Structure POWER!

[doneldon]

How about a TRS80 Color Computer with 16K RAM and a cassette tape serial drive?  140MB floppies were available, or a 20 Meg hard drive for $2000 ($100/Meg).  Compare that to a current 500 Gig hard drive for $129, $0.00026 per Meg!!!  And then there was the Timex-Sinclair.

[Johnnny_reb]

 

POST REMOVED!

 

[hopovo]

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?

[trainnut57]

For all of us out here too afraid to show their computer ignorance, I say HUH???????????????????????????????????????????????????????????????????????????

[CSX Robert]

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?

You can get 83 amps out of a computer power supply without vaporizing the house wiring because the power supply does not draw 83 amps on the input side because of the step down in voltage.

For example, if you have a 12 volt power supply supplying 10 amps, it will only draw 1 amp on the 120 volt side. The input and output wattage have to be equal(not really equal because no power supply is 100% efficient). Watts = volts * amps, so in my 12 volt example, 12 * 10 = 120 * 1.

For the power supply Johnnny_reb was talking about: watts = 3.3V * 28A + 5V * 38 + 12V * 17A = 92.4 + 190 + 204 = 486.4 watts, so it is probably a 500 watt power supply. On a 120 volt circuit it would draw 500 / 120 = 4.17 amps(again, this is not counting for losses in the power supply).

[jeffrey-wimberly]

 

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. 

How right you are. The smallest wire I use to my structures and such is 22 gauge.

[jbinkley60]

 

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.

  

[jeffrey-wimberly]

Are you thinking amps or watts. The computer power supply I'm using puts out 150 watts at 10 amps. That will (and has) pull a lot of lights.

[BlueHillsCPR]

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?

Are you saying you have a 120 volt step-down power supply that is delivering 83 Amps? 

[steamnut]

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?

[Johnnny_reb]

My thoughts on power supplies for structures,

So let say each structure on a club layout has 5 30ma bulbs and the layout has a total of 100 structures. That makes for a total of 15,000 bulbs. Just eleven computer power supplies would be more then enough to supply the power needs of the whole layout structure lighting system.

You might want to check your math here: 5 x 100 = 500 not 15 000!

Thank you for pointing that out my "OP" has been edited.

[BlueHillsCPR]

My thoughts on power supplies for structures,

So let say each structure on a club layout has 5 30ma bulbs and the layout has a total of 100 structures. That makes for a total of 15,000 bulbs. Just eleven computer power supplies would be more then enough to supply the power needs of the whole layout structure lighting system.

You might want to check your math here: 5 x 100 = 500 not 15 000!

That could make a difference to the draw!

[modelmaker51]

My thoughts on power supplies for structures,

So let say each structure on a club layout has 5 30ma bulbs and the layout has a total of 100 structures. That makes for a total of 15,000 bulbs. Just eleven computer power supplies would be more then enough to supply the power needs of the whole layout structure lighting system.

You might want to check your math here: 5 x 100 = 500 not 15 000!

[UpNorth]

Now that is way cool.  And I've got a slew of these binding posts, toggle switches sitting around doing nothing.  Now I can kick myself for wasting power supplies. Must have got rid of at least 6 of them. Well at least I have ONE left over and they are dirt cheap.

[BlueHillsCPR]

One of the better tutorials I have seen for converting an ATX computer supply for use with a layout.

http://web2.murraystate.edu/andy.batts/ps/POWERSUPPLY.HTM 

[Johnnny_reb]

Upnorth and Jeffrey thank you for your comments. I would like to add one more thing, with the power wires protruding from the computer power supply case (this is the normal factory arraignment) "ALL" wiring modifications can be done "WITHOUT" opening the power supply. Besides the "ALL" PC power supply comes with a build-in fuse so that if you should overload the unit by putting more of a current drew on it then it can handle or if you should short out the any of the power wires the fuse will blow and save your PC (or layout). 

The only PC power supplies that I have had go bad or blow the fuse have all been my fault.

But for the sack of clarity in this thread I will try and build a demo this weekend and post the results along with a step by step how-to of how I built the interface wiring.

