Need Help with my LED project.... anyone

[jeff.reed.39]

I have a project I have been researching for some time and need to finish asap, I have various LED 5mm bulbs I will attach to a perfboard, I need to keep a constant specific light wavelength so power level is important and need something in-between the power supply and the led to do this, I have the resistor at each LED and want to know what would be a better and cheaper method to give each bulb the power it needs. I have looked at drivers but dont know if they will be specific enough to each LED I have discussed mosfet's with engineers but have not understood if they will work better but they are cheaper, and power regulators, if thats what they are called, is another possibility?

I have my total watts and amps and power etc.. worked out for each string, and I will not be connecting them all in a string but one or maybe two off the power line so if I used a driver it would power all ten LED's? or use a power regulator for every two or... LED's ...?

I will try to upload my spreadsheet so you can see the figures.

If someone wants to direct me what to be cross referencing between parts that would help immensely, I'm trying to keep it simple and not design a huge board for each bundle of LED's.

I have a digital dimmer I want to use on 4 of the strings but it requires 12v input, which would kill my LED's with its output. (**broken link removed**) so trying to find something to reduce this without causing a lot of heat....

Thank you for any help.


.............................................................................................................Total
........................viewing.......Number......................Total.........Forward......Forward.....Cont. Fwd...........Total
................Size...Angle.......LEDs used..Watts..........Watts........Volts..........Volts.........Current mA..........mA used.....mcd
380nm.......5mm..30..............10..........0.105..........1.05..........3.5............35.................30.................300
400nm.......5mm..30..............10..........0.105..........1.05..........3.5.............35................30.................300
420nm.......5mm..15..............10..........0.072..........0.72..........3.6............36.................20.................200
430nm.......5mm..20..............10..........0.114..........1.14...........3.8...........38.................30.................300...........400
440nm.......5mm..45..............10..........0.105..........0.72...........3.6...........36.................20.................200
470nm.......5mm..30..............10..........0.07............0.7.............3.5..........35.................20..................200..........2400
475nm.......5mm..15..............10..........0.114..........1.14...........3.8...........38.................30..................300..........5600
480nm.......5mm..30..............10..........0..................4...............40............25.................250
505nm.................................10..........0..................0
525nm........5mm..32..............10..........0.072..........0.72...........3.6...........36................20..................200...........7500
625nm.......3mm..30..............10...........0.042..........0.42..........2.1............21................20..................200...........5000
660nm.......5mm..30..............10...........0.057..........0.57..........1.9............19................30.................300............1300
Warm white5mm..30..............10...........0.096..........0.96..........3.2............32................30..................300...........15000
Cool white..5mm..30..............10...........0.102..........1.02...........3.4...........34................30..................300...........18000
......................................................................T= 11.26..............................................................T=3650...........55200

 

[kripacharya]

Controlling power delivered is quite unusual, and there surely are some methods to do this. But i don't have a simple reference at hand.

In the interim, what you can work with is a simple constant-current source each led chain. You can make a very simple one using a LM317 or similar regulator. This requires a single resistor (or multi-turn pot) to set the current. The resistor value would be in the range of 40 - 60 ohms for the currents you need, and main power source voltage can be around 40v.

Here is the basic setup from LM317 datasheets: (Vref is 1.25v for the LM117/ 317)

 

[jeff.reed.39]

Thank you very much for your help, I am also confused at how you can get a specific color nm out of an LED that has a varied range lets say of 465 to 475.... if the resistor is not specific, usually rounded to the next common size, and the LM317 say has a voltage output range of 1.2 to 37... I am confused at what defines the exact color (470nm) at a specific power level (3.5v,20mA) a higher or lower power supplied to the LED will change the color a small amount either way wont it?

 

[kripacharya]

LED colour does not depend of voltage/ current as far as i know. I might vary by a small amount - though i do not know for sure, but its not going to change (for example) a red into a blue.
Rather the different colours are dependant on the structure/ composition of how the LED is put together.