Has anyone tried to replace an old incandescent bulb in a bike light with an LED one? I see such bulbs exist (ca. £12 on ebay) and they 'should' provide longer battery life and much brighter light, but I was wondering if they are worth the expense?
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LED bulbs
(17 posts)- Started 13 years ago by Its_Me_Knees
- Latest reply from steveo
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Posted 13 years ago #
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Hi, have you got a link?
I found this: http://www.ebay.co.uk/itm/Pk-2-6V-White-LED-MES-Bulb-100-screw-MES-Lamp-/130560966203?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item1e660a3e3b (and a few similar) but they're a lot cheaper than whatever you've found and not very bright at all.
Posted 13 years ago # -
well the listing makes them look good
If it were me I would give one a shothad a look on DX?
http://www.dealextreme.com/c/led-light-bulbs-907?page=1&pagesize=52&pagesort=price
might get a cheaper option
Posted 13 years ago # -
It probably won't work for long any way, it really depends on the electronics in side. Your dynamo is out putting a very wide range of AC voltage the electronics for this device are expecting max 9v DC.
The cheaper and simpler way is to make a bridge rectifier and find a simple way of fitting a single emitter into the body, It'll be brighter and there is no way you'll blow it.
Posted 13 years ago # -
Another issue is the beam pattern, if that matters to you. The reflector in your lamp will not be effective for a front firing LED with a lens like that. If there is a lens glass, that will work OK provided the LED is pretty much where the fillament was before.
I think it's worth a try, but only with a rectifer (cheap) to supply DC to it.
Posted 13 years ago # -
I have to say with the price a new semi-decent LED light can be bought for, with someone else doing the electronic gizmodgery for you it might be quicker and cheaper in the long run (and get you a better light) to buy a new one. You can get something pretty good for around the £20 mark and they'll probably throw in some batteries too.
Posted 13 years ago # -
'Build a rectifier'!?
Just buy one, for example:
http://uk.farnell.com/fairchild-semiconductor/mb1s/bridge-rectifier-0-5a-100v/dp/1467483
Posted 13 years ago # -
"
Country of Origin: TW Taiwan
Country in which last significant manufacturing process was carried out
"How in the 'real world' can you make something, ship it half way round the planet and retail it for 31p!!
Yeah I know. It's the global economy we're all in it together with.
Not even as though Taiwan is a low wage economy anymore.
Posted 13 years ago # -
Weight (kg): 0.0005
Just imagine how many of them will fit in a packing container!
Posted 13 years ago # -
Not intending to use a dynamo - C or D batteries in a couple of old lights (ever-ready stylee) is all I'm looking at. Did wonder about the beam pattern right enough, but prepared to see if that remains useable/legal...
From the replies thus far, I take it no-one has actually done this...?
Posted 13 years ago # -
Oops I think that is my fault, I've got dynamo lighting on the brain at the moment...
Er yeah it'll work fine from batteries a couple of good quality rechargeable AA's in C/D adaptor cases and they'll be right. If its just a "be seen" light then I wouldn't worry about the beam pattern the LED will be much more spread out but that'll just help you be seen from the sides.
Worth bearing in mind though that if its more than a couple of pounds for the bulb you'd probably be better getting a new light.
Posted 13 years ago # -
I'm intrigued by various claims along the lines of "contains fancy circuity to keep the output at the right level until the cells are completely dead". Has anyone had any experience of lights/component LEDs which keep going at a reasonable level, ekeing every coulomb out of the cells until dropping suddenly dead? It would remove the need for the winter chore of leaving lights on throughout the day on the desk until they're fully discharged, ready for recharging.
Posted 13 years ago # -
There are quite a few 'voltage boost' circuits that will give a steady 5v for -whatever- input, until the bitter end, when they suddenly drop out.
I've had some good experiences with this:
http://www.hobbytronics.co.uk/components/voltage-regulators/pololu-5v-boost-regulator
...which I'm using to supply my cheapo keyfob headcam doodat.
These are great things, you can run a 5v circuit from a single 3.7v, 1.5v or 1.2v, no problem.
Posted 13 years ago # -
You can get buck/boost drivers that control the out put at voltages both under and over the leds range. A good white led needs about 3.5v at 500ma so when the battery is >3.5v the voltage is reduced (buck) and once the voltage drops below 3.5v it is boosted to continually meet the current requirements. These are pretty uncommon because they're (relatively) expensive, not very efficient and not all that useful. Once a NIMH battery voltage drops to about 1.1v its as good as flat and the only time a buck/boost regulator would be useful would be with a 3xAA battery since the starting voltage is about 4.2v and the dead voltage is 3 volts.
TBH nimh don't really need to be discharged fully and its harmful to Lithium batteries.
Posted 13 years ago # -
"...the only time a buck/boost regulator would be useful would be with a 3xAA battery..."
I've a couple of casings for 3*AA incandescent lights sitting about which I was wondering about doing something with, though would probably use the casing for circuitry and have the cells sitting somewhere else (probably bolted to the downtube bottle bosses, where I can't put a bottle as they tend to be wheeched off by the cuffs of my shorts) so that I can still get some use out of some older cells or those which were stranded as singles after a pack of four was used to power a three-cell light.
Posted 13 years ago # -
I've got a couple of drivers going spare they're about the size of a penny and a few mm deep, you could probably find a home for one and still keep the batteries in the casing. They are only Buck regulators but there isn't really much power left in a AA battery once it drops to about 1.1v and even then the regulator swaps to what is called direct drive mode where regulator circuits are bypassed and the power is taken as is from the battery.
Posted 13 years ago #
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