[jeffrey-wimberly]

I find it extremely easy to use the computer power supply. No sense in using a lot small transformers that eat up more power than one large one would and like UpNorth said you can power everything on the layout with it.

[UpNorth]

Turns around and walks away shaking his head.

I know, I know..  They would rather spend $15.00 for .5A to power 30 Tortoise instead of spending $10.00  to power ALL the Tortoise, all layout building lights and what ever else they can  throw at it.  And since  the AC side is in a sealed enclosure that you simply plug a molded cable to, little to no danger of catching one big AC shock. 

Basicaly what you are getting is something similar to the Digitrax PS2012 that sell for 150$.

Walk this way !...   

[Johnnny_reb]

Turns around and walks away shaking his head.

[fwright]

The Commodore 128 had dual 5 1/4" floppy drives and 2 megs of ram! State of the art!!

Nothing to do with the thread topic, but the Commodore 128 had but 128K of RAM, hence its name.  Similarly, the Commodore 64 had 64K of RAM.  The disk drives for the C64 were stand-alone 5.25" units (140K each disk) that operated off a proprietary bus, that the C128 also used.  I don't remember whether my C128 had an integral disk drive or not, but I know I used 3.5" 720K floppies with it.  Also, got a 1200 baud modem, instead of the 300 baud with the C64.  The biggest improvement was the 80 character display (640x480) instead of 40 characters.  Cooking with gas!  In 1993, I upgraded(?) to an Amiga.  Finally, in 1997, I bit the bullet and bought into Windows.

Still have memories of writing Unix scripts and Pascal and Fortran programs to run on the Vax's at Purdue with my C64, all from home with the 300 baud modem.  Them were the days.

Fred W

meanwhile back to the topic... 

[superbe]

Circuitron recomends the following wall wart which is also available from Radio Shack. I don't know what the cost is but for me it would be simpler than a computer power supply to install as it is basically plug and play. Having already experienced two "good shocks" in my life time I do as little wiring as possible. If I can't see it I don't fool with it.

110 volt AC wall plug adapter outputs filtered 12 volts DC at up to 500 milliamps of current. Sufficient to power up to 30 TORTOISE^TM Switch Machines.

Something similar for lights with a 10/12 volt resistor as mentioned by Lothar should do on my size layout.

Bob

[Johnnny_reb]

My thoughts on power supplies for structures,

One amp = 1000ma

The three power outputs I plan to use on the computer power supply.

+3.3V at 28 amps output divided by a 30ma (load)  =  933 lights bulbs

+5V at 38 amps output divided by a 30ma (load)   = 1,266 lights bulbs

+12V at 17 amps output divided by a 30ma (load)   =  566 lights bulbs

                                                                   Totals = 2,765 lights bulbs

By dividing the total output amps of each power output, then divide by half again a computer power supply can easily power 1382.5 30ma bulbs at a 50% load on the power supply.

A one amp wall-wart run a full capacity can supply only 33.3 30ma bulbs and would need a total of 41.56 wall-warts to supply the same amount of bulbs as the computer power supply. Run it half capacity and you would need 82 wall-warts just to match the power output of the computer power supply. Wow at two wall-warts per outlet I would need 41 outlets. And I don't have 41 electrical outlets in my whole house let alone the train room.

So let say each structure on a club layout has 5 30ma bulbs and the layout has a total of 100 structures. That makes for a total of 15,000 bulbs. Just eleven computer power supplies would be more then enough to supply the power needs of the whole layout structure lighting system.

So one computer power supply ordered off the internet at say $20.00 each. Now add in the home engineering for the terminal blocks, computer power splits just to get you to the point of layout wiring. Lets say another $10.00 and the cost of using a computer power supply has jumped to say $330.00 total. Verses 82 wall-warts at $10.00 each for a total of $820.00 plus terminal blocks $3.00 each. For a total of more then $823.00.

My time to build the layout lighting system (oh wait that's with either system). The cost of supplying power is $0.022 per bulb building the computer power supply interface system and $0.055 per bulb with the wall-warts and inter face system.

