.edit: I would however mount the bulb in such a way as to give it breathing room and make it replicable should it ever blow.edit: On the unit I built I added a chassis mounted fuse holder into my case. Basically because the unit was new but had a blown fuse. But with the low cost of a new unit you may opt out just to replacement the unit instead of doing any repair work requiring you to open the case.The color code for the wires is: Red = +5V, Black = Ground (0V), White = -5V, Yellow = +12V, Blue = -12V, Orange = +3.3V, Purple = +5V Standby, Gray = power is on (not used), and Brown = Sense wire.You do not have to open the case!You do not have to do this mod!You do not have to use this information!It is up to you, do as you will.Photos added
edit: after locating the about wires cut them from the 20 pin connecter.
Solder your ground (black) wire to the bulb case along with the sense (brown wire). Solder the red (+5volts) wire to both contact tips on the bottom of the bulb. By using both elements of the bulb you ensure that you have a current drew the fools the unit into thinking it is inside of a PC and you will have full output voltage to all of the PC power supply power wires. But by using a +5volts feed to a 12volts bulb the bulb itself only gets warm and should not be any problem.
edit: I would however mount the bulb in such a way as to give it breathing room and make it replicable should it ever blow.
edit: On the unit I built I added a chassis mounted fuse holder into my case. Basically because the unit was new but had a blown fuse. But with the low cost of a new unit you may opt out just to replacement the unit instead of doing any repair work requiring you to open the case.
Arjay1969 wrote: This thread came at the perfect time...my local club is thinking about redoing the wiring under the layout. Right now, each town along the line is powered by its own power supply. We were thinking of finding a single power supply and running a power bus around the layout to power structure lights, animation, etc.I think this will fit the bill nicely!
As for a wiring bus I would use three or four of the same color wires from the power supply to the terminal strip so as not to stress the wiring from the power supply to the strip. From the terminal strip forward I would use wiring of 20 to 16 ga. just so the bus would be able to support the load running its full length with as little voltage drop as possible.
CSX Robert wrote:I just want to point out that if you are using an AT(instead of ATX) power supply, the motherboard connector will not have a brown sense wire(this is the signal that tells the power supply to turn on).
As I am color blind I had to go with a pin count and not rely solely on the color. One article said it was brown another said green. But without this wire hooked up the units output voltages were half of what it should have been. In an earlier post someone posted a link to an article about this conversion and in the text look for the word "TIPS" highlighted in some shade of blue, this work is a link to another page where you will find a drawing of all connecters and a pin count with each wires corresponding color and function. I found it very useful.
Up to this point I have used an AT type power supply because there's no external load requirement to activate it. With the info in this thread I now know how to activate an ATX supply without having to attach a heavy resistor to it. I also don't have to read through a bunch of technical info. That would drive my dyslexia wild.
Johnnny reb: I didn't know you're color blind. So am I. Blue and shades of gray. I can see light gray and dark gray, the shades in between appear as silver or black.
if you are using an ATX supply, you can force it to turn on my shorting the GREEN (ATX_PWR) wire with any of the black (ground) wires in the 20-pin plug. The BROWN wire is only used by the power supply if you have WoL, or WoK enabled on the motherboard in your PC (that's Wake on LAN and Wake on Keyboard, respectively).
Best way to do this when jury-rigging things to work is with a paperclip... however a momentary contact SPST switch (which can be salvaged from a dead computer even) should work, unless your PSU is one of the annoying ones that needs to continually have the power circuit closed... however this is usually only found on computers that come prebuilt from a manufacturer (Dell, HP, IBM, etc).
Note, this assumes you're using an ATX supply from a post-OEM dealer (such as antec or thermaltake) an OEM dealer (such as dell, etc) from after about 1997 or so, when the ATX supplies were *finally* standardized with colors (OEM mfg's pre 1997 used either brown or green in the PSU's as far as I can tell)
-Dan
Builder of Bowser steam! Railimages Site
NeO6874 wrote: Note, this assumes you're using an ATX supply from a post-OEM dealer (such as antec or thermaltake) from after about 1997 or so, when the ATX supplies were *finally* standardized with colors (OEM mfg's and pre 1997 PSU's used either brown or green as far as I can tell)
Note, this assumes you're using an ATX supply from a post-OEM dealer (such as antec or thermaltake) from after about 1997 or so, when the ATX supplies were *finally* standardized with colors (OEM mfg's and pre 1997 PSU's used either brown or green as far as I can tell)
Assuming this how does one tell if it is a unit made after 97?????????
Sorry guys,
Was talking about if the *computer* was made after 97 by a mfg (Dell, HP, etc). Got a phone call halfway through the post and spoke mistakenly (it has been corrected in that post). far as I can tell, the major replacement mfg's had all standardized on the ATX colors almost right away.
Best way to tell this on a computer is that the activation code for windows will be a sticker affixed to the case somewhere (generally windows 98SE). Microsoft hadn't used stickers until 98/99 with the release of win 98SE (everything prior to this was those easily loseable Certificate of Authenticity cards)
Hi again, and I'm still alive!! Many thanks to Johnny_reb - it works! It's so great to have somewhere to go to for help. Now, about my hair loss...........
Bob from Britain
P.S. Only for S.P. fans: did you know Intermountain are making an AC12 in N for release at Christmas!
bob from britain wrote: Hi again, and I'm still alive!! Many thanks to Johnny_reb - it works! It's so great to have somewhere to go to for help. Now, about my hair loss...........Bob from BritainP.S. Only for S.P. fans: did you know Intermountain are making an AC12 in N for release at Christmas!
Dear Bob sorry about the hair loss, glad the thread has helped you.