I am writing this in hope that it may be of help to people who looking for a decent torch out of the mass of torches on sale. It’s about torches I use or have used, and also about some modding and a home build.

I tend to divide torches into 3 groups, small pocket torches, ones slightly larger and more powerful, and the big searchlight jobs. Out of the three, the first category is in my view the most useful as they can be quite powerful for their size. I will deal with these first.

The thing about the small pocket torch is that providing it’s reasonably waterproof the torch is ideal as back up underground lighting. However, for this purpose it belongs fastened to the side of your helmet not in a pocket or worse still in a kit bag where it can be left 50 yards back.

One of the best is my Fenix E11, there is probably an updated version available now. Takes one single AA battery and gives enough light to get you out of anywhere for up to 7 hours. Use a good quality ordinary battery, not a rechargeable, or it will go flat on you.

Fenix probably make the best torches available, and they are not overpriced. I think I paid about £20 off eBay for my E11. Only issue is they do not dismantle! I have never heard of one going wrong, but if one did that would be that. Also forget upgrading.

Worth mentioning for a lot of power in a small package is this:
http://kaidomain.com/Led-Flashlights/kdlitker-flashlights/KDLITKER-C8_2-Cree-XHP35-HD-2200-Lumens-5-Mode-LED-Flashlight 
It’s a Cree XHP 35 overdriven at 1.5 amps, at least until the battery depletes. The electronics are not the sharpest tool in the box being a generic driver, but it’s a lot of power for the money. XHP 35s can be safely overdriven. Imolent do it and I have tested them exhaustively. They are one up on the XHP 50 because they are highly focusable, the XHP 50s and worse still, the 70s , are not.

Another good one is the Convoy from Fasttech.
https://www.fasttech.com/products/1601/10002364/2222907-convoy-s2-1-cree-xm-l2-u2-1a-623lm-2-group-3-5 
It has two groups, one without the silly flashes. Fasttech also supply them as a shell for a DIY build, which is what I did. I bought six.
https://www.fasttech.com/products/1618/10002463/1277401-convoy-s2-diy-edc-led-flashlight-host 

Now a lot of these pocket torches use AMC 7135 linear chips in parallel arrays, each outputs 350 mA. There is also a reverse polarity protection diode in case some chump puts the battery in the wrong way round. Problem here is that an ordinary diode has a Vf drop of about 0.7V, a Schottky diode is better as its only a drop of about 3.3V. But that’s still enough for a fresh off charge battery at 4.2 volts to only deliver 3.87V to the driver chips, obviously as the battery depletes you loose brightness and run time.

The host shells come complete but without the LED and driver. My tests have found that best beam pattern and output at lower currents its from the Cree XPG 2, which is what I fitted. My driver is just a straight 4 X 7135 chip driver with the diode removed and the contact points bridged. Its about 500 lumens output as a very nice beam for about 2 hours off a decent Li Ion cell. No modes, no signals to Mars, all it does is work. You will know when it’s going flat as it will go dim, the way torches always did.
Here are the links for the LEDs and drivers.
https://www.fasttech.com/p/1311505 
https://www.fasttech.com/p/1127404 
Get rid of the diode, it looks like an ordinary small signal. And don’t load your batteries wrong way round or it go poop.
🔗119509[linkphoto]119509[/linkphoto][/link]

A really useful cheap torch I have is a modded one of the cheap poor quality jobs off eBay like this:
https://www.ebay.co.uk/itm/XLightFire-28000LM-11-x-CREE-XM-L-T6-LED-Hunting-Flashlight-Powerful-Lamp-Torch/231978776166?ssPageName=STRK%3AMEBIDX%3AIT&var=531172300970&_trksid=p2060353.m1438.l2649 

I bought one some time ago and upgraded the driver and fitted a waterproof switch. As they come they are pretty awful. They take 4 18650 Li Ion cells in parallel and are quite bright to start with but nosedive as the batteries deplete disproportional to the amount of discharge.
🔗119507[linkphoto]119507[/linkphoto][/link]
The photo of the driver you get says it all, it’s just a control chip switching a MOSFET. I would love to identify this chip but it has no part number. I suspect it’s an illicit overproduction of a propriety brand, what you get when you move production to China.
The driver I fitted was from Fasttech and actually has an inductor, all for £4.50, but bad news is that they now all sold out. Mine was getting a bit past it with the parallel wired LEDs beginning to fade so I bought a new one and swapped the modification bits rather then mess about changing the emitters.

