310 nm Torch Conundrum [Solved: It is not working.]

[Stefano]

 

Stefano...I invented that rule of thumb in 2011 when I was working on my postdoc, and I published it on the board here along with some data in 2018? I am not sure why you are quoting me back to me! I suppose I should be flattered that you remember my posts that well.

 

I had actually decided against linking that old post because it's beyond what was needed for this discussion, but if you're going to quote me, please give credit.

Oh well, I didn't know that! I figured out the same rule myself (also looking on the internet), and with a bit of thinking (in a simplified model, LEDs work because electrons fall between 2 energy levels (bandgap) and emit a photon as a result. The electrical potential energy of an electron, which is charge*potential difference, is the same as the energy of the photon emitted. Since one electron has 1 eV of potential energy between a potential difference of 1 V, the resulting photon will have the same 1 eV energy. To drive this LED, you need 1 V). Of course I would have linked you if I knew that you already posted the same thing.

[Andy Perrin]

Stefano I don't believe you. If you can come up with a link to show that rule exists elsewhere online, please show me. I'm pretty sure I invented it. Also I gave that same explanation for it in the link above. You've done this to me repeatedly -- taken info from my posts and presented it as if you came up with it yourself. You need to stop.

[Cadmium]

Well, of course. When I say LED, I mean the LED assembly/package, similar to the Convoy S2/S2+, MTE's, and others,

they have many different LED assemblies for those depending on which model/LED you are getting, but all the other parts are interchangeable, body and battery remain the same.

Forget that idea, because I rather doubt MaxMax would sell you just the LED assemblies for that torch.

Sorry I diverged off topic.

 

Back to the point:

Andrea, take that lens out of the flashlight and see if it works then.

Here a very similar 365nm version on eBay, same body. I rather doubt this is a very good LED, not like a Nichia 365nm.

eBay item number:352958197084

Here is the assembly blowup, all the parts, body, and battery assembly should be the same as the 310nm version you have (except LED type/assembly), it shows you how to remove the lens.

Try that.

[Stefano]

Ok, so, what's happening here? This is the link I may have found (I remember I saw it when I asked myself this question): https://www.google.com/url?sa=t&source=web&rct=j&url=https://electronics.stackexchange.com/questions/396345/is-the-led-drop-voltage-difference-between-colors-linked-to-the-different-wavele/396384&ved=2ahUKEwjqrLOu0u_nAhWIgVwKHa6jBfkQFjABegQIBhAK&usg=AOvVaw0kDCE0TFTyBTJLdvDX1qnp&cshid=1582734809092. Yes, it doesn't talk about photon energy directly, but it talks about the correlation between wavelength and forward voltage.

Regarding the explanation, do you know any other one? That's probably the only one explanation you can give about this correlation between the energy of the photons emitted and the forward voltage of an LED.

And... please, tell me where else I didn't quote you saying that I came up with a certain explanation or idea. I always quoted you (at least I think, if not, please give me counterexamples), and if I didn't do that I never said that I was the person behind that idea. I remember here https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.ultravioletphotography.com/content/index.php/topic/3634-some-ideas/page__st__80&ved=2ahUKEwjhoZ_W1-_nAhVMa8AKHa7XBxQQFjAAegQIBxAB&usg=AOvVaw0KtjRd58QIb9YpTFNq3-Xk&cshid=1582736176531, page 4, I talked about a 90 GHz radiometer, and I said that I didn't remember who posted it on the forum, and then, (rightfully), you said that you were that person. I never said I found that image myself. That's the only ambiguous situation I remember.

Anyway, being the first person discovering something doesn't mean that other people can not do that after you. For example, companies developing LEDs knew that rule WAY before 2011. Does this mean that you didn't discover this fact independently? Of course not.

[Andy Perrin]

Ok, so, what's happening here? This is the link I may have found (I remember I saw it when I asked myself this question): https://www.google.c...=1582734809092. Yes, it doesn't talk about photon energy directly, but it talks about the correlation between wavelength and forward voltage.

