How to find a receptacle for a wall wart's plug?

[jkiker]

Hi all,

Regarding my current project and the lighting, I have done the background research including questions on other threads in this sub-forum. I have bought a selection of LED's and resistors, obtained tools, wiring, a battery holder, a wall wart, and a switch for having both battery and wall power. Thanks to everyone who has hung in and answered my noob questions along the way.

I think this brings me to a last question. I think I would like to have the wall wart retain the ability to be unpugged from the base, rather than simply cutting off the device end of the plug and wiring it up directly to the power switch. This would allow me to use the power supply for other projects. I went to a local Radio Shack and a couple of other places and was told that the only plugs they carry are adaptors for one size plug to another. I have visited Digi-key and Jameco this morning as well; the problem is, I cannot figure out the correct terminology which will allow efficient searching for this device.

So what is this thing called, which can be wired into the model/base power system and that has a receptacle to accept the wall wart's cylindrical plug?

TIA, Jim

P.S. I do realize I am making this more complicated than is usually the case; on the other hand, I can foresee cases where I might have only battery or only wall power available for the model and I want to be able to go either way if needed.

[Paulbo]

Your local Radio Shack will have the part you need, ready to be mounted onto your base. While you're there, pick up the matching plug so you can add it to your battery pack and then you swap power supplies in under 5 seconds.

[Tchail]

It sounds like you're looking for a DC Power Plug & DC Power Jack.

I tend to use Size K-Coaxial connectors.

Here are the Radio Shack Part numbers:

Plug: 274-1567

Jack: 274-1565

Best of luck!

-Tchail

[jkiker]

Gentlemen,

Thank for your quick replies. I stopped by the closest Radio Shack where they told me they didn't have anything like that. But I didn't take No for the answer and went looking in their bins. I found a panel mount coaxial power jack, size M, which fits my wall wart. Success!

To follow up, the unit has three wiring pins; looking at the back, the center pin terminal is at eight o'clock, the "shell" terminal is at 12 o'clock, and the switch contact terminal is at 4 o'clock. How do I attach it to my two power leads? I am such a noob... :-)

Thanks, Jim

[Paulbo]

There should be a wiring diagram on the back of the package. You want to make sure that you match + to + and - to - as shown on the little "circle with a dot and line" diagram that should be on your power supply. (The dot corresponds to the inside and the circle/C corresponds to the outside.)

[jkiker]

Paulbo,

Well, that is just the issue. The "diagram" on the back of the package is a drawing of the back of the jack, with the three terminals labeled as i wrote above. It is a "what," not a "how." I think the 'center pin' equates to + , but that leaves two choices for the - , and I'm still a bit confused.

TIA, Jim

[Tchail]

I think Paul is referring to something like this:

http://upload.wikimedia.org/wikipedia/c ... larity.png

This indicates whether the "pin" or the "sleeve" of the output coming from your AC adapter is positive or negative.

Is there any chance you could post a picture of the unit you're talking about?

Also, do you have a digital multimeter?

I've found that in figuring out how to wire these kinds of plugs, that a AA battery holder and a digital multimeter are generally the easiest way to determine how to wire a connector to get the correct polarity.

[Paulbo]

I think Paul is referring to something like this:

http://upload.wikimedia.org/wikipedia/c ... larity.png

This indicates whether the "pin" or the "sleeve" of the output coming from your AC adapter is positive or negative.

Is there any chance you could post a picture of the unit you're talking about?

Also, do you have a digital multimeter?

I've found that in figuring out how to wire these kinds of plugs, that a AA battery holder and a digital multimeter are generally the easiest way to determine how to wire a connector to get the correct polarity.

Yup, Tom, that's it. Google didn't turn up an image like that and I was too lazy to take a photo of the front of a wall wart and uploade it.

Totally concur that a digital multimeter is a must-have. Radio Shack used to have a great little one (about 1 x 2 x 4 inches) that was super accurate (checked it againt my calibrated resistors, and voltage and amperage sources and it was dead on) AND it was cheap ($20). I just checked their site and they don't carry it anymore

(Not to self: take much better care of my multimeter than I have been recently.)

[jkiker]

Tchail and Paul,

Are we perhaps speaking past one another here? I looked at your link and I understand it perfectly- one terminal is + and the other is -; no problems. I do not have such a diagram on this jack's package- only the drawing of the jack from the back, showing the three terminals. The three terminals are labeled Center Pin (8 o'clock on the drawing) Shell (at 12 o'clock), and "Normally closed switch contact" (4 o'clock). There is a line drawn connecting the Shell and switch contact terminals.

So, could I use the Center Pin as my positive contact, the Shell terminal as my negative, and leave the on-off Switch Contact alone and have a workable circuit?

And while I understand your point about a multimeter, I do not have one and I'd prefer to get through this one project without any more tools if I can. Time will tell on that point...


Thanks, Jim