power/barrel connectors

is a good reference for these buggers. This seems to be one of those areas where standards were so good, they decided to have several of them!

Center-positive seems like a sensible choice although, as you note, not all are set up that way. Fortunately it has become more common for devices to have the little --(.-+ polarity marking, or its inverse.

--
Rich Webb     Norfolk, VA

You don't open them to see what's inside, behind the power connector?

Sounds good.

Can't think of easier, apart from opening up the toys as part of the investigation.

Worst I've seen is a DC powered device after somebody plugged in an AC plugpack connector --> Boom! went the DC filter cap, about the same time as the PCB fuse blew, messy...

Grant.

--
http://bugs.id.au/

I have one handheld radio (Kenwood TH-315A) which uses a NiCd battery pack (8.4-volt nominal). The drop-in desktop charger has a center-positive coaxial jack for a 12-volt supply. The radio has a "DC in" jack which takes the very same plug, so you can run it directly from the wall wart.

The detachable NiCd battery pack has a direct charging input, so you can top it up without needing the drop-in charger... but this input is a center-negative (!) jack of a slightly smaller OD.

I'd have enjoyed the opportunity to be a fly-on-the-wall (possibly armed with a machine gun) during the engineering meetings which selected this design. Why, oh why?

--
Dave Platt                                    AE6EO
Friends of Jade Warrior home page:  http://www.radagast.org/jade-warrior
  I do _not_ wish to receive unsolicited commercial email, and I will
     boycott any company which has the gall to send me such ads!

Exactly. "Standards are great! EVERYONE should have one!" :<

Then there are the "inside out" varieties (Sony is fond of these but Dell and Toshiba also use them on laptops and LCD monitors)

Yeah, but the morons who thought up the marking scheme also didn't think it through very well. E.g., '+' and '-' are usually represented in circles. The connector body is abstracted as "-(o-".

Now, reduce this to the point where you would typically

*greek* text and the connector legend starts to look like "-(o)-" (i.e., ink bleed closes the 3/4 circle that is intended to *almost* surround the center pin's representation.

When I REmark these connectors (and wall warts), I use a circled '-' or a circled '+'. Takes less space than their silly graphic *and* its unambiguous -- even when scaled!

Unfortunately, the connectors that you can usually buy often have shorter barrel lengths than the connectors that are "required" for the device(s) in question. :< Otherwise, I would just buy one of each and build a custom "octopus cable" out of them (which would allow me to label each "tentacle" with a description of the connector at its tip!).

[I use a bag of "tips" -- like shown in the Wiki page you referenced -- that I connect to a mating "receptacle" attached to the programmable power supply. These tips are almost always "longer" than the "standard" ones you can purchase!]

Shirley you jest? :> Too many of these things are snap-together construction (if not outright solvent weld!). Those few that are screwed together hide the hardware under labels, rubber feet, etc. (so accessing them often does cosmetic damage to the device).

If the device is missing voltage/polarity markings and I can't find it online, I *might* consider surgery -- but the device would have to be worth the effort (else just toss it in the recycle bin)

I think having a selection of each of the mating-mating connectors (i.e., the connector that exists on the device) mounted on a labeled piece of phenolic could be a win. Find a tip that fits the device. Then, see which *labeled* connector on the "template" similarly fits this mate.

Yeah, it would be nice if things were all AC. But, I guess they'd rather put the rectifier and regulator in the wall wart instead of the "device". :-/

In article , D Yuniskis wrote in part:

My experience is that there is no reliable hard-and-fast rule, but that *almost* everything has center positive, shell negative. With one major exception that I know of: 9V "stomp box" style musical instrument effect devices tend to be center negative, shell positive. Some other wallwart-powered musical instument devices may follow that alternative convention.

--
 - Don Klipstein (don@misty.com)

What I like to do is "go for it" - take a guess at polarity, usually center-positive unless the device is of a class and voltage that I know to usually be center-negative.

If it works - *woohoo!*

If not, reverse polarity and see if I blew it out. If it does not work at that point, I usually return it to where I got it (usually a dumpster).

