Bright LEDS

tmp3061Just for the sake of it I bought 10 LEDS from China from Ebay, not your normal run of the mill type but the new ultra-bright types they use on mains lighting. I think I paid about 20p each if that and had to wait a couple of weeks – but they are amazing.

As you can see in the photo they are meant for surface mounting but they’re not too small to simply wrap a thin wire around each end. Anyone with ANY soldering skills should be able to make use of these around the house – but the power requirements are a little more interesting than, say a filament light. Like all other LEDS these are current-driven, not voltage-driven so you have to be a little careful – never connect them to low-voltage power without a resistor or you will send them to their maker.

tmp7444The operating voltage is around 4v but the key thing is to ensure they get no more than maybe 250ma. I have a power supply with current limiting so I simply set the voltage to 6v with maximum limit of 250ma (which means the voltage will drop accordingly to ensure no more than 250ma). With 3 in series they’ll run off 12 volt with a simple resistor or preferably a current limit circuit.

The results – amazing – they do get slightly warm and I guess they should be mounted on a board with a little copper or aluminium underneath for constant operation but I can see lots of uses for these! The photo on the right really does say it all – blinding white light. At 4v, 250ma you’re looking at around 1 watt – which is exactly what they’re supposed to take – typical GU10 lights might use 3 of these – but I’m thinking SAD LIGHTING. Imagine what a row of 50 of there would look like in a row – certainly get you up in the morning for a mere 50w!

There is now widely available LED strip in a range of colours- it’s bright but not super bright – what would it be like to see a strip using these babies! The day of halogen car lights must surely be near it’s end?

There are of course no shortages of people trying to sell expensive supplies for this “new” lighting – which has in fact been around for over 40 years – just not so bright – but in fact there are simple ways to drive these – as usual, Instructables has something to say on the subject… http://www.instructables.com/id/Power-LED-s—simplest-light-with-constant-current/  though personally I think it would be cheaper to use 2 diodes (base to ground), a pull up resistor  of maybe 1k (base to +), a BC337 and a 3r emitter resistor (to ground)– but there you are…

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iPhone Camera Replacement

I have to say, I thought I was pushing my luck here.

My iPhone camera developed a blur – it wasn’t the lens cover as I’d already put a brand new back on it – it was the lens.  Apple wanted 160 quid – then I found someone to replace the camera for under £30 and just as I was about to do that I spotted this item on Ebay and I thought… why not.

Armed with miniature screwdriver I have just successfully disassembled the iPhone, took the battery out, replaced the camera, put all back together and presto – working camera. Hard to believe at that price – but it works perfectly.

The proof of the pudding is in the eating – try clicking on the image:

Image taken with replacement iPhone camera

Here’s the link for the camera:

http://www.ebay.co.uk/itm/370508824876?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

Here’s the YouTube disassembly instructions – not mine – someone took the chance before me.

Replacing iPhone camera

Lies, More Lies and Solar Chargers

Thought you might find this interesting… one of the dangers of people selling things they don’t understand.

http://www.ebay.co.uk/itm/ws/eBayISAPI.dll?ViewItem&item=251078578217&ssPageName=ADME:X:RTQ:GB:1123

In this advert is what looks like a very nice solar charger from a company called DracoTek. It offers “11200mAH High Capacity Solar power charger with flashlight

Lovely looking device- just the thing for the traveller… Ignoring the flashlight – 11,200mAH – that’s 11 ampere-hours – that’s more than an alarm lead-acid battery – and from the sun, no less.

But here’s the catch… they claim it will charge in 3 hours from the mains or 11-12 hours from the sun.

To charge an 11aH battery assuming 100% efficiency (impossible)  – you need 11 amps for an hour so let’s say 12 amps – Or  6 amps for 2 hours, or 3 amps for 4 hours etc…. but the spec says the adaptor can only output 2 amps max.. that’s 6 hours, not 3. And solar – that’s asking a lot from a solar panel a mere 160mm by 90mm.

I wrote to them with these questions…

I have a question. According to the spec, the charge current on mains is 2 amps max. It’s an 11+A/H battery. That indicates 6 hours charge assuming high efficiency AT BEST. But the spec ALSO says it takes only 3 hours to charge?? How is that?
Will it really fully charge in under 12 hours sunshine only?

Also I’m not seeing a 5v output which would be needed to charge, say the iPhone in the example. The spec shows only 4.2v, 8.4v etc… no 5v??

The response??

“I am sorry that i can not be support with it, thanks.
Best regards
Vera”

Always check the specification intelligently before buying!