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I spotted this during a discussion and decided that it was worth $6.49 to check it out. 24/20-pin ATX Computer PC Power Supply Bench Top Power Board Module Adapter. Turns out it's a very handy way to get a boatload of DC power for your bench or for powering multiple layout accessories and lights. You can have a load of 12VDC, 5VDC, and 3.3VDC for anything that's compatible for peanuts. The binding posts accept wrap-around wires or banana plugs.  The ground is common for all the voltages.  It also works equally well with 20 or 24 pin PC power supplies.

Many of us have a couple of old PC chassis or power supplies laying around, and if you don't, chances are a friend does. Add this little board, and you have an instant powerful power supply. This P/S was from an old Dell that I scrapped, and it's just a 250W supply, but for absolute peanuts, you can have larger supplies. The fuses are all 10A, but obviously can be changed for any value you see fit. Flip the switch and you have power, couldn't be easier.

You'll notice the "clean" look with only one connector coming from the power supply. Since I didn't plan on this ever going back into a PC, I cut all the other wires off while I had the top off to drill for the mounting.

Benchtop Power N1Benchtop Power N2

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Dave Zucal posted:

Thanks for sharing, John. Here is a very cool, 12 volt DC, Distribution Board that can be used with it to spread the 12 volt side over a layout. What is cool about it, it takes spade type fuses that if one blows an LED will light up under the blown fuse.  Item: #G22395, $10.00 Electronic Goldmine.   G22395Bhttp://www.goldmine-elec-produ...fo.asp?number=G22395

Price went up a bit!

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gunrunnerjohn posted:

Yep, I do realize that, but I knew this one was the standard ATX pinout as I was using it with a standard ATX MB when it was in use.  I never got bit by that one, but I did hear about it.

I got three of those power supplys. I just "wacked" the connectors off and hardwired

them to terminal blocks. Not as  "clean" but hey, it works.

Thanks for the info.

Joe

gunrunnerjohn posted:
Dave Zucal posted:

Thanks for sharing, John. Here is a very cool, 12 volt DC, Distribution Board that can be used with it to spread the 12 volt side over a layout. What is cool about it, it takes spade type fuses that if one blows an LED will light up under the blown fuse.  Item: #G22395, $10.00 Electronic Goldmine.   G22395Bhttp://www.goldmine-elec-produ...fo.asp?number=G22395

Price went up a bit!

Sellers often put an absurd price on items when their out and expecting more in. Keeps them from having to kill their ads and reposting when new stock arrives

SANTIAGOP23 posted:
Martin Derouin posted:

I just wired a rectifier to my AC transformer so I would have DC when needed...

Marty

SAME

You guys are missing the point.

What GunrunnerJohn has suggested is a separate and independent source of very cheap DC power. Putting a rectifier on your AC transformer will certainly provide some DC power, but you are drawing it from the same AC transformer that may be close to maxed out just powering the trains you run. This method avoids that problem and provides a source of very clean, smooth and heavily filtered DC power for the other needs you may have on your railroad.

Thanks Rich, you saved me the trouble of explaining it.   Many (most?) people probably have a dead PC around with a working power supply that will supply at least several hundred watts of pure DC power, so the cost is just a few bucks for the handy binding posts, fuses, and connections to the supply.  Putting a rectifier on your transformer will either yield half-wave DC for a diode or full-wave DC that does NOT have a common ground with the AC.  Lots of times, you would want filtered DC power, more expense.  Finally, this supply puts out a known voltage, having a rectifier and maybe a capacitor for filtering puts out a variable voltage based on load.

On the question of spacing for dual banana plugs, the terminals are NOT correctly spaced to use those, bummer.

Yep, black is common DC ground for all the voltages.  The -12V and -5V are negative in respect to DC ground, they're typically low power outputs.  On many supplies, there is no -5V, that's an optional output.  For instance, my supply has no -5V, the -12V is a 1A maximum current output as well.  The +5SB is the standby power, it's available even when the supply is off unless the main power is also off.  That powered the startup circuits on the motherboards for the soft power-up.

gunrunnerjohn posted:

Yep, black is common DC ground for all the voltages.  The -12V and -5V are negative in respect to DC ground, they're typically low power outputs.  On many supplies, there is no -5V, that's an optional output.  For instance, my supply has no -5V, the -12V is a 1A maximum current output as well.  The +5SB is the standby power, it's available even when the supply is off unless the main power is also off.  That powered the startup circuits on the motherboards for the soft power-up.

 Gotcha. Probably should take those speakers out too. Who knows what might come up where I'll use/need em

Per the thread title, another low-cost source of DC power is a 12V DC "brick" which you may have lying around from a consumer gadget...or buy one for less than 10 cents per Watt.  For example, from a previous OGR thread:

12v dc fixed output us plug with screw adapter 10 cents per watt

Many bricks and wall-warts use the coaxial-barrel style connector.  In above, seller supplies a "free" adapter to screw terminals though you can buy them for 50 cents or so on eBay.

If fooling around on the bench before committing an accessory/lighting to the layout room it's handy to measure the current.  Yes, you can use a DMM but for $3 (free shipping) you can wire up a DC combo volt-current meter - no soldering.  These meters have been discussed many times on OGR.

dc combo meter

The key is it's simply two-wires in, two-wires out.  Self-powered, compact, and for $3 (free shipping from Asia) I think a nice add-on even for the ATX breakout board.  Since they operate from 4.5V to 30V DC it could be used for the 5V output or the 12V output.

 

 

gunrunnerjohn posted:

This one appears to have the altered spacing Stan mentioned, it may be compatible with the dual banana plugs.  Maybe people asked for it?

24/20-pin ATX Computer PC Power Supply Bench Top Power Board Module Adapter GW

Those look like 20mm (length) fuses...and the connector spacing within a pair look a tad under the fuse length so it probably is the dual-banana "standard" spacing of 0.75" (19.05mm).

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  • 12v dc fixed output us plug with screw adapter 10 cents per watt
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Last edited by stan2004

That adapter looks and sounds great! You couldn't buy the parts and build it yourself for that, less than $7 and free shipping! So what if it's economy shipping, I'm in no hurry for it right away. I'm going to order two of them. I have one good used PC power supply Delta DPS-225HB A   for one and I know my brother-in-law has got to have one kicking around his stash of computer parts, then I can have one for the layout and one for the testing station. both in development modes so far. Thanks John!

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