I had an idea for the old torch.

I also have an Imolent DX 80, I have heard of these going on eBay for as little as £160, and as such they are a bargain. But really a portable floodlight rather than a torch, they tend to spill light everywhere, but good for photography. Sold as IP 68, I trashed my battery management module due to water ingress when I was foolish enough to submerge it for only a few seconds. I could not replace the damaged chip or get a replacement module, so I had to buy a new battery pack. Bloody £90!

Anyway, I have managed to machine up a sleeve to fit the shortened DX 80 battery case to the head of the old eBay junk torch, so that was the start of my torch project.

I decided to make a 16V sealed rechargeable using technology I developed for the Scorpion X16 caplamp. I was hopeful of being able to get 4 X 20700 cells into it. I managed this but no room for the management PCB, so I ended up using the same Samsung INR 18650-30Q cells as the X16.
The head.
I cut a disk out of 16 swg (1.6mm) copper and mounted 4 Cree XHP 35s in 2 parallel arrays.
🔗119508[linkphoto]119508[/linkphoto][/link]
Now these have a Vf of about 12 volts, but a drive current of just over 1 amp, so in this case parallel is the way to go. Reflectors are as Dragon caplamp.
🔗119511[linkphoto]119511[/linkphoto][/link]
I used these drivers, albeit modded.
http://kaidomain.com/S025219-FX-3XT6-25mm-2A-5_5V-16V-4-Groups-3-to-5-Mode-Driver-Circuit-Board-for-3-x-Cree-XM-L?search=S025219 

I actually had bought a few of them for evaluation. Like a lot of Chinese components they are generic, there is a place for a second sensor resistor and components rated at 5 amps. They can be safely pushed up to 3 amps, but no more. Add a second sensor resistor of 0.18 ohms in the place provided. The reverse polarity diode can also be removed and pushes efficiency up by an amazing 22% on the lower settings. I had a few of these left lying around so used them up; I don’t use them in any of my lamps.

They have a control chip with no part number, seen this before, so was unable to get a data sheet. Evaluation therefore consisted of my lab tests which trashed a few. The ones left came in useful as they don’t have mode memory so I was able to fit two, each to one pair of parallel emitters. So output of 3 amps gives 1.5 amps to each XHP 35.

I drilled a hole in one side and fitted a 3mm red led as a low battery warning which comes on at 13 volts. It’s a LM 393 referencing a + Z13V/1KR against a + 10KR/R300
The switch is an IP 67 one I had spare which is rated at about 10 amps. It has a cover over it so it cannot be accidentally activated.

Batteries
As I have said, its 4 series 18650, high discharge. Management PCB is same as X16 and they come off charge at just over 16.7 volts. Shut down is at 10.8V.
Charging is by a 19V laptop mains adaptor charger, or an 19V inverter charger for charging off an in car 12V socket, output 19V.
🔗119510[linkphoto]119510[/linkphoto][/link]

The heart of the management PCB is an ABLIC dedicated S 8254 A battery protection integrated circuit chip whose no1 pin (Open Drain) is the FET gate connection pin for charge control. On charge this is low but goes high when charge complete, so I take an LM 393 voltage reference to compare with second reference 8MR/8MR. This charge incdicator circuit is isolated from the batteries by a Schottky diode, so can only draw power from the charger input. I have built into the tailcap a charge socket to take the laptop charger plug with a flashing red “on charge” LED and a green “charge complete” LED same as the X16 and using the electronics above described. The green is very bright and only consumes about 3 or 4 mA, a gallium nitride emitter at its best.
The reason for all this is that I have a powerful, 9200 lumen torch, which is small enough to fit into a pocket. It’s waterproof and cannot come on accidentally, unlike the Imolent which did just that and nearly set me on fire, actually burned a hole through its case.

The whole thing with its toggle switch and red cover looks so delightfully politically incorrect in these days of everything being smooth and featureless. When I bought a new computer monitor it took 5 minutes for me find the switch. Oh for the old days of car engines with gleaming manifolds and rows of SU carbs, nowadays all you see is a square block.