So that's $30.00 verses $60.00 or more. I'll be using a computer power supply to meet my power needs. The way I see it, for my small layout one computer power supply and I'm good to go.

Now the output amps are the max rating of that power outputs. The power supply that I'm getting these numbers from is a "Hercules switching power supply" for an "ATX" mother board. The unit is rated at 500 watts max output. While you may think this is over kill, I bought the unit to replace an older unit after rebuilding my computer and blow the fuse in the old power supply. (fuse replaced)

But promptly blown the fuse in it also.(that's another story) But if you use splitter cables you can hard wire the unit just as you would any wall wart and it would be a plug and play replacement if it should even need replacing. The cost to me is free as I will replace the blown fuse and already have the splitter cables. BTW splitter cables make good jumper cables for a modular layout. No need to cut wires if you should need to move the module.

Also, if you prefer to use wall warts that is you option. I have a few sitting around myself. I'm just a Scrooge MacDuck when it comes to saving money and wanted to let people know what the capabilities were of a computer power supply. One or two centrally located would be able to meet most peoples layout power needs and being a switched unit only one switch to turn off the layout lighting when I'm not running the layout.

+3.3V could power Leds or structure lighting

+5V could power Leds or structure lighting

+12V could power Tortoise switch machines, Leds and structure lighting.

Maybe MRR would be interested in doing a story on layout power options? I could build a demo unit.

[loathar]

I have a question relating to power supplies so I guess it's ok to ask on this thread. When you use a wall wort do you just cut off the plug end of the electrical cord and wire it straight to a bus for the structures. I kwnow next to nothing about electricity so I have to be very carefull. And Lothar, I believe the Comodore was one of the more advanced computers of it's day.

Bob

Yes. Light bulbs don't really care about polarity but LED's do. Watch your voltage. LED's require around 3volts. Light bulbs can be from 1.5v. to 14v or more. You can use a 12v wal wart, just use resistors in line to step down down the voltage to what you need.

The Commodore 128 had dual 5 1/4" floppy drives and 2 megs of ram! State of the art!!

[jeffrey-wimberly]

In answer to your question, yes. Before I switched over to a computer power supply I used wall warts. I would simply cut the end off the cord and wire it directly to whatever I needed power for. And some Commodore 64's and 128's came with tape drives at the users option.

[superbe]

I have a question relating to power supplies so I guess it's ok to ask on this thread. When you use a wall wort do you just cut off the plug end of the electrical cord and wire it straight to a bus for the structures. I kwnow next to nothing about electricity so I have to be very carefull. And Lothar, I believe the Comodore was one of the more advanced computers of it's day.

Bob

[jeffrey-wimberly]

Graphics required too much memory in ASM applications to run on the 128 and basic programs with graphics ran too slow.

[loathar]

Since we are playing "Can you top this" I have stored away with the manual my son's first computer, a Radio Shack TRS 80 with a TAPE DRIVE. The monitor was built in the case as was the key board but don't ask mehow many megs are on a tape.. Some day it might be worth something.

 Bob

I remember those "trash 80's" I got a Commadore 64 with tape drive for a graduation present back in 83. I later got a Commadore 128. It had some kind of railroad program for it that was all text. No graphics.

[superbe]

Since we are playing "Can you top this" I have stored away with the manual my son's first computer, a Radio Shack TRS 80 with a TAPE DRIVE. The monitor was built in the case as was the key board but don't ask mehow many megs are on a tape.. Some day it might be worth something.

 Bob

[jeffrey-wimberly]

I can top  that. 10mb winchester MFM hard drives and assorted ram expansion cards that I can't for the heck of it remember the name of... They left last year in the "making room" blitz.

I actually had an IDE that was only 8mb! 

Dang! That's a dinosaur! And I thought the hard drive from my old Apple was small at 10mb.

[loathar]

I can top  that. 10mb winchester MFM hard drives and assorted ram expansion cards that I can't for the heck of it remember the name of... They left last year in the "making room" blitz.

I actually had an IDE that was only 8mb!