Wondering about recycling of electronic power adapters - Page 1
Forum section: electronics / projects

author: Konkedout
author_rank: Frequent Contributor
timestamp: January 03, 2025, 09:10:56 pm
content: The media has frequently mentioned the proliferation of excess old power adapters. And the EU has pushed for standardization around USB-C.I do not like USB-C so much because it seems too small and flimsy. Maybe good for a smartphone but not so much for bigger things such as a laptop. But that is not where I am going with this.I have my own collection of old power adapters. Many were my own and a bunch were the result of dumpster diving when I worked at a well-known company. In my experience, these things usually outlast whatever they were powering.For some years now, I have a laundry room "dimlight" powered by a power adapter from an old cordless phone. This has four 1W white LEDs but each one is running at about 15 mA. Our laundry room has no windows, and this light allows walking through (and other quick basic actions) with doors closed and without having to turn on the overhead fluorescents.For hobbyists and anyone who likes to tinker with electronics, many of these power adapters are worthwhile! They handle the risky part of powering your electronics; that is the AC/DC power conversion and isolation. I particularly like laptop power adapters, which typically provide 18V - 20V at 40W - 200W. Those make a very useful starting point to produce other voltages. So often on this forum, a novice wants to do AC/DC power conversion. That is a bad idea for anyone (even me who has designed many AC/DC power supplies) to do as a hobby project.Does anyone have any experience or thoughts about old power adapters being dropped off (and separated out) at recycling centers, so that hobbyists etc. can pick them up for free?

author: Zero999
author_rank: Super Contributor
timestamp: January 03, 2025, 10:46:59 pm
content: I don't know about recycling centres, but I know they're available from many charity shops for a low price.Somewhat off topic: have you tried changing the feedback divider to get different voltages?

author: Konkedout
author_rank: Frequent Contributor
timestamp: January 03, 2025, 11:25:59 pm
content: In theory that ought to be possible in some cases.The power adapter in my dimlight is unregulated with a mains frequency transformer. I do not remember the ratings, but with load current far under the rating, the output voltage is much higher than the rating. So I do not expect any regulator IC or feedback divider in that one. I assume that many of the older/smaller units may be similar.Second is that most of these power adapters are sealed shut. Either they are glued or ultrasonically welded.Third; whether it is a linear or switching power supply, the transformer (and maybe other aspects) will limit the range for any adjustment. I guess that adjusting an 18V converter down to 12V might not be too difficult if you can figure out the schematic and layout adequately.

author: magic
author_rank: Super Contributor
timestamp: January 03, 2025, 11:37:45 pm
content: Flyback switchers are tricky to convert because peak primary voltage and auxiliary supply for the PWM controller are determined by output voltage times transformer turns ratio. You may blow things up or simply cause it not to work if you don't know what you are doing.Small adjustments are straightforward, though.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: January 04, 2025, 12:42:32 am
content: I do the same, but there are some things to think about.1. "It handles the risky part..". In principal yes, and probably pretty well on supplies that were associated with higher end gear like laptops. But the low end wall warts were often somewhat dodgy. Just be aware of this and don't make unwarranted assumptions.2. They are no less susceptible to drying/failing electrolytic capacitors than any other gear and much more difficult to repair. One experience I had. A supply for my security camera system failed and I drug out a replacement from my bin. Same specs as the failed unit (voltage and current rating). But it didn't work at all with the security cameras. Checked voltage with my DVM. Spot on. Wasn't until I got the oscilloscope on it and found that the output filter had totally failed. Under load it was going to zero and about twice nominal output at the line frequency. No clean way to open it up and repair so I added an external filter and it is in service now.3. Some of these require a minimum load to operate. They will shut down if the load they are expecting isn't there.

author: wilfred
author_rank: Super Contributor
timestamp: January 04, 2025, 01:20:04 am
content: They are so commonly found these days that I wonder who would want to fund a collection infrastructure beyond the local city e-waste collection. Once it would have been easy to get some from a recycle place but now the first thought is to be worried if it is faulty and legal liability. I agree it is rarely the failure of the adapter that causes it to be thrown out. But not always and no-one will want to test them.To go off on a tangent I wonder about paralleling multiple adapters to turn 10x 1A 5V into one 10A 5v supply. I recently acquired 10 of these with some stuff I bought. They have US plugs and that is no good to me in Australia.I did try to find info on doing this but didn't find anything that gave me confidence to try it. I read things about using diodes to prevent a dominant unit backfeeding into another and disturbing the voltage regulation.Could you series connect to make higher voltages?You only need so many 5W adapters.With some other ones I would like to tweak them from a bit under 5v to 5.25 volts. I think I saw Big Clive do that or something similar but I can't seem to find the video. It wasn't the main purpose of the video if I recall correctly. That's if it was BC even.

