DC Extension Cable

[Griffin NoName]

This is my ongoing saga of transferring tapes to digital. I have been making some rapid progress. I now have all the equipment and all the software I need.

One remaining problem.




Smudgy drawing....but..... as you can see the AC adaptor - DC Jack cable (X) is too short to reach from the power socket to the speakers/dock. The power socket (labelled extension socket) cannot be moved as it has other things attached to it which need it to stay where it is. And there's no other power point.

So, I thought perhaps I could get an extension lead to plug the DC jack into and then at the other end of the extension cable to plug into he DC IN point.

See red cable below. This is what I need.



I found https://sslrelay.com/s75376715.oneandoneshop.co.uk/sess/utn;jsessionid=154b8d4bc7af534/shopdata/index.shopscript?main_url=https%3A%2F%2Fsslrelay.com%2Fs75376715.oneandoneshop.co.uk%2Fsess%2Futn%3Bjsessionid%3D154b8d4bc7af534%2Fshopdata%2Fproduct_overview.shopscript

It's <quote>One of a range of low voltage DC extension cables for use with power supplies for products from security cameras to laptop computers.

Is it the right thing?

Next question, if it is, how do I find out if I have 2.1mm or 2.5mm ?  I suppose as they are cheap I buy both sizes.

[Aggie]

Wouldn't it be easier to use a second extension cord?  This may or may not be safe.  DC cable would be safer, presumably, but harder to get.

[Bob in a quantum-state-of-faith]

Okay.

1) Do you have a Radio Shack within driving distance?  Or something equivalent?   Basically, take your wall-wart (power-supply) with you, and try the various connectors in the store, to sort out which is which.

If that is not an option, you *could* make a 1:1 picture of it.   Put a ruler next to your plug-end.  Orient the plug directly at your camera.  Snap as close as you are able, and still focus.

Now, using your ruler, zoom in and out your snap, until the photo-ruler is the same size as the real one.

Now.  You can take a fine-MM ruler and actually measure the end of your plug-- it's easier on the paper image, than on the plug itself.  Edit:  you don't even need to print-- use your screen itself, zoom in and out, the picture until the ruler is the same size as the real one.   Then, measure the image on your monitor with a good mm ruler.

As for 2.5, 2.1?  I'm sorry to point out, that there are also 3.0, 3.5, 3.1, 2.7, 2.0, 1.9.... etc, etc, etc.

But wait, it's worse than that, Jim-- I'm a Doctor, not an engineer:  the center-pin comes in a variety of sizes, TOO.  <gag>  From 0.5mm right up to 3 or 4 mm on the very largest ones (but those are rare in personal electronics).

*sigh*

[Aggie]

Bob, any thoughts on just getting a second regular extension cord to bridge the gap with the existing DC adaptor, safety-wise?  You're more electrically inclined than I am.  Remember that it's 220V or something in that area instead of the N.American standard.

[Bob in a quantum-state-of-faith]

Bob, any thoughts on just getting a second regular extension cord to bridge the gap with the existing DC adaptor, safety-wise?  You're more electrically inclined than I am.  Remember that it's 220V or something in that area instead of the N.American standard.

I had assumed she did not wish to use such an obvious 'fix' for whatever reason(s). 

But, there's nothing inheriently wrong with using a quality extension cord between the wal-wart and the mains power-- wal-warts typically pull milliamps or at worst, an amp--- tiny current for any quality extension cord.

For safety, the cord could be encased inside a PVC water-pipe, if desired, or secured to the wall/baseboard with tape or clips.  I've done this many times-- my favorite method, is to use strips of plastic salvaged from packaging, wrapped around the cord, leaving a "flag".  Then I staple through the flag into the wall/baseboard, taking care to miss the cord.  Works like a charm.   2" (4cm) and 1/2" (1cm) wide on the strip works best-- and thin cardboard, or heavy paper works as well.  But, I'm partial to the clear plastic-- it blends better.

As for casing the cord within the pipe?  That does take some prep work-- you need to slit the pipe with something.  I use my table-saw, but this is not always available.   However, if you can borrow one, set the blade-height to 1/2 the diameter of the pipe.  Set the fence over to 1/2 the diameter also.  You'll have to remove the anti-kickback thingy, as the pipe will be slit in one place only, along it's length.

