Introduction: Replacement Laptop Cord

Picture of Replacement Laptop Cord

I absentmindedly left the cord for my laptop power supply somewhere the last time I used the computer away from home. I was chatting with friends as I was packing up and forgot it. The business said no one turned it in as a found item.

I could order a new one and it would cost me about $20 (US) by the time it is delivered. I decided to make my own from this appliance replacement cord I found at Home Depot for $6.33 (US).

Step 1: What Size Are the Power Supply Pins?

Picture of What Size Are the Power Supply Pins?

Drill bits make handy sizing samples. By sight guess which drill bit is closest to each pin. All three pins were a different size on my power supply: 3/32, 764, and 1/8 inch.

Step 2: Test Your Guess

Picture of Test Your Guess

It is not easy to get an exact size on the pins by sight. Test to see if your are correct.

Strip some #20 solid copper wire and wrap a loop around the shank of your drill bit. Slide the loop onto the pin. It should not be too loose or too tight. Try a different drill bit if the loop does not fit the pin properly.

Step 3: Wrap a Coil

Picture of Wrap a Coil

Using the drill bit as a form, wrap a coil a 1/8 inch longer than the pin in the power supply.

Step 4: Compress for a Tight, Closely Wound Coil

Picture of Compress for a Tight, Closely Wound Coil

Press down on the coil to push the windings close to one another.

When finished with a coil, cut the coil from the wire and set it aside. Size and wrap a coil for each remaining pin.

Step 5: Solder

Picture of Solder

Slip the coils onto their respective pins. Insert the correct ends of the appliance repair cord into the ends of the coils and solder each.

When finished, push hot glue into the opening as much as possible to make a plug fitting.

Step 6: The Plug Fitting

Picture of The Plug Fitting

This is the plug fitting I got after the hot glue hardened. Actually, the hot glue did not flow into the bottom of the opening on the power supply as well as I had hoped. I have built it up some manually and trimmed it with a sharp knife to fit the opening. If I had not run out of hot glue sticks, I would have built it up more to cover the bare copper and make it safe from electrical shock. I plan to do that yet.

Step 7: Finished

Picture of Finished

The green power light from my laptop is glowing. I think I will not disconnect the cord from the power supply in the future so that I am less likely to forget the cord. But, my cord works. It cost me about $6 instead of about $20, and I did not need to wait 10 days to 2 weeks for delivery.


robothead (author)2015-01-14

nice work make a kit out of it and give it everyone

muyguapo (author)2011-01-12

Why not use Sugru instead of hot glue to form the connection?

Phil B (author)muyguapo2011-01-12

I have never used Sugru, had never heard of it until Instructables had a contest for things made with it, and do not know where I would buy any other than on-line. From what I have seen of it in projects by others, it would probably work.

muyguapo (author)Phil B2011-01-12

Online is the only place I know to buy it.

fourletterfame (author)2009-07-27

The patent websites I looked at for glue sticks indicated a low end melting temperature of 194F and a high end of 248F (90C and 120C respectively). If your power supply is in the heat range of boiling macaroni, you have deeper technical problems.

Phil B (author)fourletterfame2009-07-27

I have been using this laptop cord exclusively during the last four months and it does work just fine. You make a good point about the cooking temperature for macaroni. I expect carpet fibers and table top finishes would be seriously damaged, too. Thanks.

Bjorno (author)2009-04-06

A good idea, but it is a risky endeavor for a small savings. Most retail electronics shops sell the "Mickey Mouse" style cables for ~%5.

Phil B (author)Bjorno2009-04-06

I do not enjoy electrical shocks any more than anyone else and take great pains to avoid them. If I thought it were not completely safe, I would not have made it, nor would I use it. My last experience with purchasing a cable like this was in 2006. The only place I could find was on-line with Radio Shack. The cable was $12.95 plus shipping.

Bjorno (author)Phil B2009-04-07

Neither do I. The only part I worry about is the fact that you used hot glue to assemble the plug. Adapters like that can generate a decent amount of heat, enough to soften the glue and potentially short out. Though it is a slim chance, considering the prongs will hole the wires in place, it is still a worry of mine. Plastic epoxy is generally what I use to fashion that type of thing. Heat does not affect it and it is quite solid. I was a little off on the price, it is still around that $12 mark at most places.

Phil B (author)Bjorno2009-04-07

As I explained to one of the people who left a comment, my power supply does not get more than lukewarm. It is never so warm that I cannot hold it comfortably, even when charging a depleted battery. That is not hot enough to melt the glue. I also mentioned in one of my responses that I did an Instructable on an Auto Charger for 6 or 12 Volt Systems. In it I used hot glue to insulate the transformer primaries. In 20 years of use I never saw any breakdown of the hot glue insulation. In a worst case scenario, let us say the hot glue softens considerably. The copper coils are still held apart from one another by the pins on which each sits. Even if the hot glue around the coils became gooey, the hot glue away from the pins would not get hot enough to become soft. I really think it is going to hold up quite well. I suppose a good epoxy would have been the stuff they use for sealing an automobile gasoline tank.

Bjorno (author)Phil B2009-04-20

Your power supply does not get more than lukewarm.