author: Konkedout
author_rank: Frequent Contributor
timestamp: January 04, 2025, 04:04:07 am
content: Thank you, allAs for drying out capacitors: I have not seen them but of course that can happen. I remember when we did an informal life test of an enclosed switcher which I had designed. We put some full load resistors on it and plugged it into an outlet. It died maybe 6-9 months later. (Remember that it was running continuously at full load.) What killed it was the smallest (1 uF) aluminum electrolytics. All the semiconductors were still OK. We replaced the failed electrolytics and resumed the test. The next thing to fail was the (a bit larger) aluminum electrolytics. So there you go.My thinking is that nobody would test this collected "e-waste". No warranty. Get a half dozen of them for free or dirt cheap and then it is the buyer's responsibility to see how they work. I am not asking about anything which sounds like much money flowing in any direction. Rather, just a slight bit of organization so that hobbyists can swing by and pick up a bunch of them before they go to "electronics recycling". That latter process has been something of a scam (people in third world countries burning the electronics in open fires to get tiny amounts of precious metals) and causing significant pollution in the process. I quickly found this:https://www.who.int/news-room/fact-sheets/detail/electronic-waste-(e-waste)#:~:text=These%20activities%20are%20considered%20hazardous,to%20the%20toxic%20fumes%20created.So what I am proposing sounds altogether preferable.In the recycling mantra, the sequence of preferences (in order of most to least helpful) is: Reduce, Re-use, Recycle. So Re-using is better than recycling and the powers that be ought to be happy with hobbyists re-using what someone else is done with. In my experience (so far) they all seem to work OK. I do not doubt that some will be bad but I suspect that is < 10% of them.As for minimum load: Depending upon the exact malfunction which you get without the minimum load: When I started designing switchers around 1980 I did see competitor product which would shut down with no minimum load. IMO that sort of design is incompetent. I was designing switcher "wall warts" and it is totally normal for a person to apply AC before plugging it into the appliance. So that sort of operational failure would have been completely unacceptable, even in 1980. Having said that, many of my designs would go into an operational "burst mode" where you would see more ripple and noise on the output when operating without the minimum load current. But I was able to make this ripple and noise relatively mild. That in addition to making the minimum load only a small percentage of the full load rating."You only need so many 5W adapters." Yes that is true, but there is a variety of voltages and power levels. On this forum, I see newbies wanting to do their own AC/DC conversion and I am looking for good cheap alternatives.

author: lunar
author_rank: Contributor
timestamp: January 04, 2025, 07:47:09 am
content: Quote from: Zero999 on January 03, 2025, 10:46:59 pmPlaces like Goodwill do sell these, but the prices can vary. Sometimes it'seasier and better to get a 'lot' (search term) of power adapters on eBay. I.e. you would search '5V ac adapter lot'. You can get exactlywhat amperage you want, and get multiple of them. Though Goodwill is worth looking to see what they have if you happen to be there.I'm not sure what is meant by 'recycling centers', but the electronics recyclers in my area are a much better deal, though you have tobe on good terms with each respective recycler. I've seen recyclers that have a pallet sized cardboard box full of ac adapters, one forrouters, one for laptops, etc... If they are nice, they will let you dig through the box and take what you want for pennies. I used todo this for routers and ac adapters. But Gl.inet and now Openwrt One has made that obsolete for routers (it's still worth doing fornetwork switches). It's fascinating what you can find at recyclers. They often have electronic test equipment (I bought my TDS 2000series tek scope from one of them). Or proto boards from local design companies, surplus wire, etc... When I say you can get things forpennies, this usually means you give them about $100 for other things (laptops or monitors) and then they let you browse and takewhatever power adapters you want as a bonus. If you go there just to pilfer their ac adapters and network switches, they may getannoyed. You will need some disposable income. You can also give them equipment of course.Here's what I have learned about collecting power adapters. 1) You will want to get 5.5 and 2.1mm barrel plugs. This is the standard.From here you can purchase the adapter sets from china that will get you universal access to devices. (See photo attached.) 2) I stock5V, 12V and 24V, but you might also want to stock 9V. This covers most devices (and the 24V is optional.). 3) If you purchase them fromeBay, you will want to make sure the barrel plug cable is not a coax. Because if you have to solder a new barrel plug on the coax itwill be more trouble than its worth. Cables that are coax are usually a single cable, where as the divided two wire cables will have,two wires visible. You can open up and resolder the coax ones if you had to, but again, it's too much of a hassle. Start on the rightfooting, and everything afterwards will be easier. 4) I have plenty of switchers, but the older transformer ones are worth collecting aswell. These are a bit more rare, but certainly more future proof. 5) Use calipers to verify the 5.5 and 2.1mm plugs, as you will besurprised, some of them are very close but not quite 5.5 and 2.1 (and I'm not referring to the 2.5mm ones). That's most of it, Iprobably forgot one or two other things worth knowing.12V adapters are by far the standard. Usually 12V 1A.Quote from: wilfred on January 04, 2025, 01:20:04 amI have done this for a led light, connecting two 12V in series to get 24V, but it's such a mess of cables and the twoenclosures that it isn't worth the trouble.Quote from: wilfred on January 04, 2025, 01:20:04 amThis is also true, and you have to decide how many of these you need. You don't need an endless supply. I keep a small 1 gallon bucket filled witheach voltage and label the voltage on each bucket. That is enough. I try to stock higher amperages (2 or 3A) since the 1A are morecommon but can limit applications.There is some fun to be had with these adapters. I've wanted for a while to get a programmable DC Load and try stress testing some ofthese. As mentioned, you can also put them in an oven to accelerate the aging. Or as mentioned you can adjust the voltages. You canreverse engineer them (they are simple enough). They are common, so it's a rabbit hole that is accessible.

