Aren't bulbs passe?
Sure, they are; but...
The recent International and National campaigns to replace the incandescent bulb with a more energy-efficient alternative is fresh in our minds. The good old electric bulb has been with us all along right from the days of Edison, the original inventor of the incandescent bulb. Over the decades it had held its own--it was simple, inexpensive and universal. Only that it was not energy efficient, especially when compared to fluoresent tubes and their smaller cousins, the CFLs. Today it is not easy to locate a bulb in an average household as a result of the 'replace the bulb' campaign.
Looking forward to the future, we can easily see that it is the era of the LED, which is even more efficient than the bulb and the CFL, its life is phenomenally longer and it runs cooler, it can work at very low voltages directly, and overall it is more reliable. Then why haven't LED lamps replaced the bulbs and the CFLs? High cost is the factor that has kept the LED lamps from being very popular.
A look at the local market reveals that 'drop-in' LED replacements for the bulb are available, but they are pricey, Indian ones going for about Rs 700 plus and cheaper Chinese imports going for about Rs 300 and up. And frankly, many of them are not bright enough, nor are their 'beam patterns' suitable for replacement in standard lamp shades. The right time for the DIY guy to try his hand.
Here is an LED 'bulb' that is inexpensive and works in most common lamp shades as the LEDs are deployed in 360 degrees. Above all, like most of our projects, this is EASY! In fact it is one of the easiest and cheapest of projects, as a 1 metre strip of LEDs and a few components are the only things you need to purchase.
HANDS-ON
Retrieve an old fused CFL from the junk box. Disassemble it and discard the glass tube part carefully. Unsolder the leads from the bayonet holder to the small PCB. You will see a bridge rectifier (four mains-rated diodes) right where the AC goes in. Either remove the diodes, or better, remove all the other components and retain the bridge on the small round PCB. Refer to our strip-lamp circuit and connect the 0.47 uF cap + bleeder resistor to one side of the bridge. The free end of the "dropper cap" can be wired to any small PCB pad and now you can wire up one of the AC mains inputs from the bayonet holder to that pad and the other AC wire from the bayonet socket to the other corner of the bridge. Remember, there is no switch here. Wire up a black and red wire each to the + and - outputs of the bridge to feed the LED strip.
Now look around in your junk box (or ask your friendly plumber!) for a suitable diameter PVC water pipe that fits into the top part of the CFL housing. Wind the LED strip around this in a spiral and note how long a piece you would need. Refer to the pics and finalize your assembly. I have used a couple of screws so that it can be disassembled easily for trying various caps etc. Once you have tested and finalized everything, the best deal would be to use hot-melt glue and stick it together. A small hole is drilled through which the +/- wires are fed and soldered to the strip. It is better to solder the leads before sticking the LED strip down. Do it fast with pre- tinned leads and take care not to overheat and melt the strip into goo! Now mark the first spiral with a scratch on the PVC pipe.
Now clean the PVC pipe with detergent and dry it thoroughly, and see that you don't get grease on it by touching it. Remove a few inches of the adhesive backing paper from the LED strip and carefully align the first spiral to the mark made earlier and begin sticking down the strip. As you go, continue to remove the backing paper and carefully stick the rest of the strip to the PVC pipe. See that this is where your "artistry" has to come into play! You will be amazed to see the whole 1 metre of the strip occupying a length of hardly 3 inches of pipe. Put a small glob of hot-melt glue at the end of the strip and seal the small hole for the wires at the other end too.
Connect up everything, either screw together or better glue together the byonet holder part and the PVC pipe section, seal the bottom of the pipe with a disc of plastic or laminate or even thermocol to keep out the pests. Remember to drill a few small holes in the disc, which, along with the holes in the base of the holder, assures some ventilation for the circuit. That is all!
Build as many as you want for your low-light needs and surely you will save some money and also reap a lot of satisfaction. In case you want a longer 'bulb', it is only an easy matter to add another half a metre or even one more metre of strip and use a suitably longer pvc pipe. If you want a stouter bulb, use a larger diameter pipe and use a "reducer" available from plumbing suppliers and glue the holder part at the end of the "reducer". This will make it easier to have a couple of metres of LED strip on a short and stout piece of pipe. As I said earlier, your imagination would suggest many more designs to you to meet your varied needs.
Now's the time to replace those bulbs with better 'bulbs' !!
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