Tesco 3w cree

Georgeb

How many lumens do you think these light will be so I can compare them to the 3w cree?

http://www.wiggle.co.uk/p/Cycle/7/Catey ... 360019368/
and
http://www.wiggle.co.uk/p/Cycle/7/Smart ... 360022781/

How many lumens is the tesco lights?

cougie

behold the mighty Cateye :

http://yacf.co.uk/forum/index.php?topic=11751.0

Smart would be a better bet - but hey - risk £8 on the Tesco torch - at worst you'll have a nice torch round the house !

Georgeb

What does the "Part 2- Measurements mean?

cougie

Just that - measurements of the brightness ?

Just skip to the photos of the beams though - but you'd be mad to buy the Cateye after checking that out.

Georgeb

I see what you mean, not bright at all. How far away is the light from target thing on the brightness test? I have the smart and the cateye and it seems to me the cateye is brighter. Obviously not.

mtbikerboy

is it just here or has the price of the tesco torch gone up to £12?

cougie

Are you looking at the right one ? The two AA alu version ?

It was £8 in store last week. Its not available to buy online.

Brian-Mc

In Bedford Tesco the AA was £8 and the C was £9 last week.

mtbikerboy

oh, i think i'm looking at the 2C type....and they didnt have any AA version last time i checked. are they exactly the same torch except battery size?

snotty badger

The 2C has a much tighter but brighter spot.

The 2AA torch has a better spread.

HTH

mtbikerboy

i am finding the 2C torch is good to see far ahead but not close. perhaps if i got the 2AA it could improve visibility up close. or is its spread not good enough as well?

snotty badger

I'm going to try two 2AA torches mounted on the bars and a modified 2C torch on me napper.

I figured out a way to make the spot less tight on the C torch- need to take a pic to explain though...

mtbikerboy

when you try them out, come back and post how they were. i just might adopt that setup

snotty badger

Will do.

Although I have no idea when I'll get my forks back- been nearly two weeks since I dropped them off for a warrenty repair and still no sign of them.

thurgobob

Bought two a couple of weeks ago and they are as good as any lights I've seen so far. A mate bought some £200 quid Light and motion last week and my £17.80's worth were as good. So I went and bought a third and put the three together in a sort of triangle fashion attached with 22mm plumbing pipe clips and an old handlebar clamp off a £5 jobby. I intended from the start to use a larger power supply and assumed that some sort of internal electronic gubbins was inside the alloy piece below the led so I sawed it off and you can see the small circuit board in the photo. Next off to Maplins for a LM317T voltage regulator and two 6.8 ohm resistors wired in parrallel to give 3.4 ohms or 350 m/a approx to the led for battery saving on the road with a further two 6.8 ohm resistors parrallelled with the initial two using a switch which brings the resistance to 1.7 ohms at 1.25v which will give 735m/a see picture for components, by the way just joined so how the gubbins do I post a photo.

jadamson

get a flicker account or photobucket or a photo sharing site membership(its free) and upload a pic to that then it will give you an image code starting with (bbcodes) copy and paste that link into here.

forgotrafe

I've been playing... Photos hereof my Tesco CREE monster bar light as well as my helmet light.

For the bar light, I'm pumping 14.4v into 4 of the things. Not sure if they're going to cope with that or it's all going to go horribly wrong

[/img]

thurgobob

that sounds a pain, anyhow here's a data sheet on the circuit principle just put in the correct resistors for what you need.
http://www.reuk.co.uk/Using-The-LM317T- ... ghting.htm
Make sure that the input voltage is 3v higher than the led voltage of the three crees in series 3.5v x 3 = 10.5v + 3 =13.5v min . Output voltage of the LM317T is 1.25 and the current will be fixed by the resistors. ie 1.25v/ohms =current.
I'll see how they go with 700m/a as I don't yet know the exact cree part number for the spec and max amps allowed although I am waiting for an exact answer from Cree as I sent a close up photo of the bare led for them to identify it.

