DC Power Adaptor Related Question - Is it safe to use one with a higher amperage - Page 1
Forum section: electronics / general

author: Deodand2014
author_rank: Regular Contributor
timestamp: February 10, 2019, 01:48:15 pm
content: I've recently come into possession of a second hand TDK Icubic clock/radio/ipod dock (Pre-Lightning connector). The original power adapter (and the remote) had been lost. So instead Cf a 12v 1.2 amp DC supply it's currently plugged into a 12v 2amp supply which I got along with the radio. What I want to know is that if it is safe to continue using it like that or look for something close to the recommended amperage.The DC adapter it's plugged into is branded 'CS' or 'CS Power Supply' and without tearing it apart, the only good thing I can say about it is that there is a ferrite on the power cord close to the jack. A picture of the information printed on the adapter is attached.

author: james_s
author_rank: Super Contributor
timestamp: February 10, 2019, 05:14:24 pm
content: A device will only draw as much current as it needs, you could use a 10,000A adapter and it would make no difference.The one potential issue is older style unregulated adapters, the kind with a heavy iron transformer in them. Those will typically put out the rated voltage at rated load, with load that draws less current the voltage can be significantly higher.

author: amyk
author_rank: Super Contributor
timestamp: February 10, 2019, 10:33:10 pm
content: The other special case to be aware of is the current-regulated supplies of the type often used to power LED lighting or charge lion cells; the former will usually be marked with a voltage range as well (e.g. 9-30V, 300mA) while the latter will have a 4.2V current-limited output. Those definitely should not be replaced with one of a different current rating, unless the application is known.

author: tooki
author_rank: Super Contributor
timestamp: February 10, 2019, 11:58:27 pm
content: But are those ever seen as simple wall warts? I don’t think it’s helpful to confuse a true beginner (which is the case here, given the original question) with something only encountered as power supply modules or as dedicated battery chargers, not as simple wall warts.

author: james_s
author_rank: Super Contributor
timestamp: February 11, 2019, 12:24:02 am
content: Well we can simply this and just say the pictured adapter is virtually certain to work just fine, 1.2A vs 2A is not a huge difference. I would not hesitate to use it.

author: Brumby
author_rank: Unknown
timestamp: February 11, 2019, 12:26:42 am
content: For the size and current rating - and the fact that the input voltage is given as 100-240V - it is going to be a switchmode supply. That means the output voltage will be regulated, so that should be fine.Current capacity of 2A means it iscapableof delivering up to 2A - the load will dictate exactly how much is drawn. Again, this is absolutely fine.In the off chance that this supply needs a minimum load of some sort to operate correctly, I would think that any load that has a need for a 1.2A supply will provide a more than adequate load for a 2A supply. I doubt this would be an issue - but if it were, then I would expect this new supply will work quite happily.In short - you should be good to go.

author: Brumby
author_rank: Unknown
timestamp: February 11, 2019, 12:27:53 am
content: Quote from: james_s on February 11, 2019, 12:24:02 amNeither would I.

author: james_s
author_rank: Super Contributor
timestamp: February 11, 2019, 12:37:02 am
content: Oh, one last thing, do check that the polarity is the same. The one in the picture is center positive as are most, but not all. I've seen several pieces of gear damaged because someone tried using a power adapter of the wrong polarity. Why it isn't standardized I really don't know. Hindsight I guess.

author: Deodand2014
author_rank: Regular Contributor
timestamp: February 11, 2019, 03:02:50 am
content: Quote from: james_s on February 11, 2019, 12:37:02 amI've double checked that before plugging in and radio/clock/ipod dock is center positive. I will fault the maker for embossing that information on the back in very small writing. Trying to get information on the switchmode power supply, googling the model number bought up lots of pages on security cameras!Can anyone point to a page with a good listing of what the markings on the power supply mean?

author: james_s
author_rank: Super Contributor
timestamp: February 11, 2019, 04:19:43 pm
content: Which markings are you not sure about? The center positive/negative one is pretty obvious once you look at it, and input and output voltage and current ratings, that's about it.

author: TimNJ
author_rank: Super Contributor
timestamp: February 11, 2019, 05:18:24 pm
content: Are you talking about the symbols on the bottom?From left to right:UL mark: This product complies with UL safety standards. That means it won't fail and zap you.FCC mark: This product has passed FCC electromagnetic emission testing.CE mark: Declaration of conformity for EuropeDouble insulated (concentric squares): 2-conductor input, no earth, with sufficient isolation to be safe under fault conditionIndoor use only (house): Only use this inside!WEEE mark (trashcan): Electrical waste initiativeDon't worry about them too much. Just means it's been been approved by requisite regulatory bodies.

author: james_s
author_rank: Super Contributor
timestamp: February 11, 2019, 05:26:17 pm
content: Too often these days it means some no-name manufacture in China has printed up a bunch of labels with those symbols on it.

