Did I over do it?

[Stefano]

Well... maybe, if your eyes can see below 400nm, then you may see the LED.

Not so sure about the red being IR though.

Everyone can see below 400 nm, and probably even 350 nm if the source is intense enough. I did see a 340 nm LED, filtered with 3 mm thick ZWB1, it appeared blue and there was a big focus shift between visible light and that wavelength. I had to focus my eye as if the LED was further away. I can also see the 940 nm infrared LED of remote controls in the dark, if I point it directly into my eyes. It appears red.

 

There is a difference between visible light and detectable light (let’s call it that way). Visible light is light that you can see well enough, detectable light is light that your eyes are slightly sensitive to and can be seen only in special conditions. Visible light goes about from 400 nm to 700 nm, detectable light (according to Wikipedia) can go from 310 nm up to 1050 nm.

 

The same can be said for sound. I personally can hear up to 16,250 Hz/16,500 Hz, and I am completely deaf at 17 KHz. If you search for the frequencies our ear can hear, you will find something like 16-16,000 Hz or 20-20,000 Hz. According to Wikipedia (again) in special laboratory conditions people may be able to hear from 12 Hz up to 28,000 Hz. But sound you are most sensitive to is maybe from 100 Hz to 4,000 Hz.

 

About the red/IR, the LED does emit a little bit, mainly because it self-fluoresces. The Hoya filter passes a bit of light in the 700-750 nm range, and that is still visible, even if not a lot. I have a far red LED, and I can see with it, I can use it to illuminate things up to ~2 m away for my eyes sensitivity. It appears significantly weaker than my 660 nm deep-red LED, although the output power is roughly the same.

[Akira]

It is extremely easy to make sure if a 365nm LED flashlight is on. Just direct the head toward a sheet of paper or a shirt that uses fluorescent dye. If it is on, they will fluoresce in beautiful purplish blue. Try some different ones, as some may not fluoresce.

 

My UV flashlight is TK-566 of Tank007 brand. It uses a 1W LED and was on the powerful side when I bought it some years ago. It will not be considered powerful anymore today, but it is much safer because it is driven by two AA batteries. Today, if you search for "TK-566" on eBay, the flashlights you see use are more powerful (3W) and uses a 18650 battery. So, I would rather cherish what I own.

 

Currently I use the UV flashlight only to induce UVIVF and to cure the UV resin.

[Cadmium]

The only two (or three) torches I can say much about is the Convoy S2+ with Nichia 365nm LED, and MTE 301 and 303 also both with Nichia LED's.

The specific Nichia LED's are different in each of those torches.

As far as I can tell, there is no difference between those two Gerbest Convoy 365nm item listings, other than the titles, the content of each item page look the same to me, unless you can point something out that is different.

Perhaps they just haven't edited or updated one of those pages to reflect the actual 'new' (or not) specifications of one of them.

Way back when, before i got an MTE I purchased various less expensive (then the MTE that is then) torches on eBay, not wanting to spend the $150 or more on the MTE 301 at the time.

After getting a 301, I could easily see the difference between the MTE and the other cheap torches I had spent less on. Those I have never used since, and should probably be discarded or the like.

After the Convoy came along, it won out over even the 303, just not much difference and much less expensive.

Other than they one nice feature about being able to screw/adapt a filter directly to the front of the MTE, the Convoy has it all for less $ and very compact also.

I am willing to try anything, but I tend not to 'trust' what I see and read unless someone independent has tests a few things first.

I do trust the Nichia specifications however, and anything that has a Nichia LED in it can be identified and found on the Nichia website.

Other LED's I have not worked with or tested, and I am not familiar with their credibility as much as I am with the Nichia brand and data.

 

We like to know a few things about UV torches. Just off the top of my head:

1) Peak wave length (of course). Along with that, perhaps, then band width.

2) Output of the LED.

Along with those it is handy to know the LED brand so we can look it up, reference it, see if it looks like what it is suppose to be, see if the factory LED specifications are good as claimed...

So many things can be said or claimed, you know, just to sell something...

Without testing something with a spectrometer, like JCDowdy has done with both the MTE's and the Convoy we can't really say for sure what kind of peak or range the torch LED emits.

I would like to try one of the C8's, but who knows what LED's are in it, what peak and band width they have, so far anyway.

 

Akira, Why do you like using AA more than the 18650's?

 

[colinbm]

If Steve is looking for commercial advice about these labels he should be speaking to a lawyer ?

[Cadmium]

Ulf, You seem to know more about electrical engineering than most people.

Can you break down the meaning of such as these:

"Drive upgrade for the 7135 x 3 (older drive 7135 x 2), the new Nichia lamp beads, power increases",

and,

"The built-in drive is 7135x5 single file"

 

I have not seen this before recently.

