DIY LEDs - The write-up

[akindbro4u]

I have to do it - just becuase of his tone - sorry


Seems like he has tried quite a bit of CREE for someone that doesn't use them.

He is also on the candle power forums saying how the leds he "likes" so much will melt plastic from several inches away. Back to my point on thermal management. And you too were been very kind. Three posts and not a good thing to say.

Stu,

Where are you getting your information. I am not diesagreeing, but how do you know he needs a separate 10 volt supply? For $160 dollars this board must be more just a PWM. Or maybe I found the wrong one at cutter.

I couldn't find one at cutter. It appears to be an inline pwm for a non dimable wm, to make it dimable however.

 

[Jay1982]

Yeah the lights are coming on at all. I just tried to plug it in the first way I had it where the lights were on full blast. I did something to it and it fried the lights or the driver. I'm about to try using a different driver to see if its the lights or the driver.

 

[TheFishMan65]

I read it wrong. The whole thing is $164; this is about a $30 option.
Cutter Site

 

[akindbro4u]

like this for a 9 volt

 

[Jay1982]

Thanks Stu!! It works! THANK THE LORD IT WORKS! lol, wow! Ok this feels great. The multimeter read .801. I turned it down to .751 and I'll run it there.

Seriously you guys have been great with me and super paitent! Major props goes out to all of you!

 

[akindbro4u]

I read it wrong. The whole thing is $164; this is about a $30 option.
Cutter Site

the driver in the kit is non dimmable, so they must be adding pwm inline.

 

[akindbro4u]

Thanks Stu!! It works! THANK THE LORD IT WORKS! lol, wow! Ok this feels great. The multimeter read .801. I turned it down to .751 and I'll run it there.

Seriously you guys have been great with me and super paitent! Major props goes out to all of you!

just remember that a nine volt is only 90% of what the driver expects. so go a little lower if you plan to add 10v pwm later.

 

[Jay1982]

Will do! Thanks

 

[TheFishMan65]

If the driver is not dimmable then maybe Jay had it hooked up correctly. Sure wish I could find a data sheet.

Jay,

Are you turning down the current before hooking it up. You had two string if you pu 1.3 amps through one well I got bad news.

 

[stugray]

"the driver in the kit is non dimmable, so they must be adding pwm inline. "

If you are using a standard power supply (voltage controlled), then dimming after the supply is fine, like using the PWM.
This is exactly how I use a Micro-controller with PWM & a Power Mosfet to control current.

However, If you try to use a Constant Current (CC) supply with an In-Line PWM you are seriously messing with the Drivers control system and yanking it around.
Some CC supplies use PWM themselves with a feedback circuit to try to adjust to to target current.

If you then install a PWM circuit downstream, you are removing the load and putting it back very fast.
This messes with the CC driver & you dont know what it will do.

Stu

 

[akindbro4u]

"the driver in the kit is non dimmable, so they must be adding pwm inline. "

If you are using a standard power supply (voltage controlled), then dimming after the supply is fine, like using the PWM.
This is exactly how I use a Micro-controller with PWM & a Power Mosfet to control current.

However, If you try to use a Constant Current (CC) supply with an In-Line PWM you are seriously messing with the Drivers control system and yanking it around.
Some CC supplies use PWM themselves with a feedback circuit to try to adjust to to target current.

If you then install a PWM circuit downstream, you are removing the load and putting it back very fast.
This messes with the CC driver & you dont know what it will do.

Stu

the driver they sell in there kit uses a pwm loop, so I am not sure what this part is for, or where it goes. typical cutter conundrum.

 

[HeneryH]

FYI - many of us have noted that the Cree XPE has a much steeper Vf/If curve. We all thought the XPE was much more sensitive. Just realized that it is an optical/graphical illusion as the axis values are not the same on the two graphs. Once normalized, the curves are remarkably similar.

 

[CJO]

What size screws does everyone use to fasten their LEDs? The smalles stainless steel self-tapping screws that I've been able to find locally are #4x1/2", which seem too big (though I didn't have an LED with me to compare).

Thanks,
CJ

 

[TheFishMan65]

I use a#4 with a nylon washer. I have read that a lot of people do that. I also did not bother with self tapping. I think with self tapping you have to replace the screw if you take it out. The problem is that you don't want to tap the same hole twice. I just used regular screws, but don't tap 2 holes with one screw (they break - go ahead and as me how I know ). Don't know a lot about self tapping and not , but I thought I would give you more to think about, and if I bring it up we will get answer before tomorrow

 

[CJO]

I use a#4 with a nylon washer. I have read that a lot of people do that. I also did not bother with self tapping. I think with self tapping you have to replace the screw if you take it out. The problem is that you don't want to tap the same hole twice. I just used regular screws, but don't tap 2 holes with one screw (they break - go ahead and as me how I know ). Don't know a lot about self tapping and not , but I thought I would give you more to think about, and if I bring it up we will get answer before tomorrow

That's great news. It certainly makes it easier for me to source the parts. Do you remember what size drill bit you used to predrill the holes?

Thanks,
CJ

 

[stugray]

I use nylon 8-32 nylon screws and a nylon washer.
The screw does not have to fit INSIDE the slot on the stars, it just has to clamp down.
I tighten them just enough that you see the head angle over a bit.

The drill is a #29 and I tap all of my holes with a battery powered screw gun.
Just dont clamp it too tight in the chuck so that it will slip & not break if it binds.

I also clean the tap with a wire brush & put a drop of oil on it for every hole.

I also make a tapping jig to keep them all straight.

Stu

 

[TheFishMan65]

For the #4 screws the tapping chart calls for a #43. I am pretty sure I used a 3/32. I think that the #43 is .089 inches and the 3/32 is .0938. Having looked all that ip and looking at the numbers if you do use the #43 then you may want to tap. As I keep mentioning at 3/32 the screw is only good for one tap. Vice grips are your friends.

 

[wfournier]

I use nylon 8-3/2 nylon screws and a nylon washer.

FYI that should be 8-32.

 

[The Grim Reefer]

OK, did a temp test after leaving the unit on a couple hours. I am getting 110F on the side of the star measuring inside one of the cut outs so it's closer to the LED, I get 105 or so on the back side of the heat sink. How does this translate as far as die temp of the LED?

 

[JoshuaG]

After running straight LED's for almost a year, on my new tank I'm going to mix them up with T5's. I have a IceCap 4 bulb T5 retro, I'm thinking of adding 3 LED's strips using the aluminum channel stock. So it would be a T5 bulb, LED strip, T5 etc. Similar to the new IceCap Reef Illumination fixtures.

My question is, what would you guys suggest as to # of LED's per strip? I was thinking 13. My tank is 48x30x20, that would give me 39 LED's and 4 T5's for total lighting, I think that would be plenty for whatever I want to keep.

My only concern is 13 LED's stretched over about 46" might not blend very well. Any thoughts? I would be using Cree XR-E's.