Northwind

<snip!>

JK in the UK

Snotty badger - I'll be very intrigued to see you're method for widenning the beam of the 2xC torch. I've found cutting discs from a frosted A4 plastic wallet and putting them inside the casing infront of the lense SEEMS to do wonders for spreading the beam of these torches. I got the idea because most flood lenses I've seen on the net seem to be the same as spots just with a frosted kinda surface. I say seems because I've yet to test them outdoors in the dark - will report back when I do.

I've got both the AA and C torches but am keen to use the C torches. I found the C torch LED draws a greater current than the AA torches (~800mA compared to ~600mA for the AAs). The electronics appear to be slightly different and I think that much brighter spot as standard is down to more than just the lense. I also think that if making light units out of these torches the C's are much more upgradeable as there are already 3 LED units that would fit in the C heads.

Is there a reason why people are running lights in series and not parallel? It seems there must be a reason because 'proper' manufacturers seem to be doing the same thing...

snotty badger

I'll try and get a photo but basically the LED is spring loaded on the C torch so when you tighten the lens down it pushes hard againist the LED.

I pushed the LED back and placed a think O-ring in there, you'll see if you push on it- this moves the LED away from the lens griving a slighty larger spot. Not had chance to try it properly yet though.

Hope that makes sense!? :oops:

jimmypippa

JK in the UK wrote:

Snotty badger - I'll be very intrigued to see you're method for widenning the beam of the 2xC torch. I've found cutting discs from a frosted A4 plastic wallet and putting them inside the casing infront of the lense SEEMS to do wonders for spreading the beam of these torches. I got the idea because most flood lenses I've seen on the net seem to be the same as spots just with a frosted kinda surface. I say seems because I've yet to test them outdoors in the dark - will report back when I do.

I've got both the AA and C torches but am keen to use the C torches. I found the C torch LED draws a greater current than the AA torches (~800mA compared to ~600mA for the AAs). The electronics appear to be slightly different and I think that much brighter spot as standard is down to more than just the lense. I also think that if making light units out of these torches the C's are much more upgradeable as there are already 3 LED units that would fit in the C heads.

Is there a reason why people are running lights in series and not parallel? It seems there must be a reason because 'proper' manufacturers seem to be doing the same thing...

Hey, I can answer *that*.

It is to do with the difference between an LED and a filament bulb.

The simple answer is that LEDs are all slightly different due to manufacturing spread, and if several are in parallel, one that takes slightly more current at first, will heat up more, which will make it take even more current, heating it up further (compared to the rest), reducing the lifetime, and probably shorting that LED out very quickly.

In series, all the current goes through all the LEDs so this is not a problem, althugh variations within the LED might be. Variations *within* an LED will be less than *between* LEDs.

A filament bulb talkes less current as it heats up, so this doesn't happen.

Slightly more detail

A filament bulb is a bit like a resistor, so current through it increases with voltage, sort of linearly (ignoring selfheating). An LED current increases (roughly) exponentially with voltage. This means that below a certain voltage almost no current flows, and the voltage across the depletion region (where the photons are generated) doesn't rise very much above this voltage. A too-low voltage across the LED and you will get practically no light. A too high-voltage and you will get a lot of wasted voltage drop as series resistances, if you are lucky, or a shorted-out LED if you are not.

Further to this filament bulbs tend to fail open circuit, so with two bulbs in parallel, if one blows, the other should still work for a little while. In series, one fail blacks out everything (christmas tree lights).

LEDs tend to fail short-circuit, so with two bulbs in parallel if one fails, there is no light. A fail in a series LED will not [edit: of itself] make the whole chain of LEDs fail, especially if some clever current-limiting is in place.

thurgobob

In series, if for example you supply 3 x led's with a fixed 700ma current supplied using a buckpuck or simple current regulator the circuit will only draw 700ma in total and each led will receive 700ma which with a battery size of say 2500 mah gives 2500/700 = 3.57 hours,however if you wire the same three led's in parallel each will receive 700ma x 3 gives 2100ma total which will give 2500/2100 = 1.19 hours life, also if the led's are not equal then they may not all light up.

prawny

I bought 2 of these yesterday, well I thought I had but it seems as though the CREE ones have been discountinued and replaced with torces that look very similar (slightly different pacaging) but don't have CREE leds, poo!

