Quote:
Originally Posted by
Mr btldreef http:///t/387057/going-to-try-a-led-build-any-advice-is-appreciated/120#post_3435945
thanks a million... i thought i picked the right one. one more question...
i have to find the resistance value.... hovv?
i place resistor on main povver to the strings?
or on each string?
also i had seen a post on the big site... about protecting the dimming device.... my audrino controller. once again use a resistor???
The simple route would be to just use what every body else is using in this case. 1ohm-5watt resistors at the head/front of each string, with 1 amps fuses being ran in front of those.
Calculating resistance value for resistors isn't needed in a case like this where you are using led specific types of drivers since they only supply the amount of voltage that the load/leds require in order to operate. As apposed to other types of power supplies that put out a constant voltage. These put out a constant current and the voltage is adjusted by the driver automatically. The 1ohm-5watt resistors in this case, or like in Lois's case are used for nothing more than a convenient way to test voltage which easily allows us to convert as a measurement of current. A little bit different than measuring current how folks are typically using the ELN's. The fuses are what protect the strings. Because if 1 string goes out from a bad led then all of the remaining current gets passed through the other strings. So the 1 amps fast blow fuses are employed to blow incase current exceeds 1 amp in order to protect all the other strings.
Honestly, I'm not 100% sure for the dimming device. I haven't seen anyone using anything to protect the micro controllers, but to be honest I haven't really followed the audrino threads too much. I'm sure there's a way but I'll have to do a little more research on that and look at my notes. The resistance calculations are confusing so I have to have all of the info in front of me to make sense of it all. My guess is folks must be using it to protect from over voltage. But I'm also thinking those folks may be running different power supplies than the meanwells if they're doing that.