Not that I do a lot of this - when I find time to do electronics after my non-electronic day job, I mostly nowadays do stuff that I can get paid for doing. Healthcare coverage inflation and the modern economy is forcing me to work more and play less. My dumpster diving for electronic-related devices in recent years is mainly for power supplies and hardly for prospective loads for them or for devices likely to go into "The Recycle Bin" or products likely to be favored to be sources of components likely useful only in "pure science" "mad-scientist" / curiosity area. I filled my home enough with enough of that sort of stuff already...

--
 - Don Klipstein (don@misty.com)

Huh? Ah, OK. The "desktop charger" is a little "base/cradle" into which the radio can be placed for charging and *that* gets its power from a wall wart. The wall wart can also be plugged directly into the radio (eliminating the bulk of the desktop charger but sacrificing some convenience -- i.e., you can't just "drop it in")?

Ouch! So, there are *three* "equivalent" power connections to the radio:

- set of "drop in contacts" for the desktop charger

- barrel connector to power radio (also charges battery?)

- different barrel connector on battery pack

Are the needs of the battery pack different from those of the radio? I.e., I've seen radios that expected a current limited supply to be connected to the "battery input" connector to top off the battery -- but a low impedance supply to connect to the *radio* (to power the radio).

Of course, picking the same connector for both is daft. (and picking opposite polarities even moreso -- unless they waste a diode drop in each connector)

I try to maximize my chances of getting it right the first time. Current limiting the supply usually gives me a second chance if the polarity is unmarked and I get it backwards (Sony seems to be the biggest culprit, there).

Yup, been there, done that. We've been on a "purge" for a number of years, now.

I probably rescue 6 laptops a year, dozens of LCD monitors, etc. Diverting these from landfills (*or* The Recycle Bin) and getting them back into "circulation" is a small effort on my part -- yet usually pays big returns when you see someone who couldn't normally afford such things smile at the "gift". Or, even folks who *could* afford such toys (it does no one any good in a landfill; and I suspect the recycled value has got to be a few percent of it's "working value")

Heck if I know. What I've started doing, is lopping the last ten inches of cable off a wall-wart supply, and reconnecting it with a four-position (Molex Minifit latching nylon) connector. Pin 1 is low-voltage (+) , anything from 0 to 6V; pin 2 is low-v (-); pin 3 is high-voltage (-) and pin 4 is high-voltage (+). Usually it's only using two pins, but +5/+12 power for external disk drives uses all four (#2 and #3 both are grounds). For AC, connections are at pins 2 and 3 (so the DC targets would not connect, or just short it rather than get blown up). So, all my tips are pluggable into all my wall-warts, and if the wall- wart has the right rating, and the tip is the right connectivity for the target, that wall-wart can power that target.

And every time I want another unit pressed into service, I either find a correct wallwart, or connectorize an orphan wallwart appropriately. The work is never completely done, of course. Little cardboard string-tags on the tips is the next to-do item.

Ah, OK. You're expecting to deal with more than just two-conductor barrel connectors. (I think this is a more "expansive" approach than I've been pursuing)

Great! You've obviously thought this through!

I don't see any easy way to label things. What is particularly annoying is that many tips

*appear* to be color coded. But, there doesn't seem to be a "standard" that applies, here. :(

I have dozens of assorted "tips" like the first photo in:

I have a digitally programmable power supply (i.e., a keypad and display on the front panel) with the mating connector wired to its output connection. So, I can power a device by finding the connector that "fits", then programming the PS for the appropriate voltage (I can't do AC wall wart emulation)

Unfortunately, it feels a lot like "having a can full of random screws" that you dig through in search of the

*right* screw... :<

Did you come across this entry? -->

It seems like there are color standards... just lots of them -- EIA has one, Radio Shack has one, etc. So it if effectively useless... (yellow and black do seem the most common, for whatever reason).

---Joel

Yes.

Exactly. The problem with standards is when folks don't

*follow* them. E.g., I came across a set of socket drivers that seemed to think the role of colors was to make the driver set more "attractive" :<