But you are posting this as an instructable for other people who's power supplies might very well get hot.

Keep in mind that I am not trying to knock you down, or insult your idea; only to add to the design.

Two heads are better than one.

Phil B (author)Bjorno2009-04-21

If someone is concerned about hot glue melting on his power supply, he should plug it in and rest a stick of hot glue on the hottest part. Come back in an hour or two and see if the glue has melted.

Bjorno (author)Phil B2009-04-21

But how are they going to do that if they are trying to use your instructable to build a cable in the first place?

Phil B (author)Bjorno2009-04-21

Some options would be: 1) Borrow a cord from a friend with the same style power supply. 2) Lightly solder leads from an improvised cord to the ends of the pins and tape them reasonably well for the duration of the test. (Include as small a fuse as possible in the circuit for extra protection.) 3) Follow steps 1 through 5 of this Instructable for a test, taping as needed to insure nothing can short during a test. (See the note about a fuse in the option above.) 4) Find someone with a laptop whose power supply becomes quite warm after an hour or two of use, even if a different style than yours. Gain his agreement to allow you to conduct your melting glue stick test. I am certain a power supply hot enough to melt hot glue will also damage the finish on a counter, burn skin on contact, melt carpet, and cause spontaneous flames on newspaper. The point is that no normally functioning laptop power supply gets hot enough to make the hot glue I used in my Instructable cause any danger through melting.

Bjorno (author)Bjorno2009-04-06

Er, ~ $5, I should say.

Captmeach7 (author)2009-04-15

I bought one of these at the local radioshack for 9.99, But this is essentially the same thing. copper wire wrapped in plastic. I dont know the difference between the heat the regular coating and the hot glue can take, but so long as it doesnt melt should be fine.

Phil B (author)Captmeach72009-04-16

Thanks. I have checked the plug end I made while using it over spans of a couple of hours. Nothing rises to even the heat of my hand. It seems to be working out just fine.

zzzdude (author)2009-04-11

Now tell me how to fix the other part of the cable, assuming the power supply box is in tact. I really don't want to pay 80 dollars for a replacement...

Phil B (author)zzzdude2009-04-11

I assume you are talking about a flaw in the cable between the "brick" (power supply module) and the plug that fits into the side or back of the computer. It is essentially like replacing or fixing the jack on a pair of headphones or earphones. I believe there are some Instructables on that. The wires often become frayed inside the cable an inch or two back from the plug. I pare away the rubberized plastic covering the power plug. I cut a couple of inches off of the cable on the plug end and strip the wires from the brick back about 1/2 to 3/4 inch. I desolder the the old connections to the power plug and make new solder connections from the stripped cable. Doing them one at a time helps make certain the right wire goes to the right solder joint. Then I coat the plug in hot glue. While the hot glue is cooling, I keep turning the power plug over so the glue does not sag in one direction. I hope this is what you are asking. There is always the possibility the break in your wires is at the brick rather than the plug. That would be more difficult to fix.

zzzdude (author)Phil B2009-04-13

Why thank you. You said exactly what I wanted to hear.

lemonie (author)2009-04-06

Eeew - looks nasty, but I do like it. L

Phil B (author)lemonie2009-04-06

I could have made it prettier, but was running out of hot glue. So far it seems to work very well. Thanks for the comment.

PATSY001 (author)Phil B2009-04-06

You could have also used heat-shrink tubing to insulate the copper before adding the hot melt glue, it would add extra protection against electrical shock. I use heat-shrink tubing for everything.

fwjs28 (author)PATSY0012009-04-06

that would make it more aesthetic...other whys its nice

Phil B (author)fwjs282009-04-06

I have always enjoyed home made things that look crude, but function oh so well. It is fun watching the expressions on the faces of others.

fwjs28 (author)Phil B2009-04-07

haha...i could see taking this into a cafe along with this and watching peoples reaction :P

Phil B (author)fwjs282009-04-08

I just checked the link to the frayed cord thumb drive. Another great thing would be to attach a bent coat hanger with aluminum foil to the laptop screen and tell people it is a WiFi antenna.

fwjs28 (author)Phil B2009-04-08

ha, that would be funny....

Phil B (author)PATSY0012009-04-06

Thanks for a good idea. I have seen the way others use heat shrink tubing, but have never possessed any, myself. It is not a part of my experience and I did not think of it.

hiheenah (author)2009-04-07

Go to a hotel and tell them you stayed there a couple weeks ago and you forgot your laptop power supply in the room. Tell them you can't remember which room you stayed in. They will most likely bring a tub of left behind power supplies out for you to peruse. cost: Free. I work at a hotel. We have at least 50 of these things laying around.

