Wall wart plugs

There ain't no such thing .. I've seen up to 6 pin connectors used for 5 voltage wall warts and I doubt if that's even the record.

Norm

It is certainly a place for a standard but these electronic guys don't want anything you got from somebody else to be useful on their product.

Actually there are good reasons for keeping someone else's wall wart out of my input plug unless there's a very good match between polarity, voltage and current supply. I certainly wouldn't want a center negative, 18 V AC adapter plugged into my label printer that expects 5V DC with center positive.

There certainly aren't a sufficient variety of connectors for all of the different polarity, voltage, current combinations available so we'll probably never see a standard emerge despite a real need for it. To see the variety of available combinations, look at one supplier's list of 143 DC output wall warts at

Unfortunately there are no standards at all so it's a hit-or-miss proposition as to whether a foreign adapter will mate with a piece of equipment. Usually as soon as I get one, I create a label that indicates what equipment it goes to.

Norm

That still is not adressing the issue of why there isn't a standard. It is only engineering lazieness and an intentional attempt at propriety that makes that

18vac plug fit in your 5vdc device. If NEMA came out with a half dozen (or less) standard plug/voltage combinations I can't imagine what you would need more for. If you did you could come up with a "non standard" plug for it. Most of these end up going into a regulator in the device anyway. I have SIX wall warts plugged into the PC I am using right now. That is ridiculous! There must be at least 2 dozen around the house, plugged in and using current all the time. If you could consolidate these into a few "switcher" supplies with multiple cords they would save lots of electricity nationally.

|>Actually there are good reasons for keeping someone else's wall wart out of |>my input plug unless there's a very good match between polarity, voltage and |>current supply | | That still is not adressing the issue of why there isn't a standard. It is only | engineering lazieness and an intentional attempt at propriety that makes that | 18vac plug fit in your 5vdc device. | If NEMA came out with a half dozen (or less) standard plug/voltage combinations | I can't imagine what you would need more for. If you did you could come up with | a "non standard" plug for it. | Most of these end up going into a regulator in the device anyway. | I have SIX wall warts plugged into the PC I am using right now. That is | ridiculous! | There must be at least 2 dozen around the house, plugged in and using current | all the time. | If you could consolidate these into a few "switcher" supplies with multiple | cords they would save lots of electricity nationally.

Too bad that organizations like NEMA won't let people like you and me submit proposals for just such things for this purpose. So, do you think we should approach the EPA instead to do this?

Maybe this is something the EU can do. Those folks see more likely to come up with a standard than we will. If a producer needs a standard plug to get a CE stamp it will become a world standard pretty fast. The line side will always be "country sensitive" anyway but I see no reason why the machine side shouldn't be standardized. How many voltages do they need? If the world would just tell engineers "you get 3, 6, 9, 12, 18 and 24. Work with that" we could build damn near anything.

|>Too bad that organizations like NEMA won't let people like you and me submit |>proposals for just such things for this purpose | | Maybe this is something the EU can do. Those folks see more likely to come up | with a standard than we will. If a producer needs a standard plug to get a CE | stamp it will become a world standard pretty fast. The line side will always be | "country sensitive" anyway but I see no reason why the machine side shouldn't | be standardized. How many voltages do they need? If the world would just tell | engineers "you get 3, 6, 9, 12, 18 and 24. Work with that" we could build damn | near anything.

I'd add one more voltage to the mix: 36

The reason is that US automobiles are switching to that over the next several years and that can mean a number of consumer DC powered devices that use 36 volts. This connector should be a fairly beefy one and include a built in fuse.

Different families of semiconductor technology have different voltage requirements (3 V., 5 V. 12 V.) It is unlikely that a standard would be developed strictly to standardize a plug in transformer.

Also, It's not just the voltage that varies. the current or more specifically maximum current is also variable (25 ma, 50 ma, 100 am,

500 ma, 750 ma, 1 amp, 3 amp, 5 amp) There are many variations.

Plus, many devices run on AC so the wall wart is just a step down transformer.

If you just are concerned about voltage, Radio Shack makes a switchable (universal) DC power supply that has most of the voltages you indicated. It will do polarity reversals also.

Beachcomber

Virtually all of these things have onboard regulators that feed the electronics. That is certainly true of the ones that use AC. In fact most "AC" stuff will run just fine on DC since the first thing they do is rectify it. The wall wart is such dirty power not much will run straight off it. BTDT . Hang a scope on most of them and you will see they are barely filtered at all. The "X volts" is just a rough approximation and can be +/- 20% or more.

| Also, It's not just the voltage that varies. the current or more | specifically maximum current is also variable (25 ma, 50 ma, 100 am, | 500 ma, 750 ma, 1 amp, 3 amp, 5 amp) There are many variations.

If you had a blade system, longer blades can represent more available current, while space between blades can represent voltage. But you better not get them spaced so far that someone gets 120 volts on it.

I've ordered many different wall-wart DC power supplies for various industrial prototype projects so I have a bit of experience in this area.

In addition to the AC-DC, voltage, current, and polarity variations, wall warts come in two flavors.... Regulated and Un-regulated. It's really the designer's choice. In some cases... it's better, cheaper, more reliable, whatever to put the regulator in the device being powered. In other cases, its better that the wall wart supply the regulated power to the device.

Standards are a good thing, I would agree. But I think that history shows that there are many entities (governments, manufacturers concerned about proprietary products, etc.) that are opposed to a world standard when it comes to technical equipment. Or perhaps they are more interested in promoting their version of what the world standard should be. Otherwise we would have one world standard for electric power delivery, telephone jacks, tv systems, DVD's, etc. and this is not the case.

Beachcomber

I am not sure the current really means anything. The equipment should have it's own current limiting device internally. The reality is you can solder in the fuse because if it starts drawing excessive current it is probably because it is broke anyway.

The current rating refers to the full-load capacity of the wall wart power supply. Some devices will draw 25 ma and some will need 500 ma or more. Connecting an unregulated high current supply to a device that does not have a regulator, and is specified to operate on a lower current capacity power supply can, in some cases, cause damage to the device.

Digital Cameras in particular sometimes have strange voltage/current requirements.

Again, this is simply poor engineering. If the device has critical voltage requirements it WILL have internal regulation. The reality is most CMOS will run with anything from around 3v to around 15. The power should be fairly clean and that is why most things do have onboard regulation. The wall wart may give them noisy, unfiltered DC in the 5-8v range, nominally called 6vdc but the onboard regulation will make it fairly clean 5v or so. I have several big boxes of wall warts collected over many years in the computer business. What is imbossed in the case is just a rough guess about what comes out the wire. These are NOT precision power supplies. It is not an unreasonable requirement that electronics be designed to run off of a few selected voltages that have a standard plug. Most are designed for a nominal input voltage range anyway and the wall wart selection is an afterthought, driven by the bean counters. You get what they could buy a ship load of, as cheaply as possible. As soon as some environmental group decides that billions of wall warts, cooking on the wall, are destroying the planet, we will see the manufacturers jump on the "standardize/economize" bandwagon.

If you don't think that current means anything, I have a few 150 ma wall warts you can run your computers on -- just give me the power supplies that came with them.

I agree the supply has to be sufficient for the load but the implication a few notes ago was you could have a supply that had too many amps or words to that effect. My thinking is you could have one supply with a few outputs that would run all of the wall wart loads on a typical PC. I have 6 warts now..

It's because manufacturers are cheap = lazy. If you use a wall wart, you don't have to jump thru hoops to get UL certification. As long as the voltage going into the box is sufficiently low, it's almost automatic.

Norm