Now, carefully start the saw, and slowly feed the pipe, holding it firmly against the fence, and down.  Keep fingers away-- when you've cut about 1/2 way down the pipe, stop, move to the outfeed side, and slowly pull it completely through.  A helper is golden, here.

Once the pipe is slitted, you can push extension cords into it, protecting them from being stepped on, etc.  Leave a bit of slack in the length of the pipe, to allow some freedom at either end.

[Aggie]

I was thinking about a cord between the extension socket and the 'wart. So, we'd be looking at:

mains power -> extension socket -> extension cord -> adaptor

Are two extension cords in series an issue?  Obviously, a single long-enough extension cord from the mains to the DC adaptor would be a better idea, but it's been stated that there's no other available power point (hence the need for the extension socket / power bar).

Cords are cords, so the tripping hazard with the extension cord is not likely to be any worse than with the DC extension (the extension cord would likely be more visible, if anything). I somehow suspect a table saw is not going to be an option here _{but I'm still mentally plotting an appropriate jig and push-stick to hold the pipe in place laterally and vertically}.

Griffin, how long of a gap do you need to bridge, in total?

[Griffin NoName]

Sorry Bob, I can't quite follow your measuring instructions !

On the other matter, the siting of the equipment and the current position of the extension (5 gang) socket is a wiring nightmare. There are shelves and books and a cupboard to negotiate, and that's before one reaches the bed (which is solid to the floor and immovable) where the wires have to feed through a gap to get to the 5 gang socket which is inside a kind of drawer that pulls out from the bed. And which I can just about get a hand in to put the plugs in and out and switch the power switch on or off. So no I don't want another extension socket - there's nowhere for it. It's going to be difficult enough to manipulate (and hide as much as I can) a DC extension lead.

1. Can you tell me if the url I posted shows a suitable type of lead?

I need to know.

[Sibling Zono (anon1mat0)]

Using an extra regular extension isn't a problem (not for this particular use anyway). Any reason why you wouldn't use another regular cord extension (in a serial fashion) Griff?

[Bob in a quantum-state-of-faith]

1. Can you tell me if the url I posted shows a suitable type of lead?

I need to know.

Link did not yield anything-- perhaps because I'm not in the UK?

To measure the plug-- you need a reasonable digital camera that can get close enough.  Cell phone is unlikely to be good enough.

Tape plug to edge of table, such that the plug-end is just at the end of the table, with the hole pointing into the room. Taping it's housing is good enough.

Next, take a ruler (metal, wood-- markings need to be clear) and tape it to the edge of the table, just below the plug, so that the flat ruler is just under the plug's hole.

Now.  Standing with the camera looking at the table, move yourself back and forth away, until you are just into focus-- as close as you can get, but still in focus.  A few snaps may need to be taken to be sure.

Next, upload the pic into your PC.  Load it into a picture manager/viewer that has zoom in/out capability.   Physically hold up your ruler to the screen, and adjust the zoom until the picture of the ruler is the **exact same size** as the physical one.

You have just created a 1:1 image of the plug. 

Now, using your ruler's MM scale, carefully measure the diameter of the picture [on the screen] of the plug-end.  It will be close enough. 

Hope that is more clear.

[Griffin NoName]

Yes that is clear. I'll give it a go.

Zono, I thought I'd explained why a serial extension power extension was out of the question in the post above. There's no room for one.

[Sibling DavidH]

Griffin, if you can't get a proper dc extension, it's not too hard to cut the dc wire and splice a length in.  It's best to solder the joints.  Stagger them, like this:

-------------*-------------------*--------------------------------
-------------------*--------------------*-------------------------
so they can't touch.  If you can't get sleeving you'll have to insulate with tape, but ideally fix it from unravelling with a blob from a hot-melt glue gun.  You aren't going to set the house on fire or electrocute yourself with the low voltage and current involved, but a short could destroy the wall wart.

BUT YOU MUST get the polarity right (not swap + and -).  Often the wall wart's cable has a white tracer on one wire.  If not, you need a multimeter.  The inside of the dc socket is usually +, but check first.  Also, there's usually a little diagram next to where you plug it into the docking station.
Don't try this if you are not confident, but it's a safe, cheap and easy fix if you can do it or get someone else to.  A proper extension would be better, of course.
BTW When Bob sats 'Radio Shack', read Tandy in the UK.  Also Maplins are excellent.