author: Zero999
author_rank: Super Contributor
timestamp: February 11, 2019, 05:29:51 pm
content: Quote from: james_s on February 10, 2019, 05:14:24 pmUntil a fault occurs, resulting in a huge fireball.Of course a device will draw only as much current as it needs, but if the current rating of the adaptor is huge, compared to what the device was originally designed for, then a fuse is essential to provide protection against fire, under fault conditions. For low currents, under 3A or so, it's not an issue, as the current limiting and thermal protection inside the power supply will suffice.

author: james_s
author_rank: Super Contributor
timestamp: February 11, 2019, 05:36:20 pm
content: Sure, and I considered mentioning that, but wall warts delivering more than about 5A are exceptionally rare, 3A is about the limit with common ones.When you do have a fault condition with a high current low voltage source you're generally not going to get a fireball, usually some smoke as a PCB trace becomes a fuse. Been there, done that.

author: Deodand2014
author_rank: Regular Contributor
timestamp: February 12, 2019, 11:17:49 am
content: What I was really wondering about was the 'Efficiency: V' marking.

author: amyk
author_rank: Super Contributor
timestamp: February 12, 2019, 12:51:13 pm
content: https://www.cui.com/efficiency-standards

author: TimNJ
author_rank: Super Contributor
timestamp: February 12, 2019, 05:58:41 pm
content: Quote from: james_s on February 11, 2019, 05:26:17 pmI'm not sure if this is really true. Companies which ship power supplies with their products want to see traceable agency certifications/approvals (CB reports). I can't imagine that there are too many which will turn a blind eye to that. I'm also not convinced it's even in the power supply manufacturer's interest to slap fake approvals on their products. I imagine they could get in some pretty serious trouble for that.

author: james_s
author_rank: Super Contributor
timestamp: February 12, 2019, 06:26:20 pm
content: Quote from: TimNJ on February 12, 2019, 05:58:41 pmI haven't seen one (that I know of) shipped with a reputable product, but there are countless no-name widgets available direct form China that have fake markings on them. Some are outright counterfeit passed off as genuine Apple, Samsung, etc. If you buy a $2 wall wart from China there's a good chance it will not have actually passed UL and similar testing.

author: Deodand2014
author_rank: Regular Contributor
timestamp: February 18, 2019, 01:18:21 pm
content: I visited a flea market on the weekend and picked up a second hand 12v 1.5amp DC power adaptor which definitely fits the 'Wan Hung Lo' description. Made by a company called 'Shenzen Honor' it's liberally plastered with regulatory markings, way more than I think it needs (I will take photographs tomorrow.). But it has made one major change to the radio. With the 12v 2amp adapter I was given with the ICubic (See the picture attached to the OP.) I was only able to pick up one station (96.1 fm (at 96.00)) clearly and the auto channel sweep function did not work. With this adapter plugged in the auto channel sweep is working as it should and all the stations I would normally pick up are coming in cleanly. I'm guessing that the supplied adapter may not have been properly shielded and was dumping interference into the airwaves.

author: Deodand2014
author_rank: Regular Contributor
timestamp: February 18, 2019, 11:33:26 pm
content: Here are the photographs of the 'Shenzen Honor Co. Ltd.' 12v 1.5amp DC power adapter I mentioned in the previous post. Of the power adapters I have this has the highest density of regulatory markings I've ever seen. On the other hand on the basis of how the radio is performing now, I'd say someone got the shielding right.

author: TimNJ
author_rank: Super Contributor
timestamp: February 21, 2019, 03:06:52 pm
content: Quote from: james_s on February 12, 2019, 06:26:20 pmWell. I got curious. My brother bought an insanely cheap 90W adapter on Ebay several years ago. I believe it stopped working. (Big surprise!)On the outside, we see a bunch of markings, but they're all basically meaningless. There is an FCC mark, but that's just a declaration of conformity, similar to the CE mark. By themselves, they don't really mean much. If they are claiming FCC conformity, per Part 15, one glimpse at the inside reveals that would be complete BS.Not a single line filtering component in sight! No X-Cap, no common-mode-chokes (on input or output), no MOV, and just one dinky fuse! Craziness. One lightning event and this thing is toast.And the PCB is such poor quality that it snapped in half upon opening.I guess this is what you were talking about! I wonder how many of these they sell?

author: Deodand2014
author_rank: Regular Contributor
timestamp: February 23, 2019, 05:43:52 am
content: That looks like the power adaptor the shop that sold me a second hand dell laptop supplied. I've been on the lookout for something better ever since, but all Amazon brings up is items that look just like it.

author: Halcyon
author_rank: Unknown
timestamp: February 23, 2019, 06:50:58 am
content: Quote from: Deodand2014 on February 23, 2019, 05:43:52 amMost electronics stores sell "laptop power supplies" which support multiple connector types and voltages.For example:https://www.jaycar.com.au/144w-laptop-power-supply-12-24vdc/p/MP3471

author: james_s
author_rank: Super Contributor
timestamp: February 23, 2019, 07:25:06 am
content: Look on ebay, I've bought used OEM laptop power supplies on several occasions.