author: hanakp
author_rank: Regular Contributor
timestamp: January 04, 2025, 09:10:17 am
content: Uhm... hundreds of millions of laptops and other devices will have to be scrapped because ofMicrosoft's malicious and arbitrary decision to block their upgrade to Windows 11. That's literal mountain of needless e-waste which consumed several mountains of resources to produce. And y'all are worried about unused power adapters?And what is Europen Soviet Union doing about it? Nothing. Instead they piss off all EU citizens with useless crap likeattached plastic bottle capsand forced end of internal combusion engine cars by 2035. Like in original Soviet union, pure ideology trumps over practical measures.

author: magic
author_rank: Super Contributor
timestamp: January 04, 2025, 09:31:51 am
content: Quote from: wilfred on January 04, 2025, 01:20:04 amBecause it's dodgy. Diodes wouldn't help much, a 4.9V unit won't be damaged by applying 5.1V to it, but it will be sitting there completely idle until the 5.1V units drops down to 4.9V due to overload. The problem is that paralleled PSUs don't share current equally and some of them may even end up running at 110% capacity continuously while others do nothing.Quote from: wilfred on January 04, 2025, 01:20:04 amThis may work, if the secondaries aren't internally earthed (i.e. 2 prong mains plug). On overload one of them may shut down first and if the load continues to conduct current under reduced voltage, the others may end up charging its output capacitor in reverse. So I suppose if you want to play with multiple PSUs and diodes, this would be the place to use them - put a reverse biased schottky on each PSU's output to protect its output from reversal.

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 04, 2025, 01:01:01 pm
content: Quote from: hanakp on January 04, 2025, 09:10:17 amOr a very cheap supply of old but still quite usable PCs for Linux users!

author: BILLPOD
author_rank: Frequent Contributor
timestamp: January 04, 2025, 02:20:35 pm
content: Good Morning Konkedout, Nice collection of 'Coax/Barrel' adapters you have; I have a smaller collection that often come in handy.I have to mention an observation I made concerning your photo of the sink with an electrical outlet very close. A GFCI would be something you should consider for that outlet, unless of course there is one upstream, in which case...never mind.

