Successfully replacing a halogen bulb with an LED

While clearing out an old cupboard prior to painting a room we recently uncovered an old desk lamp that had stood the test of time and was sitting all forlorn for want of a new bulb. Do we simply replace the bulb with another 12V halogen - or do we try one of the new LED bulbs and see how they go?

Well, like many others, we tried the LED route - but it was not quite as simple as we thought it would be....

Choosing a replacement LED
A typical desk lamp is fitted with a 12V 10W or 20W halogen bulb that consists of a glass envelope with two pins coming out of one end.  The whole assembly is known as a G4 bulb.  Therefore, to choose an appropriate LED replacement we need to look for LED G4 bulbs.  But there are lots of different types, designs and styles...

On top of the different styles you've also got to be a little smart when choosing the LED bulb as manufacturers will overplay their light output so a little research and perhaps not choosing the cheapest replacement will often yield better results.

The tiny LED chips on these units - the yellow-and-white blocks in the picture above - come in one of three types known as SMD 5050, SMD 3528 or SMD 3020.  These numbers refer to the size of the chips - for example the SMD 5050 chip is 5.0mm x 5.0mm and the SMD 3528 is 3.5mm x 2.8mm.  One other point to note is that the 5050 chip is capable of three times as much light as the other two simply because they are fitted with three LED chips whereas the others are only fitted with one.

Armed with this I chose a G4 LED bulb from Amazon. It cost me a couple of UK pounds to buy.

Here it is pictured with the bulb it is replacing:

Fitting  the replacement bulb was easy - just undo the three screws holding the protective glass shield, remove the glass shield, pull out the halogen bulb and push in the LED replacement.  Testing the bulb proved troublesome though - it flickered.  And the light levels were much less than I was expecting.

Why is this?

Simple.  The LED is a diode. A diode only conducts electricity one way.  In our simple desk lamp, where a 12V transformer fed the old halogen bulb directly, the bulb was lit with 12V AC.  For a halogen bulb this doesn't matter - it just gets hot and glows.  However an LED replacement will only light up for half of the AC waveform. It will be off for the other half - and this on/off every half cycle will be noticed as flicker.

A note to readers: Opening the base of these lamps as I describe below could expose potentially lethal voltages that can easily kill. If you are not confident about working with mains voltages then please do not attempt the modifications below.  If in any doubt, ask a qualified electrician.

Improving the light quality
To get round this, I built a simple bridge rectifier and smoothing capacitor on a bit of stripboard with spare parts I had around. This should provide a decent 12V DC supply capable of lighting the LEDs properly.  Here is the circuit diagram:
And here is a top-and-bottom view of the finished circuit.  The rectifier is a simple 1A 50V bridge rectifier, the capacitor is a 47uF 25V Electrolytic.  Carefully placing the two components and four wires on a stripboard meant I did not even need to cut any strips.The yellow leads are to be connected to the transformer and the red and black leads to the LED in the lamp housing.

Taking the base of the lamp apart shows how the transformer is connected - the two black leads with eyelets were connected to the metalwork connected to the lamp housing.
First of all I tested the rectifier before installing it in the base of the lamp.  That light was much better - no flicker and plenty bright enough.
Next, I threaded an insulating boot round the rectifier so that it would not touch anything and cause a short.  Then I cut off the eyelets on the transformer's black wires and, using a simple screw terminal block, connected the yellow wires from my rectifier to the black cables from the transformer.  I then crimped fresh eyelets on the red and black wires from my rectifier and screwed these to the base of the frame that supported the lamp.  You can see all this from the next photograph.

Finally, I tucked the rectifier and leads into the base and re-assembled the base making sure no wires were crimped or exposed.  After fully re-assembling the lamp I tested it again and this time success.  Even with the camera flash, the LEDs show up bright and clear - without any flicker.
After adding a rectifier and simple smoothing capacitor I have successfully replaced a 10W halogen bulb with an LED bulb that will last a long time and gives out a very pleasant light to work under.  Not only that, the head of the lamp will no longer get hot, as the LED only consumes a fraction of the power of the halogen bulb.

If you read through the comments below, I've had a question asked by one reader regarding making a rectifier for a larger project involving 10x 2W LEDs in a chandelier.  In this case you may find that the best route here is to get a proper LED Driver to complete the job as this will provide better safety against heat, short circuits and installation concerns.  These are also designed to be installed above the ceilings where chandeliers such as the one my reader is adapting are usually installed.

There's no such thing as a Free Browse ...

The old saying that "There's no such thing as a free lunch" has plenty of meanings in life as many of you will be aware.  But it also applies to you and your activities when browsing the 'net.  Virtually nothing you read about or surf is 'free'.  Even this humble little blog, tucked away in a remote corner of Google's Blogger service is not 'free'.  Oh, sure, it's free to use, but the cost is not quite ... how shall we put it? ... 'free' to you.  You're likely here because you're interested in the content of my blog.  But the fact that you are interested in this information is itself of interest to advertisers and marketers who use this info to build up a profile about you and your habits that they then sell on.

