Calling all EE's please

[DarinSchmidt]

lol, makes sense, i never thought of it that way. Thanks cyber

[DarinSchmidt]

Ok, i'm going to scratch the PWM for now as i dont feel like messing with it at the moment and will be wanting to incorporate an Andruino for that. So for now i just want to do some manual adjusting with some POTs.

I was looking up a LM317A and I'm assuming that this will do the trick to limit the current. Just dont know how i would connect it though. I connect the 48vdc to the in, out to the negative of the psu and the POT to the ADJ peg??? If thats correct, how exactly does this work? as in, do i connect the 48vdc + to the POT then to the ADJ peg or what? Its kind of late and my brain is ready for bed...

Trying to make a cheap manual control constant current device to hold me over till i am ready to dive into an Andruino later this summer.

[cyberwollf]

http://diyaudioprojects.com/Technical/Voltage-Regulator/
2nd project down shows you how to connect and calculate the R values.

Whats max Vin on 317?

[cyberwollf]

even better

http://www.reuk.co.uk/Using-The-LM317T-With-LED-Lighting.htm

And you'll want a big heatsink.  Also, whats the max Watt draw.  48V at 700mA is 33 watts. 

[DarinSchmidt]

not sure what the Vin is, i dont see it on here. but here is the datasheet for it http://www.national.com/ds/LM/LM117.pdf I'd like tfor the max draw to be 48 watts just to be on the safe side if i want to run them at 1A, but i doubt that i want to.

[DarinSchmidt]

well it seems that chip can only handle 40v, i may need to go with something a little more powerful since it also cant provide me the 50w needed.

this looks suitable, but is it saying that it can only handle an 80v input or up to an 80v input? http://www.national.com/ds/LM/LM4732.pdf

[DarinSchmidt]

nm, overlooked where it said supply voltage is 20-80v. I think this is the chip that i'm going to use so that i can still keep the amount of LEDs per array that i have since i only have 5A to work with.