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### Author Topic: Driver for constant current that I am developing.. Work?  (Read 17149 times)

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#### matheuslps

• Guest
##### Re: Driver for constant current that I am developing.. Work?
« Reply #15 on: March 31, 2011, 07:45:13 AM »
So, I went to the laboratory at the college and made some practical tests....

OBS: I will put only image links because it is easy to see.....

Well, I am very happy with the results.

First I took one led and connected it to the power suply and rised the voltage. It did not work very well, the led was bllinking.... So I changed the aproach and I made a current power suply. Just put the voltageĀ“s knob at maximum and I increaded the current slowly....

First, see my power suply:

http://i.imgur.com/Ugh7W.jpg

I put a fan below the heatsink. This power suply has two power, on the left I powered the fan, 11.6~12V:

http://i.imgur.com/qcJT0.jpg

Here you can see the first test, 3V@560mA

http://i.imgur.com/lYtLg.jpg

Here is 3.1V@740mA. The image shows 3.0V, but the power suply change very quickly to 3.1V:

3.2V@990mA:

http://i.imgur.com/6tSXh.jpg

3.3V@1.60A:

http://i.imgur.com/5cuhE.jpg

3.4V@2.04A:

http://i.imgur.com/uuDAk.jpg

3.5V@2.45A:

http://i.imgur.com/Huzc2.jpg

And finally, 3.6V@2.8A. Sure I can go higher, but the datasheet says that this is the maximum current..

http://i.imgur.com/M9WI3.jpg

This is a image of all 3 leds on the same heatsink:

http://i.imgur.com/eT1f6.jpg

The circuit:

http://i.imgur.com/sdOm6.jpg

Now I started the test with the 3 leds in serie. Just turn on the power supply and aplied some current. 8.2V@150mA

http://i.imgur.com/ruZKe.jpg

The circuit:

http://i.imgur.com/3Hhmd.jpg

8.9V@490mA:

http://i.imgur.com/LoCB6.jpg

9.9V@1.5A:

http://i.imgur.com/qC8rn.jpg

The circuit:

http://i.imgur.com/0dq62.jpg

10.3V@2A:

http://i.imgur.com/roNcx.jpg

10.7V@2.8A

http://i.imgur.com/1ma2h.jpg

The circuit:

http://i.imgur.com/lrxnj.jpg

Lets try to make light on all of the room:

http://i.imgur.com/nSOWS.jpg

The system:

http://i.imgur.com/LPZfE.jpg

Ahhh, my notes:

http://i.imgur.com/KX71t.jpg

All 3 Leds@2.8A. The guy in red is the one who cares of the laboratory, the midle one is my electronic teacher and the right one is my electric protection teacher:

http://i.imgur.com/NYM60.jpg

Just one more:

http://i.imgur.com/gpNIY.jpg

So guys, I am very happy with this first result. I think that this leds needs a lense to narrow the light beam.

What do you think?

bye

« Last Edit: March 31, 2011, 08:52:40 AM by MatheusLPS »

#### kam

• Hero Member
• Posts: 1849
##### Re: Driver for constant current that I am developing.. Work?
« Reply #16 on: March 31, 2011, 23:10:11 PM »
you are so cool! And i think that the LEDs are super powerful. A lens is indeed a great accessory for those. Tell me something, i see you have a fan on the heatsink. Does it get TOO hot and you need a fan? i mean, if i use similar leds for room light (not main light but something for watching tv), i need to consider a fan as well?

#### matheuslps

• Guest
##### Re: Driver for constant current that I am developing.. Work?
« Reply #17 on: April 01, 2011, 02:22:27 AM »
Hum...

The fan was just to test those leds. I did not know how much they could get hot.

With the fan the heatsink became a little warm. I forgot to test without the fan.

But to not have problem, use a bigger heatsink.

There is a book on the college with some calcs to choose the right heatsink. I will take it and read.

bye