Here is one useful trick I invented when looking around the transformers/power supplies I had.
NOKIA ACP-7 Europe Standard Charger (Original) has a specification of 230 V, 50 Hz, 4.8 VA. Output 3.7 V, 355 mA. A normal 1W white LED is driven with 350 mA maximum continuous current and typically 3-3.8V voltage drop over the LED. Those are pretty close specifications.
Next task was to verify my theory that this should work well.I took the charger and a multimeter. I found out that the charger gave around 8V output when not loaded, the promised 3.7V when loaded with the 355 mA current and around 700-800 mA current when short circuited. This would indicate that the transformer has quite high output impedance. That’s quite good for this application, meaning that some changes on LED voltage drop do not change the current too much.
First I connected a 1W LED directly to the charger output. I got nice bright light output. I measured the current, and found out that the voltage drop over LED was around 3.5V and current was almost 400 mA. The current is slightly over the specifications for the LED and charger, which is not good.
The fix to the problem was to add one 1N4001 diode in series with the LED. This increased the voltage drop (LED + diode) to be always slightly higher than 3.7V. This will mean that the charger will always put out less than 350 mA to the load. This is on the safe side on the specifications of both LED and charger.
The end result is that an old Nokia charger combined with one diode and 1W LED (with suitable heat sinkl) will make a very simple and well working mains powered LED lamp.
I Hope Everyone Has A Happy New Year! I really love this site. With all those idiots shooting their shotguns into the air you need bullet proof vests
Stop the shooting entirely. Some idiot was shooting at New Year’s eve on the small I used to do shopping often here in Espoo Finland. Very sad New Year in Espoo. Here is link to then bad news http://yle.fi/uutiset/news/2010/01/police_espoo_mall_shooting_probably_premeditated_1336412.html
I absolutely love your blog. It is a real gem. I really hope you’re not offended but did you code this theme yourself? I am always seeking to improve the look of my bullet proof vest site.
Thank you for your feedback.
The theme was coded by a professional contractor who had made similar works earlier to some other sites.
I defined what was needed in theme (to match other site parts well. I do coding myself and use other coders as what fits best for different tasks.
I hack mainly the other parts of the ePanorama.net (things I know well and have made) and leave blog theme coding to person who knows that well…
More often than not I do not post comments on blogs, but I would like to say that this post really has compelled me to do so! Thanks for your perceptive post.
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thought this would be a nice way to make my first post!
Sincerely,
Laurence Todd
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bug Party Supplies.
My cousin would really appreciate this blog post. We were not too long ago speaking about this. hehe
Hi I’d love to congratulate you for such a great made forum!
Just thought this would be a perfect way to make my first post!
Sincerely,
Laurence Todd
if you’re ever bored check out my site!
Party Supplies
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Hi. Very nice Blog. Not really what i have searched over Google, but thanks for the information.
Hi there, really awesome theme you have. Do you know where i can get it?
This there is custom made for this site.
Hello all, I just got done making my account and I really want to say hola! I’ve lurked here for a while and finally chose to join.
I am a musician deep down, however my real job involves selling business insurance. However, I am also creating my own business five day job it is so exciting. Well, in my head at least!
So that is a tiny bit from me. I hope to talk with you all and become an active participant in your website. Talk to you soon!
This is my first time
Excellent read, I just passed this onto a colleague who was doing a little research on that. And he actually bought me lunch because I found it for him smile So let me rephrase that: Thanks for lunch!
Good work, your articles are very interesting, i am glad that i googled your blog
Hello. Very nice Post. Not really what i have searched over Google, but thanks for the information.
This blog helped me explain this subject to my son. Thanks
This blog helped me explain this subject to my son. Thanks
I just wanted to thank you for writing this. It really made my day
Maybe you have even thought to be putting additional video to those website articles that can keep the visitors a little more interested? Which i suggest I simply just read by the whole page of yours also the idea is quite great but yet due to the fact that I
I have not thought of adding video to this blog yet. As the blog ad web site is now it keeps me busy enough (I do not do this full time).
Maybe some day.
informative post
Came across your site from google .You actually have some good posts on here.Just wanted to say thanks for the read and keep up the good work bud. You’ve been BOOMARKED!
Saw your blog bookmarked on Delicious. I love your site and marketing strategy. Check out my Farmville Guide if you get a moment – http://bit.ly/bqUYf4
I am currently reading it on my Blackberry and will scan it once I get home. I love your site and marketing strategy. By the way, if you get a moment, check out my Warcraft Gold Guide – http://bit.ly/dcYOCj
Hi, i must say fantastic website you have, i stumbled across it in AOL. Does you get much traffic?
Cool information! Thanks! its very useful.. =)
Hello just thought i would tell you something.. This is twice now i’ve landed on your blog in the last 2 days hunting for completely unrelated things. Spooky or what?
Useful and nice article. I am going to subscribe your blog. Thnx.
I look forward to reading more on your blog.
http://www.ePanorama.net has a good visibility in the main search engines.
That’s why people find here often.
Quite a bit of traffic. I need to think to get a more powerful server some day.
See, everyone makes listings. Now, we’ve made one for you. Here are, in our judgment, the hottest all-around games on
Hi, i must say fantastic site you have, i stumbled across it in Google. Does you get much traffic?
Hows it Going, You might want to know this specific blog post is not showing up properly on my Motorola Razr. Anyway, I
Nice website. Great read. http://xbox360diyrepairs.blogspot.com
Hi man,I look the articles now,I imagine it’s wonderful,In addition I may tell you safety candles is led flameless candles,you can try it,considering the fact that the led candles is health and safety.
LED candless are safety candles and good idea in many applications.
I have also read that LED candles can have on hidden safety risk when combined with stupid people.
There are incidents where some people have used matches to light up the LED candle light a normal candle.
According the article I have read the burning LED candle look pretty much like normal candle for some time
(clear plastic on top of LED burns prety nicely), then it starts to burn more heavily and finally explodes throwing burning part around.
The thing that explodes in them is the lithium battery in them heating up too much.
Blog looks really good mate, keep it up! Inspires me to keep building a following mine for mine.
How do people put together such great blogs!
Nice work man. I found you on google! 
>>Find Cheap iPad…
Of course, what a great site and informative posts…
Just thought i would comment and say neat design, did you code it yourself? Looks great.
Hi man,I look over your articles now,I feel it’s good article,Thank you for sharing.
The site look is partially own design and partially made by some professional designers.
Hi guy,I view the articles here,I imagine it’s good article,Thank you for sharing.
Hi guy or girl,I seen the articles now,I guess it’s good article,Thank you for sharing.
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well… it’s like I said!