Regarding the explanation, do you know any other one? That's probably the only one explanation you can give about this correlation between the energy of the photons emitted and the forward voltage of an LED.

And... please, tell me where else I didn't quote you saying that I came up with a certain explanation or idea. I always quoted you (at least I think, if not, please give me counterexamples), and if I didn't do that I never said that I was the person behind that idea. I remember here https://www.google.c...d=1582736176531, page 4, I talked about a 90 GHz radiometer, and I said that I didn't remember who posted it on the forum, and then, (rightfully), you said that you were that person. I never said I found that image myself. That's the only ambiguous situation I remember.

Anyway, being the first person discovering something doesn't mean that other people can not do that after you. For example, companies developing LEDs knew that rule WAY before 2011. Does this mean that you didn't discover this fact independently? Of course not.

You used my exact phrasing ("rule of thumb"). I don't for a moment think it was accidental.

[Stefano]

You used my exact phrasing ("rule of thumb"). I don't for a moment think it was accidental.

Isn't it a common english expression, like ASAP, BTW, OMG, "step up a notch", "tini tiny", etc?

 

I used "rule of thumb" because it isn't an exact rule. A 365 nm LED will not run at exactly 3.4 V, and deep UV LEDs, for example, can have very high forward voltages (like 8 or 10 V), producing only 5 eV photons (see the datasheets of Thorlabs 250 nm UVC LEDs).

[Stefano]

Anyway, you are free to believe me or not, but I didn't yet read your 2018 post, and I didn't know you used "rule of thumb" until you pointed me out that. It is crazy that you think I copied you because of a common english expression or because of a rule that isn't even that difficult to figure out (I mean, I have LEDs of 14 different wavelengths, from 365 to 946 nm, and I perfecly know that the UV ones require more than double the voltage of the IR ones. I can see that when I power them with my power supply). I still don't know where and when I posted something pretending that I had an idea which you had. If I did that (and, IF I did that, I never did it on purpose), I apologise, but, as I can remember, I always linked you, and I never disrespected you. Having said this, this is getting ridiculous.

[colinbm]

Talking about LEDs & power supplies......Yes I am aware that LEDs need to be driven at particular volts & current, that is why I am asking this question.

What is the correct procedure to setting up a LED to a power supply, is there a correct sequence....one, for a LED of known Vf & Cf, & two, for an unknown LED, Please ?

[Andrea B.]

My 310 torch is simply not working. Yes, I removed the screw-on glass "lens". I tried a a 3-battery AAA pack and also a 18650. The torch does not get warm and does not induce fluorescence in my calcite samples which are fluorescent at short, medium and long wavelength UV (254, 320, 365 nm approx.)

 

A point of failure on such a torch is often the "clickie" switch. But it is also possible that there was a faulty LEd or the wiring is goofy. I haven't had time yet to troubleshoot!

[ulf]

What is the correct procedure to setting up a LED to a power supply, is there a correct sequence....one, for a LED of known Vf & Cf, & two, for an unknown LED, Please ?

I started a new topic trying to answer that question.

The topic is rather wordy but hopefully containing useful information.

[Cadmium]

 

My 310 torch is simply not working. Yes, I removed the screw-on glass "lens". I tried a a 3-battery AAA pack and also a 18650. The torch does not get warm and does not induce fluorescence in my calcite samples which are fluorescent at short, medium and long wavelength UV (254, 320, 365 nm approx.)

 

A point of failure on such a torch is often the "clickie" switch. But it is also possible that there was a faulty LEd or the wiring is goofy. I haven't had time yet to troubleshoot!

 

Oh good, glad you removed the lens then.

Oh well... :-/

MaxMax will swap you a new one.

[colinbm]

I started a new topic trying to answer that question. The topic is rather wordy but hopefully containing useful information.

Excellent thanks Ulf.....