Kessil

LED Q&A thread

You should be able to run them in parallel (so that the voltage is the same and the current to the wallwart is doubled).

Has anyone used that design yet and have anything to report?
 
Parallel sounds about right Thanks! To think I used to fix helicopter weapon systems at the circuit board level in the army :(, it's only been 2 years and i already forgot how to logically read a schematic.
 
Time to start playing with attack helicopter CB's again then :p You can start by fixing mine :lol: It's grounded out back.
 
A B or C

A
DSCF1196.JPG


B
DSCF1197.JPG


C) ????


edit: after seeing the pictures it was a bit more obvious which one to do:
DSCF1202.JPG
 
Gomer said:
You should be able to run them in parallel (so that the voltage is the same and the current to the wallwart is doubled).

Has anyone used that design yet and have anything to report?
Click to expand...

+1. Also by my calculations the current in that circuit should only be a maximum of about 7 mA (when at 10V), so you could run a whole bunch of them off a single wall wart with no problem.
 
Actually, looking at it a bit more you don't even need the voltage regulator. Just get a 10v DC power supply and connect it to the two outside pins of a pot. The middle pin will have a voltage that varies between 0 and 10v based on the pot's position.

That works because a 10k pot is equivalent to two resistors in series where if the position (between 0 and 1) is x, the resistors have values 10k*x and 10k*(1-x). That operates as a voltage divider where the middle pin's voltage is proportional to position.
 
I made 2 of those regulator circuits today, one is messed up keeps filling/discharging a cap. Contemplating just hooking up my RB and my Q5 to the same reg for dimming on a fixed ratio set on via the S2 meanwell pots.

excuse the mess i just calibrated the meanwells where I had the most available outlets.


DSCF1203.JPG


DSCF1204.JPG
 
Very unimpressed with the R2 bin very yellow and not bright. I got some Q5 for a fuge light and @ 500ma they're way brighter and way whiter than the R2's at full power. Seriously considering buying 12 Q5s to replace all the R2's
 
be sure that you are using the same angle and appropriate optics. XPE/ XRE/ XPG optics are not interchangeable. The XRE has a different radiation pattern than the XPE. For an XPE and an XRE of equal lumens, the XRE will appear brighter because it has a narrower natural radiation pattern. If you were to drop 30 deg optics on both (assuming equal loss in the optics), they will be equally bright.

The color is a bin issue and not a type issue. If you want more blue, you need to get the appropriate color bin
 
Alright finally pulled the trigger, ordered me 10 Royal blues, 10 Cool Whites (XP-G), got two drivers (non-dimming) 700mA and 1050mA driver. and 40, 60 & 80 degree lenses just so I have one of each to play around with and get a feel for spread.

I wonder if I can't make them manually dimmable by running a POT in parallel with the whole string, sure I would be wasting power going through the POT, but I could adjust the dimming.. man they never had these back when I was in electronics class, wonder if current sources are in the electronics bible.
 
No? hmm like I said, back in electronics class current sources weren't really the thing. My idea was that if I could put some resistance on a string to limit the amount of current that takes that pathway vs the pathway the LEDs are on... but we always used voltage sources.
 
Hey Tony, quick question.

Could you give me a ball park figure on how many amps you think a DIY pure LED set up would pull on tank like a 33gal cube oceanic?

I live in an older town house and Ive got too many appliance and MH on one line. I'd like to convert some tanks to LED if it draws less amps so my breaker doesnt trip all the time. Given the layout and slab foundation of the house- it would cost way to much to run a new line.
 
Not Tony, but figure out how many watts you'd want divided by 120. Lets say you did a 24 LED retro thingy... each overdriven to run at 3W each.. 24 x 3 = 72W which is about 0.6 Amps. Might be a tad larger simply due to the wasted power converting AC to DC, but about a third of an amp per 12 LEDs isn't a gross over estimate or anything.
 
You know mike....you might be able to do what you want, but it will probably be pretty darn inefficient.

Marc, I have a setup with three strings of 12 LEDs run at 900 mA which would easily light up that tank.
Just some math for reference
(note, Vf is about 3.5 V)

12*3*0.9*3.5=113 watts
Figure the driver is 90% efficient
113/0.9 = 126 watts

P = I*V
so
I=P/V
I=126/110 = 1.1amps on a 110V AC line
 
Tony, yeah like I said current source.. grrr! A resistor will change the voltage, which will basically limit the resistance but what the hell does an ohmic device do if you force a particular current through it? obviously the voltage will change as a result but the voltage between two points (start and end) still would need to be the same.

OH well, I'm just going to be testing things out, dimming is for sissies :D
 
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