How interchangeable are AC adapters commonly used for electronic devices? I’m replacing my telephone and I’m wondering whether I should throw the old adapter away.
Kidding. Of course, I should throw the damn thing away. But just out of curiosity, what are the odds that it could be re-used with another electronic device? Has a box of old AC adapters ever done anything more glorious than take up space?
Are AC adapters adequately labelled? Meaning is the information printed on them sufficiently complete and accurate so that you could use them for an unrelated device?
Wikipedia: Many electrical products are poorly labeled with information concerning the power supply they require, so it is prudent to record the specifications of the original power supply in advance, to ease replacement if the original is later lost. Careful labeling of power adapters can also reduce the likelihood of a disastrous mixup which could cause equipment damage. Ookay, but how would one acquire all of that information (5 parameters, if you believe wiki)? I want details! Practical knowledge! Lessons from experience! Reports of near disasters!
I always save them and find uses for them all the time. Most are usually labeled with DC voltage and amperage, and if not, can be measured with a multimeter.
I use them for kid’s toys, motorcycle battery chargers, custom projects.
But then again, I save and re-purpose just about everything.
As mentioned, Volts and Amps are labeled on the AC adapter. The polarity (which connector is positive and which is negative, or whether the output is AC) is also labeled. If you need opposite polarity, or a different connector, you can cut off the existing connector, and replace it with the right connector, or the same connector with the leads reversed.
Voltage regulation I can’t help you with. You could measure the unloaded voltage, and that would tell you if it’s much higher than the labeled voltage, but I think that’s still not enough information.
Voltage regulation in your typical wall wart is minimal to nonexistent. There may also be a high amount of ripple present. Usually though if you match up the amperage of the wall wart close to the original device’s wall wart the substitute will work well enough. Most wall wart powered devices also aren’t all that terribly picky about the supply voltage coming from the wall wart.
However, the key word there is “most” and it is possible that you could have an unregulated wall wart that puts out a fairly high unloaded voltage that could damage a low current device that isn’t designed for that voltage.
Most of the time though, if you match up the voltage and get the amperage reasonably close it will work well enough and you won’t have a problem.
I’ve seen a few over the years. It’s very annoying when you have to replace one and it’s burned out so you can’t even measure the voltage to find out what it should be.
Yup. I once burned out an electronic keyboard (musical) by hooking it up with a wall-wart that ALMOST fit, enough to not fall out of the power socket but apparently more than it was designed to withstand. I got about two measures of a song out of it before I smelled that melting-wire smell and yanked the plug out of the keyboard.
I hear you, man. Well, I was initially going to say RTFM, but then I remember a used device I have without a manual and some real problems finding a suitable wallwart. Possible the internal connector is messed up, but it’s a challenging housing to open up without having done the easiest troubleshooting steps first.
How difficult is it, exactly, to find an exact match for some of the more obscure connectors? I imagine all companies source them from, essentially, a catalog which might be willing to do business with an individual (maybe minimum purchase for a $0.03 part shipped from a US distributor, but you know, maybe buy 100 and sell them off book to fellow hobbyists).
Swapping polarity just takes a steady hand with the soldering pen/iron, as I know it, but maybe I’m missing something.
This was true, back in the old days.
Now, more and more power adapters are a complete AC-DC switching power supply - they have to be, to meet Energy Star standards. These are very tightly regulated, and usually come in standard voltages - 4.1v, 5v, 12v, etc.
Well, you’ve got the data, so why not anecdotes? I’ve been reusing them all my life. As long as they aren’t too out of spec and the polarity is correct, the risk is pretty low. Many battery-powered electronic devices already have a large discrepancy between the adapter and the battery output. And not in favor of the batteries, either, as you would expect (as no battery stays at their stated voltage very long–they decrease over time).
The only ones I am wary of are the ones that go much over an amp. But those seem to be relatively new to the “wall wart” form. Most of the ones I have a separate cord on the end. You see them a lot as power adapters for laptops.
It might be worth mentioning that, while uncommon, there are wall warts that provide low voltage AC current. Plugging a 12 volt AC adapter into a device that wants 12 volts DC can be – interesting. Small 8 port network switches don’t work well if the magic smoke gets released.
The amperage rating on the wall wart is the max it’s rated to deliver, however it will only deliver as much as the device “pulls”. So a wart rated at 700ma can power a device that requires no more than that. A device requiring 250ma can use a wart rated for more provided the voltage is correct of course.
Your basic transformer/rectifier/capacitor wall wart is rated for X voltage AT Y amps. If you load it lightly, the voltage can be quite a bit higher. I learned this the hard way when I ruined some device by using a high-amp rated adapter on a low-current device. Even though the rated voltages were the same, the unloaded voltage was too high, and fried the device.
I agree, but within limits, and I should have stated such, what I posted is true. But using a 5a wart to power a 500ma device is not a good idea. A 800ma wart and a 200ma device should be good.
I had a device which used (more like: ATE) 9v. batteries. I also save old “warts” (love the name!) and found a 9v DC 5 mA unit, and rigged it to a 9v battery terminal I had. (I have at least one of all kinds of obscure crap - when I die, somebody’s going to have a real mess to clean up).
It fried the device pretty much instantly.
Yes, I did check polarity.