author: Konkedout
author_rank: Frequent Contributor
timestamp: January 04, 2025, 09:08:00 pm
content: On the subject of output connectors. I think the barrel connectors are probably a good choice but Dell (for example) has downsized their barrel diameter.I generally cut off whatever connector is there, strip the end, and use a 5.08 mm pitch screw terminal block for input and output. This opens up the possibility of accidental reverse connection of the input, so I will use at least a schottky diode to block that, and I have used a FET rectifier (connected like a synchronous rectifier.) Given that switchers are what I tend to do, it is easy to drive the gate of the MOSFET with a charge pump from the switchnode of my switcher. By doing this, a good design will reduce any voltage drop to well less than 100 mV.I have a couple of cheap Chinese made bench supplies. The smaller one is a linear which switches transformer taps and provides up to 50V @ 3A. It is good except that the output voltage is very (low frequency random) noisy. I think the adjust potentiometer is at fault.A few years ago I made a SEPIC converter board which controls its output voltage with a dual digipot:https://datasheets.maximintegrated.com/en/ds/MAX5389.pdfThe digipot output is buffered through an op amp, and then through a resistor to the ADP1621 (I have a bunch of them) controller IC Feedback pin. That acts like a summing junction. BTW if you want to use a control voltage (such as a DAC output) to control the output of voltage regulator, a summing junction is the way to do it!! (Assuming that you are using some sort of controller/regulator IC and are not completely rolling your own design.)I use one digipot for coarse voltage adjustment and one for fine.WOW. This allows me to adjust output voltage to about 1 mV. And short term stability isROCK SOLID. There are issues with this first-try design, but my point is that this one example of a use for a home project powered by a 60W (for example) laptop power supply. I do think this is likely to be cheaper than a high grade bench power supply, at least if you get a batch of 5 boards (from JLCPCB for example) and build 2 or 3 of these.

author: Haenk
author_rank: Super Contributor
timestamp: January 05, 2025, 09:04:54 am
content: Call me an idiot, but only a few weeks ago, I dumped several hundred brand new, boxed, 5V/12V supplies into E-waste.We received them a decade ago from China, however most of the markings were chinese and certification signs were dodgy - so there was no way to bring them to market in Europe. And for company liability reasons, I was afraid to give them away for free, too. I cracked one open, and it looked OK from the technical side of it, but still.As for old wall warts - I do keep the transformer based ones, these are great for projects as internal transformer (and cost quite some money to purchase new). I usually toss the switching supplies though, keep only a few, if the voltage /amperage seems useful for projects.

author: Gyro
author_rank: Super Contributor
timestamp: January 05, 2025, 10:52:02 am
content: Yes, it's the transformer based ones that are extinct and definitely worth saving for projects where Y cap leakage (and maybe switching noise) is undesirable. Even if the internal reservoir cap has dried out, you can normally get away with leaving it and adding one inside your project. There will always be another SMPS based one.

author: Siwastaja
author_rank: Super Contributor
timestamp: January 05, 2025, 10:53:24 am
content: Quote from: Konkedout on January 03, 2025, 09:10:56 pmRemember - both in theory and in practice, smaller connector is more reliable. The larger it is, the more lever action it causes, and the more stress there is. I would say not to worry, USB-C is the result of 30 years of engineering a more reliable connector and so far the track record is pretty good.

author: wilfred
author_rank: Super Contributor
timestamp: January 07, 2025, 01:33:54 pm
content: I have one of those cheap egg cookers that boil a quantity of water to time the egg cooking cycle and when the water runs out the thing trips a thermal switch and sounds a buzzer. But the buzzer failed and barely made a squeak. The buzzer is 240V and whilst I could have made a rectified DC filtered circuit to run a DC buzzer, which is what it does inside the buzzer, I decided to gut a 240V AC to 5V USB phone charger and attach a 5v buzzer, which I already had, and put that into service.So there's one use for an old power adapter.

author: Konkedout
author_rank: Frequent Contributor
timestamp: January 07, 2025, 08:04:55 pm
content: Quote from: BILLPOD on January 04, 2025, 02:20:35 pmAs for the GFCI: We do have one or two in the house, and this one in my photo may well be downstream of one of those. I find that the wiring in this house is a bit squirrely in that there is much of this that I do not know before there is a problem.Recently I was amazed that GFCIs were $20 US for 2 of them. At that price, economizing in their use (doing a lot of sharing) makes no sense to me. For maybe $100 you could have one by every sink etc. and that is a drop in the bucket for the price of a house.

author: Konkedout
author_rank: Frequent Contributor
timestamp: January 07, 2025, 08:11:07 pm
content: Quote from: Siwastaja on January 05, 2025, 10:53:24 amI respectfully disagree. IMO you are confusing length with size in other dimensions. I think the older barrel connectors are very good. But if you think of a 100W capable cable, it is too easy to accidentally apply a large force in the wrong direction, especially when powering a larger device such as a laptop.I saw some other post referring to laptops that were trashed due to a broken USB-C connector which was the only input power port. And now I just found this:https://community.frame.work/t/usb-c-longevity-is-becoming-a-big-problem/32547I recently bought a new Rigol oscilloscope. I am amazed at its capability for $800 US. But it is powered by a USB-C connected power adapter. What do you know, the horizontal "trigger" options do not include ("Line" or "Mains")!!Hmmmm. I wonder why that is.(I am kidding.)