Off the top of my head is sounds like what they are saying is they are running the same LED (7135 ?) at increased power, or over driving them?

Any ideas, what are your thoughts on that?

|

[ulf]

"7135" is a constant current 350mA LED driver:

https://www.electroschematics.com/wp-content/uploads/2016/04/acm7135-datasheet.pdf

They can be connected in parallell for increased current.

It is a simple design that works well if the input voltage isn't that much higher than the LED's forward voltage.

Battery voltage = driver voltage + LED forward voltage.

 

I interpret "The built-in drive is 7135x5 single file" as 0.35A x 5 = 1.75A

If the LED has a forward voltage of 3.5V that means the supplied electrical power will be ca 6W.

 

Depending on the LED's conversion efficiency the optical power might be 2-3W at best.

[Cadmium]

Thanks Ulf!

The link David posted on the first page is the 7135 x 5, however it also says 5 watts, it says 7135*5, 1750mA single mode. Not sure what LED it uses.

https://www.ebay.com...XQAAOSwuNZeltUv

 

The ones on Gearbest say they are 7135 x 3, not sure about mA, not sure about LED now either.

The Convoy S2+ I have uses the same LED shown in the photo I posted above. The LED photos on the Gerbest page are not all the same, some of the photos there show the LED I have,

but other photos on that same item show a difference LED, which I think may be a slightly different LED, namely the Nichia NCSU276C (instead of the one I have NCSU276A).

https://www.ebay.com/itm/Convoy-S2-Grey-7135-5-365nm-5W-UV-Flashlight-Fluorescence-Pen-Torch-Lantern/383504657479?hash=item594aa8ac47:g:EXQAAOSwuNZeltUv

http://www.nichia.co...duct/uvled.html

 

So it is a little hard to say which LED is in the Convoy they currently sell, but I am guessing it is the C version.

[dabateman]

Cadmium,

The flashlight that I linked to and have now purchased, claims to use the LG LEUVA33W70RL00.

https://www.irtronix.com/leuva33w70rl00

 

Part Number LEUVA33W70RL00

Wavelength 365nm

Optical Power 1800mW

Forward Voltage 3.7V

Forward Current 1000mA

Beam Angle 130°

Rth 4.5 (Tj-s)

Size 3.4x3.4x2.37mm

 

In a month or so if it comes, I will test it to compare directly with my good convoy.

 

[Cadmium]

Thanks David.

By the way, I took one of my Convoy torches apart, and it contains two of the 7135 chips. Newer ones say they have 3 sounds like, and they sell some boards on Gearbest for the Convoy that have more...

Although I have no expertise in all that, just saying the 7135 starts to make sense now that I have taken one apart.

I ordered one of the 'newer' Convoys to find out what the differences might be.

[Cadmium]

It is extremely easy to make sure if a 365nm LED flashlight is on. Just direct the head toward a sheet of paper or a shirt that uses fluorescent dye. If it is on, they will fluoresce in beautiful purplish blue. Try some different ones, as some may not fluoresce.

 

My UV flashlight is TK-566 of Tank007 brand. It uses a 1W LED and was on the powerful side when I bought it some years ago. It will not be considered powerful anymore today, but it is much safer because it is driven by two AA batteries. Today, if you search for "TK-566" on eBay, the flashlights you see use are more powerful (3W) and uses a 18650 battery. So, I would rather cherish what I own.

 

Currently I use the UV flashlight only to induce UVIVF and to cure the UV resin.

 

Akira, Why do you like AA's instead?

[Akira]

Akira, Why do you like AA's instead?

 

I meant Ni-MH battery in AA size. Simply because I think they are much safer than the Li-Ion batteries. Ni-MH batteries are much less prone to explode!

[ulf]

It is correct that the Ni-MH batteries are safer than the Li-Ion batteries, but with quality the Li-Ion batteries in cylindrical shape like the 18650 the risk is very low.

 

Failures mainly happen if the battery has a production defect and are exposed for a mechanical trauma breaking an internal insulation barrier.

Small batteries used in drones and squeezed into place are in such a risk group.

 

Otherwise the the Li-Ion batteries with problem are mainly, if they by design has to be very thin to make a mobile phone even thinner than the last years model, not allowing enough space for the needed barrier material.

Another cause of problems is if during production foreign sharp objects happen to be included in the battery build and those penetrate the insulation barrier. That is quite unlikely for quality brands.

Explode is not really the right word. Normally during failure they short-circuit, heat up and eventually start to burn violently.

