Looking for Higher powered UV LEDs

[sergioq]

Hello all,

Am looking for higher powered UV LEDs. Trying to make a simpler currency strip viewer. The specs for what I am using now are below****. It's a cheap LED, but it works.

My questions are:

* Are there higher powered (radiant wise) LEDs that wouldn't require a car battery to light them up?
* Do multiple LEDs mean a brighter output when it comes to UV?

Obviously there are $100 UV LEDs out there, but if there can be an $18 UV flashlight, there must be some solution to what I wish to do.

Any thoughts would be greatly appreciated as this is new to me.

Thanks ahead,

Sergio

****
ColorUV (Blacklight)Continuous Forward Current30
Forward Voltage3.5VLED Package5 mm (T-1 3/4)
Lens ColorClearMaximum Forward Voltage4V
MillicandelaN/AOperating Temperature-40~+85 °C
Peak Forward Current100mAPower Dissapation120mW
Radiant Power30mWReverse Current10µA
Reverse Voltage5VStorage Temperature-40~+100 °C
Total Power Consumption0.105 WattsTube DiameterT1-3/4
Viewing Angle15 degreeWavelength380 nm

 

[shumifan50]

You can make the LED a lot brighter by over-driving it in short bursts as used in remote controls. So instead of a current of 30ma continuous, you put 100ma through it for x% on and 100-x% off, where x will be determined by the LED's time taken to dump the heat generated. The current you can put through your example is 100ma, so leaving some headroom would be wise(80ma).

 

[Gryd3]

You can use a small array of the cheaper LEDs.

It's your choice to use a car battery or not...
When you connect them in series (daisy chaining them together) you will need a resistor for each string, and the required voltage must be higher then the voltage of all of the LEDs in the string added together. (35-40V... but only 30mA for 10 LEDs)
When you connect them in parallel (tying all the negative side together for example) you will need a resistor for each 'branch' or LED. You can keep the voltage low, but the current required will go up. (ie. 300mA for 10 LEDs, but only about 3.5-4V)
You can mix and match this method, and you will find some more resources on driving more LEDs here: https://www.electronicspoint.com/resources/got-a-question-about-driving-leds.5/

You can make the LED a lot brighter by over-driving it in short bursts as used in remote controls. So instead of a current of 30ma continuous, you put 100ma through it for x% on and 100-x% off, where x will be determined by the LED's time taken to dump the heat generated. The current you can put through your example is 100ma, so leaving some headroom would be wise(80ma).

Would this require PWM? or would you suggest something like a oneshot?
http://www.instructables.com/id/Make-an-LED-Blaster/step2/Build-the-555-ic-one-shot-timer/

 

[shumifan50]

This is essentially just a square wave with a fixed duty cycle of x%, mostly done with 555 timer. Using this trick you can get a range of more than 10m with IR leds whereas the normal range would be much less than 1m.

 

[(*steve*)]

I have a colleague making a UV LED device for exposing PCBs. He reported that with just one LED the required exposure times were comparable to his multiple fluorescent tube device, albeit with some drop off at the edges. He's planning to place 10 to 15 of these LEDs in a hexagonal pattern, and is expecting to be able to achieve quite small exposure times even through paper "negatives".

Would you like me to enquire what LEDs he's using?

 

[KJ6EAD]

http://www.nichia.co.jp/en/product/uvled.html

 

[sergioq]

Wow....all this went over my head. I feel so stupid.

 

[(*steve*)]

Heh. Don't worry. I'll find out what my colleague is using. That way we can tell if the light ouput of yours is low or if it's something else.

 

[(*steve*)]

OK, these are what my colleague bought (the 3W versions). http://www.ebay.com/itm/321340939953

He says the radiant intensity from 120mm away is similar to his 4 x UV fluro tube exposure box. The ratings are as follows:


Emitting Colour: UV
DC Forward Voltage: 3.9V - 4.5V
DC Forward Current: 700mA
Luminous Intensity: 50~55mW
Wave Length: 365nm - 370nm
Viewing Angle: 120 Degree

Note that the wide viewing angle means they will cast light over a much wider area even when you're close up to them.

You would have to use a constant current source and heatsink them. one might be sufficient for your needs.

For use a few seconds at a time, you could run it from batteries.

 

[shumifan50]

One thing to bear in mind is that looking at such a powerful UV source will damage your eyes, so the unit must be designed in a fashion such that it is not possible to look directly at the UV source or its reflection.

 

[sergioq]

My original question is here, Looking for Higher powered UV LEDs ...link is here:

https://www.electronicspoint.com/threads/looking-for-higher-powered-uv-leds.269615/

So my question is, as a total newcomer to this area, can I amplify my inexpensive UV LEDs? Do mirrors help? Do lining up 5 in a row (with proper) current make them more useful?

Yes...the ones I have help view currency threads (but dimly).

Any thoughts would be appreciated.

Many thanks again,

Sergio

 

[(*steve*)]

Yes, you will multiply your light output if you use multiple LEDs (correctly). So 2 LEDs will have twice the light output of 1. 5 will have 5 times the light output, etc.

The best options might be a higher power LED or one with a narrower half-angle. Mirrors may not make a significant difference since the light is usually concentrated in one direction already (the half-angle tells you how strong this effect is)

 

[sergioq]

I have some 5v UV LEDs that are of proper wavelength to see the currency strips in US money. Am having a problem with brightness however.

So I thought I might ask a different question?

Are there (inexpensive enough) blacklight LEDs that will view the currency strips in money (wavelength wise), yet without the harm of UV LEDS?

Many thanks ahead, as always.

Sergio

 

[(*steve*)]

It's the same question.

You need brighter LEDs, or to run them at higher current, or to reduce the ambient lighting.