I need help powering and switching 4 types of high power LEDs

Thread Starter

bjz

Joined Nov 13, 2017
4
I hope I can find some help here. My electronics knowledge is basic and a little rusty, but soldering is no problem, at least that helps ;-)

I want to build something but I have no experience with high power LEDs so I have no idea how I should do it the right way.
So, let me explain.

I want to make a lightbox with 4 different colors of LEDs: blue, green, yellow and white. I will only use one color at a time and want to be able to switch instantly from one color to the next. I have 4 LEDs from each color, which are:

- Osram Oslon SSL darkblue (700mA, 3V, 1W)
- Osram Oslon SSL green (350mA, 3V, 4W)
- Osram Oslon SSL yellow (350mA, 2V, 3W)
- Nichia NVSW219B-V1 white (700mA, 3V, 5W)

I have a heat-sink and a power adapter (where I can choose 3, 5, 6, 9, 12V). I thought I could use this with some resistors to power the LEDs, but I read on internet it might not be that easy, that's where I got a bit lost. The only thing in found out that it would be better/easier to use a constant current source.
So, I found one, but then I read I cannot switch instantly from one color to the next because of the capacitor in a constant current source.
Now I'm really lost and could use some help with this. I don't really have the time to read into all the electronics theory especially because this is a one time project.
 

alfonsoM

Joined Nov 8, 2017
41
Since You have a large capacitor on the output of your power adapter you don't need a large capacitor on the input of the current source. Remove the large capacitor from the input of the current source so you can switch it fast.
 

GopherT

Joined Nov 23, 2012
8,012
I hope I can find some help here. My electronics knowledge is basic and a little rusty, but soldering is no problem, at least that helps ;-)

I want to build something but I have no experience with high power LEDs so I have no idea how I should do it the right way.
So, let me explain.

I want to make a lightbox with 4 different colors of LEDs: blue, green, yellow and white. I will only use one color at a time and want to be able to switch instantly from one color to the next. I have 4 LEDs from each color, which are:

- Osram Oslon SSL darkblue (700mA, 3V, 1W)
- Osram Oslon SSL green (350mA, 3V, 4W)
- Osram Oslon SSL yellow (350mA, 2V, 3W)
- Nichia NVSW219B-V1 white (700mA, 3V, 5W)

I have a heat-sink and a power adapter (where I can choose 3, 5, 6, 9, 12V). I thought I could use this with some resistors to power the LEDs, but I read on internet it might not be that easy, that's where I got a bit lost. The only thing in found out that it would be better/easier to use a constant current source.
So, I found one, but then I read I cannot switch instantly from one color to the next because of the capacitor in a constant current source.
Now I'm really lost and could use some help with this. I don't really have the time to read into all the electronics theory especially because this is a one time project.

How will the switching be initiated? A selector switch (4position? -easiest) or four individual push buttons (more difficult), sensors (more difficult) telekinesis (most difficult for me but may be very easy for Harry Potter), hope (easiest but unlikely it will work).
 

Thread Starter

bjz

Joined Nov 13, 2017
4
Hi Douglas Silva and Gopher T.
Indeed, I want to use a 4 position switch as this seems to me the easiest solution, but as I said, I got a bit lost and it's already more difficult then I thought (otherwise I wouldn't have posted here ;)
 

GopherT

Joined Nov 23, 2012
8,012
Hi Douglas Silva and Gopher T.
Indeed, I want to use a 4 position switch as this seems to me the easiest solution, but as I said, I got a bit lost and it's already more difficult then I thought (otherwise I wouldn't have posted here ;)
That is why we are here.

Which constant current source are you using?

Is your 3, 6, 9 volt adapter capable of supplying 700 mA?
 

Thread Starter

bjz

Joined Nov 13, 2017
4
I currently don't have a constant current source. I thought I could only use the power adaptor. Then I discovered I might need a constant current source, from there I don't reall know what to do anymore.
It's a Voltcraft SNG-1000-OC with an output current of 1000mA.
 

GopherT

Joined Nov 23, 2012
8,012
Here is the concept I would use, forget the constant current stuff. You are unlikely to have a catastrophic failure and you are not powering with lithium batteries.

Adjust the low value resistors using ohms law to get the brightness you want.

Buy 4 each of

2.2 ohm @ 5 watt or more
3.3 ohm @ 2 watt or more
4.7 ohm @ 2 watts or more
6.8 ohm @ 2 watts or more
10 at 1 watt or more
15 ohms at 0.5 watts or more

Adjust brightness as needed.

D2428E29-4237-4D4E-9AA2-F2FE465B95B6.png
 

Thread Starter

bjz

Joined Nov 13, 2017
4
Sorry for not replying earlier, some urgent personal matter kept me busy.
I just want to thank you for the help, I got it working !
 
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