It’s a very practical torch, watching it charge is thing in itself, just like the X16.

The cheap eBay 4 battery torch is on the face of it a modders dream, but a project beset with problems. They came with a varying number of LEDs at slightly different prices, and outrageous output claims. But there is space for a lot of improved electronics and little else. The LEDs as they come are all parallel wired. So the 6 LEDs (actually Cree XML T6s) that would need a massive 18 amps to drive them all at full power and get just under 6000 lumens. (6 X 3 = 18).
The batteries are all parallel as I said so common sense solution is to series wire and fit a charge plug. You could use a dedicated 16.8V mains adaptor charger, but would still need to fit a charge plug and add a cell management board. So where?

I went through all this a while ago. I doubt that any of the torches on offer that use this diecast body, and there are a few, at varying prices, will actually deliver what they claim. The same goes for a lot of the funny brand names, Ultrfire etc which is free to use for anyone brand.

The Nitecore range looks very impressive but I have not worked with them. I especially like their Concept 2 which is also 4 X Cree XHP 35s. They do others with this emitter which I see as the answer to easily portable power due to the fact that this emitter is highly focusable unlike the other XHP 50 and 70 quad die emitters. The TM10K and TM28 are worth a look. Nitecore do not overdrive them, this is suggested by the output, and accounts for the small size of the Concept 2 and TM 10K. My only reservation is accidental switch on, is there a safeguard against this? I don’t know.

As far as a lot of the others are concerned, Funyfire etc, I doubt that they will deliver what they claim

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Roy, you must have far too much spare time! :)
Seriously though, great article & most generous of you to share your work like this.

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Seconded. Really useful stuff here. Thanks.

Very informative guide Roy, I've dabbled in making my own lamp in the past too, this one was 3 candlepower!

🔗83175[linkphoto]83175[/linkphoto][/link]

:lol:

Very informative guide Roy, I've dabbled in making my own lamp in the past too, this one was 3 candlepower!

🔗83175[linkphoto]83175[/linkphoto][/link]

:lol::lol:

A bit more on the no nonsense pocket torch using the Convoy host.

The host comes complete but without emitter and driver but has a spring to bear against the top of the battery which fits with a plastic clip. Forget the clip, solder the spring to the base of the driver for extra reliability.
The drivers come with different quantities of 7135 chips, each outputs 350 mA. So possibly best to use a 2 X 7135 for 700 mA as a helmet mount backup, and double the burn time, use the 4 chip for your pocket.

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Continuing my mini series

The Fellows Special described above is going very well. Light and compact enough to slip into a pocket and yet so powerful it is now my spare light of choice. The head of the cheap eBay thingy is 60mm so takes a Nitcore 60mm diffuser for photography.
Its cost about £60 to £80 to make but worth the money and the effort as I cant buy anything like it.

Moving on, the thought occurred to me that one never goes anywhere without ones keys and not having a torch at hand, I have on more than one occasion had to resort to a keyring light. Basically as many lumens as two glowworms having it off on a clover leaf!
So, wondering what was on offer as a serious but small key ring torch, I looked at the usual suspects.

Nitecore do one called the tini, outputs 380 lumens, and about the size of a Zipo lighter. But unfortunately only IP54 so in my view unsuitable for underground use. Pity, it’s a nice looking piece of kit. Other thing is that it’s a diffused beam, why? They do a slightly larger one, but has red and green lights, I didn’t want anything fangled up, I have enough of the damned flashes. looking at the Nitecore website they seem to be playing for the 'Walt' market, not my thing.

In the end I went with Imolent LD10. Has magnetic USB charging through an adaptor and as such with no open port is rated at IP68 2 metres. I believe this until I find out different. It has a range of settings up to 800 lumens and a 1200 lumen turbo mode. Its very difficult to switch on accidentally and the mandatory strobe is so well hidden, I doubt that I will ever accidentally trigger it and throw my rattle out of the pram. It’s a very well designed, well almost, straightforward piece of kit of the sort I like.
It’s so good, and I have tried it underground, there has to be catch. Yes, a big one.

