I know it’s the old round pin we used for phones back in the day but can someone send me a link to the exact one because I’m seeing too many round pin charges of different sizes. Also where do I go for tech help related questions like these? Is this the right community?
So that’s a DC power connector, but we’re going to need more info before we can give you specifics.
For starters, we need to know the polarity. Basically, the pin is going to be one side of the charge, and the sleeve around the circumference is going to be the other. Look for something 
to see what the polarity needs to be. The center dot is the pin, and the C shape is the outer contact.
Next, we need to know the voltage and amperage. This should be listed somewhere on the device. Most barrel connectors are 12v, but you occasionally see 5v (when they’re powered via USB) or 20v. So that 12v isn’t a 100% guaranteed thing and it’s worth double checking. For amps, you simply need something above whatever the device is listed at. Amperage is basically how much power the device actually uses, and bigger devices will draw more power (and need a bigger power supply.) If it shows that it draws 1A at 12v, then a 12v 1.5A power supply will work, but a 12v 500mA (that’s 0.5A, since each milliamp is 1/1000 of an amp) power supply will overheat.
Lastly, we’ll need to know the diameter of the barrel. These connectors are standardized sizes, but there are a lot of different sizes. 
. So you’ll need some way to measure the connector and see how big it is. Easier said than done.
If you’re able to figure out the first two parts, (polarity and voltage/amps) you can get a universal power supply (with the appropriate voltage and polarity, and rated for something at/above the device’s listed amperage) that comes with a variety of barrels. Then you can simply find the right size barrel via trial and error.
Looks like a barrel plug. These are very common and finding s as replacement should be easy. On the underside of the lamp there will be writing that says what the electricity requirements are. e.g. 12V—-400mA Look up a replacement using those numbers.
It doesn’t say anything on the lamp but I think I can find that on the amazon listing. Thanks
If you know the lamp model number or manufacturer or anything like that you could possibly find the specs online somewhere. I think they also sell some "universal" type barrel plug power supplies that come with various sized barrel connectors.
Ah yes, you must mean the biblically accurate universal barrel plug adapter.
Edit: I had something like this guy growing up and used to use it to make sparks and other shenanigans.
Edit: I had something like this guy growing up and used to use it to make sparks and other shenanigans.
What utter goofball was it who ever built a device with reversed polarity?
Some Chinese devices come with reverse polarity.
Your best bet is to find a universal charger. They sell chargers with like 20 barrel tip sizes.
One thing to remember is that the Voltage needs to be exact, but the supplied Amperage can be equal or higher then the original power supply.
So if you are trying to replace an originally 12v 400mA power supply you can also go with a 12v 500mA or 1A (1000mA) power supply. But 12V 200mA probably won't work and for example 19V 400mA might outright destroy your device.
It's a DC connector pin; but that's not as important as knowing the proper voltage and diameter which I couldn't say from this image and the info given.
Usually, the voltage info is written somewhere near the port, but this isn't always the case.
That’s great. I’ll try using that on the search bar.
Also be careful with polarity. Here is an article with some basics of power jacks.
https://learn.sparkfun.com/tutorials/connector-basics/power-connectors
You can order an adjustable power supply with a bunch of swappable tips on Amazon.
Remember to check the polarity of the plug too. Some have + in the center pin, others have -
I'd never heard of this before, but without industry standardization I can see it happening.
I didn't realize Satan designed electronics.
As it has been mentioned, it's a barrel plug, but there are dozens of barrel plugs of different sizes, some even have the same outer size but the receptacles for the central pin have different diameters.
Check the polarity and voltage, and try to measure the diameters if you're buying online.
If you're buying locally, take the lamp with you and ask for advice to the seller.
Yeah. That’s what I’m worried about. I think I might have to contact the seller I bought the lamp from on Amazon and see how it goes. Otherwise I’ll take the lamp to the electronic store near me and try the pins one by one.
Luckily there are only as many different barrel plugs as there are imperial units. /s
Good luck ;-)
Barrel plug, same as you'd find on the power supply for many laptops etc. You need to know:
the voltage/amps of the adaptor (may be listed on the bottom or side of the lamp). It must be the matching voltage, amps can be higher than listed
The barrel size (outer diameter, inner diameter, length), can be measured with calipers
Polarity of the tip
If there's an electronics repair place anywhere nearby they might be able to figure out the barrel size etc for you.
See also:
As it has been mentioned, it's a barrel plug, but there are dozens of barrel plugs of different sizes, some even have the same outer size but the receptacles for the central pin have different diameters.
Check the polarity and voltage, and try to measure the diameters if you're buying online.
If you're buying locally, take the lamp with you and ask for advice to the seller.
Already great answers here about what the terminology is.
If you want my advice on what to do, I would buy a "universal AC/DC" power adapter that comes with a bunch of interchangeable barrel plug sizes and adjustable voltage. Something LIKE this: (amazon) https://a.co/d/bnlGn8I
If you set it up right, it will probably get you going again. The side benefit is that you can "guess and check" for the right barrel plugs for any you might need in the future in case anything else needs one.
If you're in the us, Best Buy has a few different multivarrel options where you can also change the voltage from 3.3v to up to 12v depending on what voltage the lamp is. Best buy is not the only store, you can get them online as well. I just say best buy because I needed one for my li-ion charger.
oh that’s cool. The lamp is 5V/1Amp. I’m thinking of of going to Micro Center first and then try Best Buy.
Yup the universal charger I bought also has that setting. Just make sure to read the packaging on it but either of those places should have them. Just make sure to read the packaging and double check it'll output that voltage and amperage.
Is there any brand and/or sticker (or embossed voltage information) on this lamp? Anything to ident it? Because i've found similar ones, but they're modernized, using USB ports rather than the old barrel plug. The information found on that sticker or any information, really is more valuable than the picture, because we can probably guess exactly what you need to buy down to the voltage.
Yeah! the other end of the barrel plug is a usb port. I found the amazon listingof my lamp and it is 5V/1A, 3Watts but the diameter of the barrel plug is not mentioned in the description.
Barrel
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