Let me tell you how.

Money can be made from your surfing habits on the Internet in a number of interesting ways:
  • If you choose to pay for a subscription service (such as a subscription to a news web site or a film provider) you are paying the web site owner directly.
  • If you buy something (such as from Amazon or ebay) some of the money you pay will go towards the cost of the web site.
  • And if you use Social web sites that encourage you to share information (such as search engines, Facebook, MySpace etc.) that social site makes money by selling information about you 
But, you might think, Facebook is free, isn't it?  And how on earth can Internet searches make money?

Sit down. Prepare yourself.

Facebook is certainly 'free to use' in that you do not have to pay to use Facebook apps to play games, or to answer questions about which books you've read, or which countries you've visited.  But what you are doing whenever you use these apps is giving away details about yourself to the companies that write these apps.  These companies can then sell this information to advertisers who use it to target adverts to you.

But Facebook doesn't only limit itself to these Apps.  Remember those Social buttons that you click on to 'Like' or '+1' a product or article? These are supposed to connect with websites that focus on building social relationships (like Facebook, Twitter, and LinkedIn) and to help you share content, interests, and activities with your friends and contacts.  However, Social Buttons also allow these same social networks to track your activity across the internet whether you click on them or not.  This information is worth money to them as they then sell this on to their customers.  You can, for example, read what Facebook does with your data by reading their Data Use Policy.

Then there are Advertising networksThese share your information across different sites.  They collect data, display advertising, place cookies, and do a variety of other things as a paid-for service for their clients. Typically, the customer (not you - you're the product!) who buys from an ad network is a publisher who displays targeted adverts and marketing on many different websites.

Finally there are Tracking companies who provide individual website owners with tools to analyse and monitor visitors to their sites. These analytical networks collect data on how long you stayed on a site, what you clicked on, where you went before and after your visit, and more.  They'll track which words or phrases you used on a search engine to get here.  Even the path your mouse took to get to a button.  All of this is used to build up a profile of you, so that advertisers can target you with 'relevant' advertising - or to streamline the performance of a web site to make you click quicker on a link to an advert.

To give you an example, one person found out his wife might be pregnant from a peculiar source: an online ad. “I was seeing adverts for pregnancy tests every time I turned on my laptop,” says the 28-year-old. “I turned to my wife: ‘Is there something you’re not telling me?’ ” She had been using his laptop to research pregnancy tests.

This experience is becoming more common and, unfortunately, this is an integral part of your online life.  Bec­ause of this, your browser now knows as much as about your life as you do – occasionally, as the chap above found, it knows more...

Enough, already.
Ok.  So you're not going to stop this from happening.  There is just too much money and too many users involved.  But you can reduce how much information these companies gather about you.  Just a simple thing like not using the apps on Facebook can go a long way to cutting down what information is passed to these companies.  Many of you will also use tools such as 'ad blockers' in your browsers.  These stop certain adverts from displaying in your browser, but crucially will rarely stop your information from being gathered and stored away (think of your data as being harvested).

Recently I came across a product from a company called abine called DoNotTrackMe (When I first wrote this article the product was called DoNotTrackPlus.  The images and discussion below is using the older product.  The new version does the same job but more efficiently).  This free product works as an add-on to your browser and it watches out for advertising companies and social networks looking to gather your personal information from the web sites that you use.  Have a look at abine's web site to learn more - and download and use it to greatly reduce what the Internet world can harvest about you.

Is it effective?
I've been using it for a couple of months now and all I can say is that browsing seems quicker, and I see fewer ads on my sites.  Even my Facebook page doesn't show any ads.

The picture below shows Do Not Track Plus running on my Facebook page:

And this picture shows the Reuters site.  Note the 'Facebook 'Like' button.  It's blocked from tracking me, but I can still click on it to 'like' something.

Try this software.  As I said, it's free, it seems to work and at least for me, I feel it improves browsing and privacy.  And we all want some of that, don't we?

Let me know what you think.  This week, as you browse the internet or answer those questions on Facebook, keep in mind that when you're not paying with cash you're paying with your personal information....

Since publishing this Blog I saw the following nugget on the BBC news site claiming that ... "There are on average 14 tracking tools per webpage on the UK's most popular sites" and that European legislation was being proposed to control this. Read more about it here.

I have also had comments made on other forums about why I am promoting a 'free' application (DoNotTrackPlus) when I am warning my readers in the same article to be careful about 'free' internet services.

Good question.

Let me set the record straight: abine, the company behind DoNotTrackMe, have this same question in the FAQ section about DoNotTrackMe, and I reproduce a section below:
"Quite simply, we rely on users liking and trusting our free software enough to try our paid solutions such as DeleteMe. You can learn more about DeleteMe here:"
So hopefully you can see that their model accommodates free use of this program by leading you to want to buy their premium, paid-for service sometime later on.