X10 Community Forum
🔌General Home Automation => Automating Your House => Topic started by: bkenobi on December 29, 2012, 05:37:05 PM
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I'm going to be installing my Arduino attic fan controller in the near future. The project was put on the back burner so I could address other X10 issues, but now that those are dealt with and proven reliable, it's time to get the fan going again. In any case, i will be putting the controller in the attic and plugging it into an AC outlet for power. I was originally going to use an old cell phone charger, but after learning about X10 PLC noise issues, I won't be using a switching type. A quick search on ebay and Amazon found only switching power adapters. Does anyone have a line on a cheap power adapter for the arduino that is non-switching?
Requirements: 9 to 12V DC, 250mA or more, 2.1mm plug, center pin positive.
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I'm pretty sure I have some 12v DC 500ma inductive wall warts. You can have one if you pay shipping. PM me if interested.
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I went back to my stash and found the wall warts I pulled out last spring. Two of those were switching, but the last was not. That one is1.25A, 21mm, center pin positive. I tested it with my XTBM and XTB-IIR and found that without the adapter i had. 6.70v but. 9.99v with it plugged in.
So now I don't need an adapter right now, but an idea of how/where to source them down the road might be good. Search terms? Sites to check?
Oh, and thanks for the offer. I'll keep that in mind when the next project comes along in case you haven't found a use for them!
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I suggest you test its output.
There are two basic transformer run wall warts.
One uses a regulated output and would be fairly close to its rated voltage with a partial or full load.
The other is an unregulated type and its output would be close to its rated output voltage when loaded at its rated current.
A lighter load would result in a higher than rated output voltage.
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I checked the voltage when I was checking polarity and it reported right around 12v (maybe slightly higher). I plugged in the arduino and the light came on so i know it at least powers up.
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Good. Sounds like it is a regulated liner type.
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Almost all Arduino models have onboard regulators.
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So now I don't need an adapter right now, but an idea of how/where to source them down the road might be good. Search terms? Sites to check?
Oh, and thanks for the offer. I'll keep that in mind when the next project comes along in case you haven't found a use for them!
http://www.allelectronics.com/make-a-store/item/DCTX-1280/12VDC-800MA-WALL-TRANSFORMER/1.html
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That works. Thanks!
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I have a project that I now need a power supply for, but the link from AllElectronics is dead. Based on a recommendation from the Arduino forums, I'm looking for a 7.5-12v 1A power supply. For X10, I'd rather not rely on a filter so a non-switching type would be best. Can I assume that if the PSU says that it is 110/220v, that it will cause issues with X10? There are lots of units available that are both 110/220v, but not as many that are 110v only. Also, the Arduino needs a 2.1mm center positive connector. I can cut the wire and put on a different connector if necessary so that's not as critical as the power supply itself (though it would be nice to have a factory installed plug).
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Go to Amazon and search on 12v 1a 2.1mm and you'll turn up numerous candidates.
It's likely that any rated for 120V-240V are switching type but not all switching power supplies will cause X10 problems. Non switching types are disappearing because they tend to cost more.
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I saw quite a few matching that search on Amazon and Ebay but I noticed they all seem to say 110/220v. Since they all look alike, how can I tell if they will be an issue for X10 other than pure luck?
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I'm afraid luck is your only ally unless someone can recommend a specific model.
They use several different frequencies and not all pose a problem. Some may have filter caps across the mains to prevent leakage but these are a problem for X10. Without detailed specs or a schematic, you are left with luck.
I tested some from Circuit Specialists a few years back when switchers first became available but I have no idea whether they still carry the same model. http://davehouston.org/switchmode.htm (http://davehouston.org/switchmode.htm) However, my link no longer leads directly to the power supply.
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Not sure if this will be of any assistance.
I have some of the old All Electronics Catalogs on file.
I could not find the DCTX-1280.
Their DCTX part numbers where for unregulated DC supplies. So if your load was below the 800mA the output maybe higher and and above 800mA the output maybe lower.
You maybe able to find a power transformer type but as Dave mentioned . Most are now switchers.
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Jameco lists AC to DC Linear Regulated and AC to DC unregulated 12 volt 1 amp wall warts.
My exact page links didn't work correctly. So here is their main page.
http://www.jameco.com
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This one probably is a linear model - you also need a $0.95 2.1mm adapter (on the right of the page).
http://www.parts-express.com/parts-express-12-vdc-1000ma-ac-adapter--120-050 (http://www.parts-express.com/parts-express-12-vdc-1000ma-ac-adapter--120-050)
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These guys are just down the road:
http://www.vetco.net/catalog/product_info.php?products_id=14098
I'm still looking around, but that seems like a valid candidate.
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Just remember. If the supply is not regulated. It output maybe high with a light load and low with a larger load. Than what the 12 volt 1 Amp rating is.
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I am confused on how the current is determined on power supplies like these. I originally thought that the PSU would convert the 110VAC to the voltage and current specified and that would be forced through the electronics that are plugged in. But at some point I was told that in reality, these PSU's can provide the current at the designed voltage. So, if you have a device that needs 12VDC@0.5A, as long as the wall wart is listed as 12VDC and >0.5A, you would be good. The device will pull what it needs up to the designed current of the PSU. Are these unregulated units different? Or, do I have this completely wrong?
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A power supply rated at 12 volts 1 amp. Can supply up to 1 amp of current, at 12 volts. A device using .5 amps would not exceed the 1 amp rating of the supply you chose.
The power transformer in the wall warts voltage varies with the load.
In a unregulated wall wart. The voltage maybe higher than the rating with a light load. The rated voltage at the specified current and lower if a higher current is being supplied.
The regulated type. Takes the varying voltage and keeps it at the rated output voltage as long as the current rating is not exceeded.
So an unregulated wall wart rated at 12 volts 1 amp. Will be outputting a higher voltage, unloaded or lightly loaded.