Sold as a keyfob torch there is no way that you can get a keyring to go through the tiny bracket. This is frankly bloody daft and basically makes it unfit for purpose. Rather than send it back I took a bit of 1mm cooper wire ( core from household 5 amp) and after a bit of struggling with a pair of pointed pliers managed to make a ring through the tiny bracket which I then soldered. Photo below.

🔗119766[linkphoto]119766[/linkphoto][/link]

The box clearly describes the torch as a “Keyfob flashlight”, they miss out the bit about the copper wire and soldering. This can be seen in the photo.

Next job is another odd box special.
Ingredients
1 X good but plastic dome broke off, Cree XHP 35 Quad die emitter.
1 X £4 sample Ultrafire 1 X 18650 lamp body from Fasttech, bought for evaluation and then chucked to one side.
1 X old slim Ultrafire torch with switch US so thrown to one side
1 X Sample boost driver circuit from Kaidomain.

My idea was to take the driver which is a boost circuit used in the KD Litker torch previously described, and file down the circumference to try and fit it to a Convoy S2 host. Unfortunately I was unsuccessful. I then found it would fit the broken Ultrafire head, which screwed onto the new Ultrafire body being same size and thread.
See what I was trying to achieve was a slim, but very powerful torch. The KD Litker is a bit bulky in the head, as was the new Ultrafire shell. The slim torch created even has a pocket clip, and the sized down driver fitted a treat. It’s 1700 lumens and gets hot quickly, but a useful little thing all the same. You can buy this type of torch from Imolent.
Picture below shows it disassembled (on the right) and is a good guide to what torch modding entails.
On the left is the quality Convoy S2 host disassembled. The LED module is brass on this one, on the other its aluminium. I had to shorten it to make room for the driver used which is now retained by the main body rather than a little ring like seen on the left for the Convoy. This should give you some idea about building custom torches.

🔗119767[linkphoto]119767[/linkphoto][/link]

Be sure to accurately check dimensions of components before ordering. I would recommend ordering the host first and then having a good old ponder over it before you think about the other bits.
For ordinary low current use from a single Li Ion, up to 1.5 amps drive current, I recommend the Cree XPG 2 as it’s performed in my lab a tad better at lower currents than the XPL.
I now have enough torches to mount an exhibition.

That’s all for now children.

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...there has to be catch. Yes, a big one.

Sold as a keyfob torch there is no way that you can get a keyring to go through the tiny bracket.

The box clearly describes the torch as a “Keyfob flashlight”, they miss out the bit about the copper wire and soldering. This can be seen in the photo.

I tend to use this stuff, carbon fibre cord, 1mm:

https://www.amazon.co.uk/Dyneema-Rope-Cord-Black-Braided/dp/B00NHQC1FQ/ref=pd_sbs_328_img_1/258-6353529-5970018?_encoding=UTF8&pd_rd_i=B00NHQC1FQ&pd_rd_r=55641209-8d80-47c3-abd2-a74bea0ed014&pd_rd_w=dgyvw&pd_rd_wg=ipGmd&pf_rd_p=e44592b5-e56d-44c2-a4f9-dbdc09b29395&pf_rd_r=07PJC8G9XJCCHVHWF3D0&psc=1&refRID=07PJC8G9XJCCHVHWF3D0 

It will thread through, can be tied in a knot and then the ends sealed with a soldering iron. I can hang my own weight on a single thread so your keys should be safe :thumbup:

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Brilliant info Roy and a lot of the technical stuff is way over my head. But I will say I have tried lots of cheapo Chinese torches off Ebay and the thing I hated was the blue cast to the LED and the way a lot of them failed after submersing in water. I still am using my old Fenix T1 which I bought in about 2008. Its been bashed and drowned (been in the washing machine twice by accident too) and still is in great condition, and the LED is a nice white light, which is great for photographs. I would prefer to pay a lot more money and get a Fenix than buy cheaper stuff. Now I'm looking for a decent headlamp.

Great info there Roy. I notice that the Corona virus has limited some companies from supplying components until close to the end of Feb.
I guess this is to stop workers contaminating exported goods with the virus.
I'm not too bothered about this Corona virus, I drink Guinness.

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Its mainly Chinese New Year which is in February, the holiday has been extended because of the virus.

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