Computing stuff tied to the physical world

New USB power option

In Hardware on Mar 2, 2011 at 00:01

Ah, I’ve finally found a nice little CE-certified power supply for USB:

Micro usb

Extremely small (i.e. easy to ship), and very efficient. This thing will provide up to 1000 mA at a stable 5V level. Perfect for JeeLinks, JeeNode USB’s, and Arduino’s – or any other USB devices for that matter:

Dsc 2461

The power consumption when idle is a mere 0.20 watt, i.e. less than 1 mA of mains current. When plugging in a JeeLink, this increases to 0.32 watt, which is pretty phenomenal actually: the difference is 120 mW @ 5V = 24 mA, just about exactly what the JeeLink consumes with an ATmega running full-power and the RFM12B in receive mode.

I’ve added it to the shop and also added it as option to replace the AA board in the JeeNode Experimenter’s Pack in case you’d rather run off mains power.

  1. Looks fantastic. i have also been trying to source such a power supply. I found there is not much choice in usb power supplies from UK electronic stores ( Where do you source this adapter from? and is it available with a UK three pin plug? Thanks, Glyn

    • Comes from a Dutch wholesaler. No UK or US plugs, sorry.

    • @Glyn, UK plug? You just need to hit it with a bigger ‘ammer ;-)

      Seriously though, it is a little annoying. I mean, how hard could it be for the whole of Europe to adopt our standard? :o)

      Anyway, I was recently rather impressed with the charger for my new HTC Desire, as modelled here

      What you can’t tell from that picture is the regulator module and the plug faceplate are separate, they slot together and turn to lock. The regulator model is good for 100-240v input and 1A 5v output, so “foreign” faceplates must be available. The UK model is called the “TC B250”, it would be good to know if it is possible to buy an adapter with a full set of plug attachments.

      That all said, I doubt JC would even get a UK faceplate to fit into a bag without making a hole in it… Now if only the people that invented that folding UK plug would pull their finger out!

    • And I obviously intended to write “hole” and not “whole”, it’s way to early for my brain!

  2. Do you have the dimensions of it?

    Could be useful hard wired into the mains.

  3. Open it up, Open it up!

  4. Really great! But Yes, open it up! What’s under the hood? Id’ really like to get same components on a PCB for some of my Jeenode boxes!

  5. It seems to me that he’s got it from the dutch website

    I already have on of those for some time and got it from them. See this link:

    You can of course try ordering one and open it up, I havn’t tried that because it works fine for me. So I don’t know if it’s glued or just a simple click system.

  6. Thanks!

    For those who’d like to have a small but quite powerful power supply (for LEDs+Relays+…), I’ve found this :

    It comes from MORNSUN (china) and exists in 3,3 5V and more :

    They are really tiny for the current supplied.

    • Looks interesting! Would it make sense to try and get this into the shop? I’ve been wanting to add some sort of low-power unit for in-project use. It does require extra care since there is mains AC involved.

  7. Just one warning: these are switching power supplies, so no transformers, no complete separation between the mains and the output, no earth connection. I tried similar units (coming from various sources as battery chargers) and after burning some circuits, surprise ! I measured a high ac voltage between the output and earth. This leakage voltage is therefore well capable of making damages the connected circuit, as I unfortunately experienced (one low-power mainboard and another circuit). Generally, these kind of power supplies are perfect if used with standalone stuff requiring no external connections (such as a cd-player or a game or, in this case, a standalone jee-link) but if you need to interface your circuit to other circuits there may be risks. At least, this was my experience with the units I own and I think it is good to know.

    • Are you sure? Most power supplies have inductive or capacitive isolation, rated to 2kV or more. In fact, I doubt any of these supplies would be allowed and get CE certification if this weren’t the case.

  8. Of course the units I tried are stabilised 5V output @ 1000mA !

  9. Yes, unfortunately I’m sure. Sure this does not mean that all this type of power supplies are the same ! I tried two different models, however now I cannot say if these are CE or not. Just test the one in your hands, probably it has not this issue.

  10. @glyn,

    dealextreme has a few “USB charger in UK plug” type devices. The small ones look like the one supplied with the Kindle.

    This one can output 1000mA, but do check the comments, some people complained about the heat at 1000mA, so not sure about efficiency.

    Also, CE marking can be spotted on some of the photos.

    Cheers, John

    • Great to see some options for UK. DealExtreme also have several US adapters. You’ll have to get it direct from them though, I’m only putting AC mains related stuff in the shop which comes from EU or US distributors.

  11. I’d be slightly skeptical about a CE marking from Cheap Chinese stuff, I’ve taken apart some truly shocking replacement laptop PSUs!

  12. @TankSlappa – You get exactly what you pay for, you’re absolutely right. Everything people complain about, heat, efficiency, stability, output voltage, isolation, etc… is down to what you can get away with to make a profit at that price point – including fake CE markings if that helps sales.

    Question is, how different is the amazon unit sold at 16 quid?

  13. @John,

    I take your £16 and lower it, by about £12!

    Whilst looking to see if the HTC adapter I received with my new phone was available with the alternate face place (it comes in two pieces) I discovered that the UK model is called “TC B250”, the EU model is called the “TC E250″… Same regulator module, just different clip on face plate… I did a google and found the “TC E250” on amazon… £3.75!

    Best I’ve managed for the UK one is round the £7 mark (the ones listed at £4 have seriously high P&P)

    Don’t worry about the “microUSB” labels, that’s what the phone uses, the adapters themselves have a standard USB socket that provides 1A. They just have a USB to MicroUSB cable. If these are genuine HTC adapters, I can certainly vouch for the UK model. CE marked and doesn’t get at all warm in use.

    It would be great to be able to get one of these adapters with both UK and EU faceplate, and not even bother with the MicroUSB cable, I’m sure we’ve all got several if we needed them!

  14. I’ve got a couple of these recently. 4,99€ in the supermarket next door, so perhaps not as good as the one above, but actually twice shorter with stated 0.7A max. However until now, I was wondering if these could really be plugged in 24/7 with JeeNode attached? I remember some 220V GU10 48 LED lamp I used 12h/day that lasted 5 days! I suppose in both cases electronics is not so different.

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