[Bluenose]

Griff, if you can take one end of the low voltage cable into an electronics shop and simply tell them you need an extension cord with a female connector at one end and a  male connector at the other, the same size as the one you take in, they should be able to help you.  At worst, they can tell you what size the plug is and then let me know and I'll make you a cable and mail it to you.  Would only take a few days to get to you.

[Bob in a quantum-state-of-faith]

Griffin, if you can't get a proper dc extension, it's not too hard to cut the dc wire and splice a length in.  It's best to solder the joints.  Stagger them, like this:

-------------*-------------------*--------------------------------
-------------------*--------------------*-------------------------
so they can't touch.  If you can't get sleeving you'll have to insulate with tape, but ideally fix it from unravelling with a blob from a hot-melt glue gun.  You aren't going to set the house on fire or electrocute yourself with the low voltage and current involved, but a short could destroy the wall wart.

BUT YOU MUST get the polarity right (not swap + and -).  Often the wall wart's cable has a white tracer on one wire.  If not, you need a multimeter.  The inside of the dc socket is usually +, but check first.  Also, there's usually a little diagram next to where you plug it into the docking station.
Don't try this if you are not confident, but it's a safe, cheap and easy fix if you can do it or get someone else to.  A proper extension would be better, of course.
BTW When Bob sats 'Radio Shack', read Tandy in the UK.  Also Maplins are excellent.

Ha!  I did **exactly** that, on an extended trip to Yellowstone a coupla years ago, with family.  The battery on my brother's kid's portable DVD player died-- normally, you'd charge it via the cigar lighter up front, then the kids in the very back (a land-yact, something called a "suburbian"?  With 3 rows of seats and luggage stowage behind that) could watch movies or "Little Einstein" shows.  Alas, by day 4, the battery would not hold a charge through even one movie.  They had the cigar-lighter charger which would double as a power cord, but it was way-short.

So.  What to do?  We were traveling via the scenic route, so no big-city solutions available.   The fix?  I sacrificed an extension cord I happen to have in my bag-- the ordinary kind, and cut and spliced exactly as you describe, the power cord.  Band-aids served as both insulation and to hold it all together.  Worked like a charm.



McGivver would've appreciated the solution.

[Sibling DavidH]

Some would be horrified, but I've done it to extend my just-too-short lawnmower lead (230V). 

Offset soldered joints, very neat, with lengths of vinyl tubing slid over and fixed with hot-melt glue.  Overall a long offcut of thickish plastic garden hose, the whole filled right up with hot-melt glue.  Highly unofficial but as safe as houses; it's been fine for 3 years.

But you must not forget to slide all the pieces of sleeving on before you solder!

[Bob in a quantum-state-of-faith]

Some would be horrified, but I've done it to extend my just-too-short lawnmower lead (230V). 

Offset soldered joints, very neat, with lengths of vinyl tubing slid over and fixed with hot-melt glue.  Overall a long offcut of thickish plastic garden hose, the whole filled right up with hot-melt glue.  Highly unofficial but as safe as houses; it's been fine for 3 years.

But you must not forget to slide all the pieces of sleeving on before you solder!

Hot glue is fine, but I prefer the flexibility of "sensor-safe" RTV or silicone glue.  The blue formula will not corrode your copper wires (the sensor-safe ensures this), and it remains flexible over extended periods of time.

For sleeving, I prefer heat-shrink-- it's a sort of plastic, that when warmed with a hair drier or hot-air-gun, it shrinks to 1/2 or 1/3 of it's original size.  If you slather silicone inside, before shrinking, you get an excellent, protected and waterproof joint.   Smaller heat-shrink tubes over each line, then a larger tube over the whole, re-creating the appearance of a continuous, one-piece wire.   If you take care when soldering the joints, so as to not let them get too large?  The finished diameter is similar to the insulated part, after shrinking the heat-shrink.   The silicone will ooze out either end, I just wipe that off.

I've repaired many a damaged extension cord exactly this way-- as good as, or better than when new.  And waterproof.