DIY LED driver for reef lighting

here is my design. Sorry the soldering is a bit sloppy as I did it by hand with some solder paste and hot air reworks station. Next time i will deff get a stencil made and it will be much neater. Bascially there are 2 circuits one runs at 700ma and the other at 800. If anyone is interested i can give you more details on my the specs and such. I calculated everything myself by hand though, I didnt just plug and play stuff.

<img src="http://img204.imageshack.us/img204/386/p1010019vc.jpg" alt="Image Hosted by ImageShack.us"/><br/>By <a target="_new" href="http://profile.imageshack.us/user/mdd1986">mdd1986</a> at 2010-05-17
 
Not sure what is going on CAT4101 on mouser are $3.46 on digikey $3.46 and at Future $1.54. Prices may have gone up and future just hasn't reordered recently.
 
Seeed PCB

Seeed PCB

Got my PCBs today, for anyone keeping score:

Ordered on 4/26
Processing email 4/27
Order Shipped email 5/5
Foreign Acceptance, May 08, 2010, 12:40 pm, HONG KONG
Foreign International Dispatch, May 15, 2010, 11:19 am, HONG KONG AIR MAIL CENTRE, HONG KONG
May 19, 2010, 11:47 am, CHICAGO, IL 60701
May 21, 2010, 2:42 am, GAITHERSBURG, MD 20898
Delivered May 22

They sent 12 boards, 2 extra and they look good.

Got to thank der and everyone else on this thread for all the help and info.
 
Kcress..wooo you are up and early on Sunday ;) Got my new PCB coming on 15th May 2010, each PCB is 140mm x 240mm which will have enough space for 6 onboard drivers plus enough space for 10 x Cree XP-G and 20 x Cree XP-E LEDs with 10mm Carclo optics.
 
tahiriqbal said:
Kcress..wooo you are up and early on Sunday ;) Got my new PCB coming on 15th May 2010, each PCB is 140mm x 240mm which will have enough space for 6 onboard drivers plus enough space for 10 x Cree XP-G and 20 x Cree XP-E LEDs with 10mm Carclo optics.
Click to expand...

:beer: Going to bed now.. 3:15AM

Sounds nice! Hope to see a picture of the board.. Not the same as your last one?
 
;) Good night Sir.. No, not the same as the last ones as they had only space for 10 LEDs. New and improved PCB board with added features is to come very soon.... I am still working on simple soloution for the housing around the LED fixture. My heatsink is quite a large one as you have seen in the past ;)
 
kcress said:
WOW, a full month.. Ouch. What were the dimensions?
Click to expand...

Yep, and I am not a very patient. They advertise the service as 10-30 days. The boards are 50cm square, that is Seeed's $20 service, so you cant beat the price $23.52 shipped for 10 small boards, and they shipped 12.

I found a cheap laminator which looks like it will help out my toner transfer process, I am going to do some additional parts that way, but I think I will use Seeed again, and learn to wait.
 
I soldered up a bunch of the dwizum CAT4101 boards a while ago and had briefly tested one with a test setup of LEDs I had previously used with a buckpuck. I finally got around to a 'real' setup and made some measurements. The driver board works fine, and I had almost no heat on the CAT4101 chips (even without tuning the the 24 input supply). I soldered up a 555 PWM circuit (design from the internet) to dim because my hydra isn't finished yet, and after making some spots in my eyes while playing with it, I measured the milliamps and got only 590 at max. I know the PWM circuit I built only has a maximum of 95%, but this seems low.

What is the expected max current for this board? (I know it is probably in this thread somewhere but I can't seem to find it). I am wondering if my cheapo Micronta DMM is just reading low, but it seems like very low if the design for this board was 750ma or so.

So then I tried putting a 1 ohm resistor in series and measuring the millivolts across that, and it gave approx the same, 580mv (but I don't know how close to 1 ohm the resistor really is).
 
tahiriqbal,

"Got my new PCB coming on 15th May 2010, each PCB is 140mm x 240mm which will have enough space for 6 onboard drivers plus enough space for 10 x Cree XP-G and 20 x Cree XP-E LEDs with 10mm Carclo optics. "

Is this a Metal core PCB with the drivers & LED mounts included?


That is what I have been thinking, but havent found a MCPCB house that is reasonable until recently.

Stu
 
stugray said:
tahiriqbal,

"Got my new PCB coming on 15th May 2010, each PCB is 140mm x 240mm which will have enough space for 6 onboard drivers plus enough space for 10 x Cree XP-G and 20 x Cree XP-E LEDs with 10mm Carclo optics. "

Is this a Metal core PCB with the drivers & LED mounts included?


That is what I have been thinking, but havent found a MCPCB house that is reasonable until recently.

Stu
Click to expand...

Yes it is Stu.....

We have been using local MCPCB house which is quite good with lead turn around time and very flexiable on any quantities orderd too. Then again we give them very regular business on our other product range ;)
 
OK, we should be getting 700ma with the 768 ohm resistor. So my meter is off by 16%....bummer. It seems to work fine with DC sources like batteries, but I am guessing the PWM waveform is screwing it up. Time to get a decent meter. Any recommendations for meters that won't break the bank?
 
Obi-dad,

Can you take out the PWM temporarily? Maybe it is not truly at 100%. Maybe it is running at 86%. You said the PWM runs at a max 95%. So 95% of 700 is 665. 580 over 665 is 87%. Look I gained you a % point :). I thought your math was wrong (looks good to me), but I will leave my calculation here in case any one cares.

I would stll try taking out the PWM. That will at least verify the meters. Also measure the resistance between the pin (I think 2) and ground. If there is a bad solder joint it could add some resistance and therefore decrease the current.
 
Obi-dad said:
OK, we should be getting 700ma with the 768 ohm resistor. So my meter is off by 16%....bummer. It seems to work fine with DC sources like batteries, but I am guessing the PWM waveform is screwing it up. Time to get a decent meter. Any recommendations for meters that won't break the bank?
Click to expand...

Cheap meters use very simple electronics and then make assumptions.. These assumptions are fine for simple applications but fail majorly in many less common situations. Note the recent wattmeter thread. Any meter that professes to be a "True RMS" meter, or something similar will work as expected. They make no assumptions and will show the correct voltages and currents in any but the most esoteric circumstances.
 
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