You can definately tell the difference, the new type one gives off a greener light. According to the meter on my camera they pump out a similar amount (within a third of a stop) of light it just doesn't look quite as bright.

Still good value though.

Northwind

I'm not entirely sure if this is allowed- if not, apologies mods, please feel free to delete- but I've just listed a pair of these + handelbar clamps + batteries + charger in the for sale section, if anyone fancies getting a set for cheap with some nice goodies.

JK in the UK

Wow guys, thanks for your explanations - very comprehensive! Series it is then!

Had a go with the o-ring idea. Snotty badger - you mean within the silver metallic holder infront of the spring loaded circuit board right? Its a good idea and broadens the spot up quite nicely.

I tried my idea of cutting discs out of frosted A4 paper plastic wallets. They spread the beam nicely but you need four to get a good spread which seems to dim the light output somewhat. The o-ring and two discs seems like a good combination - will try after Christmas and report back...

Cheers

MarvintheAndroid

Georgeb : I have a couple of Opticube 510s and they don't begin to compare with the Tesco Cree for illumination at a distance. For riding in pitch darkness they are hopeless at anything above walking speed, even with a pair of them. They are very good for being seen though, and unlike the Tescos they are BS approved which is more important for road use.

About the best Cat Eyes for off road use would be the twin halogen sets with external batteries if you can still get them. At 20W total they are OK, and I have used them in pitch black both on and off road.

The Smart is primarily designed to make you visible from a distance. Don't expect to see anything. The clue is in the run time.

I now use Ay-Ups, but everybody knows that because I keep telling them !!

Marv

FrozenForest

My two Tesco CREEs are in series, powered by an Electron battery pack at 6.5V, fully charged. Here they are:




I have an MTE p7 as my main flood, and a Fenix L1D on my handlebars as an extra spot if I need it (I don't). I have taken my Cat-Eyes off - I don't need the 1.5kg of batteries weighing me down. So I don't have a single BS light on my bike (I doubt my 79p red light from Ebay is BS approved) - but then, I only ride off road.

I haven't tested my helmet lights in anger, yet, as I have a nice chesty cough to keep me fat, but in the "point them down the garden" test, they are as bright as the fenix on turbo, and are less of a spot, as they don't point in exactly the same direction.

I can't take credit for the helmet mount - that is courtesy of MarvintheAndroid, but the rest is all my own work. As I am about as good at DIY as I am at crocodile wrestling (although I can solder), that should encourage the doubters - you can do it!

My aim is to add another MTE P7 to the handlebars (they are awesome). Not that I need it, I just want to have more lumens that marv when we go out next, and see if I can at least make him cast a shadow, rather than the other way around. That will give me something to smile about, whilst I try to catch him up...

snotty badger

JK in the UK wrote:

Wow guys, thanks for your explanations - very comprehensive! Series it is then!

Had a go with the o-ring idea. Snotty badger - you mean within the silver metallic holder infront of the spring loaded circuit board right? Its a good idea and broadens the spot up quite nicely.

I tried my idea of cutting discs out of frosted A4 paper plastic wallets. They spread the beam nicely but you need four to get a good spread which seems to dim the light output somewhat. The o-ring and two discs seems like a good combination - will try after Christmas and report back...

Cheers

Yeah thats what I meant- glad you made sense of it! I still haven't tried on the bike yet though but in the point it down the garden test it seems to make a nice difference- I'll try the frosted plastic too. 8)

eyepic

Frozen forest...love the mount and appreciate that you have attributed it to MarvintheAndroid... but can you give me details of how it was made??

David