Phil B (author)hiheenah2009-04-08

You raise an interesting concept. I would have difficulty saying I stayed at the hotel when I did not. I would find it easier to say, "I understand people often leave power supplies for their laptops and no one claims them. I can understand these become a burden to you. May I sort through those you have gathered and take one, if I can find one that would work on my computer?"

hiheenah (author)Phil B2009-04-08

even better. If I was at the front desk, I would let you rummage.

ranm (author)2009-04-08

Never forget that your insurance company probably will not pay for any damages caused by any eventual fire caused by this cord. Im not saying that the hot glue won't melt, but you can never be sure. Think about it. Even the real deal electronics you have might break down, even though they are following safety regulations! But in an emergency situation, this solutions seems to be pretty good (Y)

Phil B (author)ranm2009-04-08

What eventual fire? This cord is not going to cause any fire. I have used it a few days now. Nothing even gets warm, let alone hot--not the power supply, not the cord I fashioned, nothing. See my Instructable on an Auto Battery Charger for 6 and 12 Volt Systems. I used hot glue to insulate the primary transformer terminals. The hot glue on it has performed well with no safety problems or failures for over 20 years.

cameron20020 (author)2009-04-08

give the guy a break people! he has some good ideas

Phil B (author)cameron200202009-04-08

Thanks. Thanks. Thanks. Thanks. And, thanks again.

JustDepends (author)2009-04-07

lol i thought this was the entire ac adapter and stuff to.

JustDepends (author)JustDepends2009-04-07

that would have been helpful

Phil B (author)JustDepends2009-04-07

You are very much correct. I believe there are registered users on Instructables who could show us how to build one of those. Sadly, I am not quite the one. Thanks for the comments, though.

rimar2000 (author)2009-04-07

Very good work, Phil. I did something similar, with the exception of the ground cable, for my notebook (my plugs were made of bronze sheet instead of copper cable). Not for lack of the original cord, but because this is so thick that it was not fit in the portfolio. But shortly after, I discovered that replacement cords are sold very cheap with the same plug. Maybe if you had asked or searched at Home Depot, you would have saved the job (and could not have done this Instruction)

Phil B (author)rimar20002009-04-07

Thanks, Rimar. I mentioned in some responses to comments that I needed one of these cords in 2006 and found very a limited number of providers at higher prices. I had not checked since, so, if they are available more places at a lower cost, that is news to me.

bfarm (author)2009-04-07

A few dollars for a real - safe - UL Listed - replaceable line cord would be money well spent. Hot melt glue is not a legal insulator, does it breakdown after a while? Where is the strain relief? Also, the wrapped coils will loosen up after a while and start arcing which should assist in re-melting the glue. Really bad idea.

Phil B (author)bfarm2009-04-07

Thank you for your concern. You might check my Instructable on an Auto Battery Charger for 6 and 12 Volt Systems. I soldered an old line cord from an electric clock to the 120 volt primary terminals of the transformer. After the rubber on the cord was more than 30 years old it showed signs of becoming brittle. I replaced it a couple of years ago with a line cord from a discarded TV. The primary terminals have always been covered with hot glue for insulation. After twenty years of use, the hot glue was still very much intact, showed no signs of breaking down, and has always provided a very good dielectric. Because I swapped cords for a newer one, it now has hot glue insulation only a year or two old. What I did has as much effective strain relief as the original. The replacement cord I bought is much tougher than the original and much more resistant to bending and flexing. My only experience with electrical components arcing involved a UL approved circuit breaker panel. There was arcing between a breaker and a buss bar that ate away most of the buss bar. There was no fire, only no heat from our heat pump one very cold night. I am thinking of leaving the cord I adapted plugged into the power supply, which reduces physical wear that might cause looseness and arcing. I think it would be quite a long time before I see evidence of that. The laptop is already five years old and will likely be retired before any problems develop. But, I will watch for evidence of the things you mention.

Phil B (author)Phil B2009-04-07

I should also mention the laptop power supply is plugged in only when I am using the laptop, which is for only an hour or two at a time, at most.

ins1jlm (author)2009-04-06

you can find the cord you need at goodwill for 2 or 3 bucks

Phil B (author)ins1jlm2009-04-07

I wish I had known that in 2006 when I needed to replace one of these cords. I go to Goodwill once every ten years, whether I need it or not. It is just not a place that comes into my mind.

robotguy4 (author)2009-04-07

Couldn't you also use a pair of calipers to get rid of the guess work? Nice idea with the drill bits though.

Phil B (author)robotguy42009-04-07

Perhaps, but I do not have anything that will reach into the narrow space around the pins. Thanks for your comment. Drill bits are very useful for checking the size of many things, especially the shank end. They often function very well as a "go - no go" feeler gage.

robotguy4 (author)2009-04-07

Very nice Instructable. I wish I had this before I dissembled an old, cheap rechargeable Rockwell drill from the '70s that I bought for $3 at a rummage sale (sans cord). All I had to do was plug it into the wall socket (the drill used wall voltage) and I would (possibly) be good to go.

Phil B (author)robotguy42009-04-07

I think we have all been a day late and a dollar short. As I mentioned in response to Cameron20020, part of the reason for this Instructable was to demonstrate a process for making a special cord for any number of applications. I also considered cutting the case of the power supply open and soldering permanently and directly to connections inside it, but decided against that course. Something like that may have been possible on your drill. Thanks for your comment.

About This Instructable




Bio: I miss the days when magazines like Popular Mechanics had all sorts of DIY projects for making and repairing just about everything. I am enjoying ... More »
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