[Stefano]

Lead-acid is more forgiving than li-ion. I once forgot to limit the voltage charging a 12 V lead-acid battery, and when I noticed it it was at 16.4 V. I quickly disconnected it, I put my ear on it and I heard a lot of tiny bubbles inside, like fizzy water. After an hour or so I checked the voltage and it was I think 12.8 V. The battery still works, although it has a pretty high internal resistance. Now try to do that with li-ion...

 

If you buy protected cells, they are "idiot-proof", and you don't have to worry about anything. If handled correctly, li-ion is quite safe now.

[Cadmium]

OK, Thanks for the comments on that.

So perhaps we should discuss which batteries are the safest to purchase?

Brands, sellers, etc.?

[dabateman]

OK, Thanks for the comments on that.

So perhaps we should discuss which batteries are the safest to purchase?

Brands, sellers, etc.?

 

Actually I would like to know this.

On the flashlight forums, I have read thst the batteries actually make a significant difference with the Convoy UV flashlights.

Some Samsung battery brand was highly recommend. I have just some cheap china 18650 battery. After reading that I am curious if my bad convoy could get better with the correct or better battery.

[Stefano]

There are high capacity batteries (like the NCR18650GA, min. 3,350 mAh, up to 10 A discharge current (that’s more than 30 W)) and high drain batteries, which have a lower capacity but are capable of 20 A+ of continuous discharge current. It’s a trade-off. A Convoy uses probably ~3 W of power, so it is not necessary to use a high drain battery. I would personally buy a NCR18650GA (the battery above), as it has at least 3,350 mAh of capacity and at slow discharges it can reach almost 3,500 mAh.

 

Should we move this posts to a new topic?

[Cadmium]

This topic is fine the way it is, as far as I am concerned. Either way, a little discussion about batteries would be informative.

Brands, types, features... who to buy from, etc...?

[Cadmium]

Actually I would like to know this.

On the flashlight forums, I have read thst the batteries actually make a significant difference with the Convoy UV flashlights.

Some Samsung battery brand was highly recommend. I have just some cheap china 18650 battery. After reading that I am curious if my bad convoy could get better with the correct or better battery.

 

I have a variety, most are from eBay, so who knows about those, even about the mA ratings on them.

One set I got from the place that JCDowdy recommended, and I think those have some kind of protection?

I forget the place, but he recommended that seller, in one of the Convoy topics on here once, I think. It was a non-eBay place.

[dabateman]

Quick ebay search and those Sanyo NCR18650GA are about 20x more than I paid for my 4 pack of Chinese ones.

I will have to look up the reviews and see if worth it.

My LG convoy order hasn't been cancelled yet, but not marked shipped either. But would like to use better batteries to avoid killing the Led if possible.

 

Here is one review:

http://budgetlightforum.com/node/45975

 

This discussion is very interesting:

http://budgetlightforum.com/node/45972

[Cadmium]

John mentions the LIION place here:

https://www.ultravioletphotography.com/content/index.php/topic/2120-convoy-s2-uv-flashlight/page__view__findpost__p__15114

I think that is the place I got some from once:

https://liionwholesale.com/

[Nisei]

For flashlights, always use protected Li-ion.

Flashlights don't have circuitry inside them that shut off the device when voltage is getting low so you can ruin your battery.

Protected batteries have built in circuitry so the battery can protect itself from draining too far.

[ulf]

Actually in a single battery flashlight for UV you get a primitive deep-discharge protection without any extra protection circuits.

 

For a LED to conduct any current a minimum voltage is needed. You need to get over ca 3.0V with UV-LEDs.

In powerful flashlights like the Convoy there also needs to be a current control circuit in series with the LED, like the AMC7135 https://www.ultravio...dpost__p__35998 .

That also have a minimum forward voltage to conduct any current.

 

If you leave a Convoy S2+ on, the battery will be discharged to around 3V. If the battery then reasonably soon is charged, no harm is done to the battery.

A more important task for the protection circuit in protected batteries is to limit the maximum discharge current to a safe level, avoiding accidental overheating.

 

The risk of destroying a battery discharged to 3V comes from self-discharge. All batteries lose some of their energy, over time, due to internal current leakage.

At 3V there is not much energy left in a Lipo-cell and the self-discharge will cause the voltage to drop faster than when fully charged.

Then critically low voltages can be reached reasonably soon.

 

The handling problem with filtered Convoys is that it sometimes is difficult to tell if thy are on or off.

You have to actively look for some fluorescence. It is not as a visible flashlight that very visibly is on or off.

With the convoy, it is rather easy to leave it on not noticing.

If you come back after a few weeks, leaving the flashlight on the battery might be destroyed.

That is true both for protected and unprotected batteries.

 

The reason to still only use protected batteries, beside from the high current protection is that those types are often of a higher quality and might have less self-discharge.

[Cadmium]

Wow, Ulf, Very nice information!