I wouldn't want to reduce the voltage from 24v to 6v. I meant reduce BY 6v. From 24v to 18v. The reason I ask all of this is because I want to be freed form this half blue half white lighting with only 2 dimming channels. I want to have the freedom to do a 28royal blue, 22coolwhites and 8-10 of another color, have the 3 colors be individually dim-able and running on 1 (maybe 2) power supplies. That way there's less bulk to hide. But as far as I can see, this kind of setup would be hard to do if I'm stuck with having 6/7 led's per string for ALL strings.
DIY LED driver for reef lighting
- Thread starter der_wille_zur_macht
- Start date
I wouldn't want to reduce the voltage from 24v to 6v. I meant reduce BY 6v. From 24v to 18v. The reason I ask all of this is because I want to be freed form this half blue half white lighting with only 2 dimming channels. I want to have the freedom to do a 28royal blue, 22coolwhites and 8-10 of another color, have the 3 colors be individually dim-able and running on 1 (maybe 2) power supplies. That way there's less bulk to hide. But as far as I can see, this kind of setup would be hard to do if I'm stuck with having 6/7 led's per string for ALL strings.
mprygh
New member
I just want to re-emphasize that everyone think about the power supply you plan to use
before deciding on your strategy.
The larger supplies are more efficient, cost less per watt, and have more features.
For example, I just ordered a high quality 0.99 PFC, 94% efficient MW SDR-480, 24V.
If I bought 4 smaller 120W supplies instead, it is lower efficiency, and 50% more cost.
And the usual small cheap ones have no-pfc and are in the 75% efficiency range.
For me, that difference is about 100 watts.
The downside is that with a single supply, you are unlikely to tweak the
voltage much, so that nice linear current regulator is now not nearly as great.
That said, I am doing a big system. For a small one, the tradeoff is a lot different.
before deciding on your strategy.
The larger supplies are more efficient, cost less per watt, and have more features.
For example, I just ordered a high quality 0.99 PFC, 94% efficient MW SDR-480, 24V.
If I bought 4 smaller 120W supplies instead, it is lower efficiency, and 50% more cost.
And the usual small cheap ones have no-pfc and are in the 75% efficiency range.
For me, that difference is about 100 watts.
The downside is that with a single supply, you are unlikely to tweak the
voltage much, so that nice linear current regulator is now not nearly as great.
That said, I am doing a big system. For a small one, the tradeoff is a lot different.
mprygh
New member
I can say that the regulator on the Arduino board is already toasty
when it is driven at 12V. Going to 18V only makes that worse.
The advantage of a separate supply: You can add a relay if you want,
to completely cut the main supply at night.
Or, get a cheap dc-dc converter.
I ended up buying 5V, 12V, and 24V supplies. There are various fans
and other things on the 12V. And beyond the controller, there are bus
expander, temp sensors, and other logic on 5V.
It costs a bit more up front, but lots of expandability long term.
Names Brucey
New member
OK. I would like to go ahead and order the CAT 401 triple boards but am a little confused on what exactly I need to send to Seeed. I have downloaded Seeed's eagle design rule and opened the board diagram in Eagle that DWZM did and ran the CAM job. It provides something like 12 files. Am I sending all 12 or 13 of these to Seeed? Sorry for the newb question but I have never used Eagle or any of this. Thanks.
Names Brucey
New member
Can anyone help me out with this? I know DWZM is out for a bit (best of luck through a hard time). Thanks guys.
TheFishMan65
New member
What kind of question do you have? I'll see what I can do.
I placed my order today by sending the following files to seedstudio.com:
Top layer: pcbname.GTL
Bottom layer: pcbname.GBL
Solder Stop Mask top pcbname.GTS
Solder Stop Mask bottom pcbname.GBS
Silk Top pcbname.GTO
Silk Bottom pcbname.GBO
NC Drill pcbname.TXT
This is clearly outlined in the ordering process as defined here: http://www.seeedstudio.com/wiki/index.php?title=Opensourcepcb
One item that I had trouble with since I have never used Eagle is generating the correct files. Make sure that when you process the CAM job that the resultant files are larger than 1KB. If they are all this size, then you did something wrong.
To generate the files I followed the process outlined my DWZM in post #598 in this thread, but between opening the file and starting the CAM editor I had to switch to the board by clicking FILE>Switch to board. All of my output files were empty unless I did this.
If I error'd someone more experienced with Eagle please correct me!
SpacedCowboy
New member
Another (fail-safe) way to do it is to simply send the Eagle .brd file to pcbpool.com. Eagle makes this file for you and keeps it up-to-date automatically, it defines the layout of the components on the board.
PCB-pool are pretty cheap, although they may not be *quite* as low as seesdstudio - I haven't used seeedstudio so I don't know. When I first created the CAT401 design we're all using, I used pcbpool...
If you're not confident in knowing what to do, this may be an option worth considering (no, I don't have shares in / work for pcbpool
)Simon
Names Brucey
New member
Thank you everyone. I think I got a handle on this now.
imagex
New member
I have another question i recieved my boards and must say it's alot easier to solder these then i thought when i saw the chips come in... but i a question about the 5v source... with a arduino i understand that your supposed to use the 5v out from the arduino correct?? what about if your not using the arduino?? do i just find a 5v wallwart?? or hows this work or am i understanding the whole thing wrong?? basically is the cat4101 5v is it a in or out??
cause i've seen stevesleds layout of his drivers and it states the 5v is a output and on his drivers it's bridged between the pwm and the 5v.. is that the same with the cat4101 we're doing??
also on the cat4101 chip are you supposed to solder on the the flat backside to the square??
cause i've seen stevesleds layout of his drivers and it states the 5v is a output and on his drivers it's bridged between the pwm and the 5v.. is that the same with the cat4101 we're doing??
also on the cat4101 chip are you supposed to solder on the the flat backside to the square??
Last edited:
chrisfowler99
Premium Member
Each CAT4101 board will take on PWM and use it on all the strings (1, 2 or 3) that are attached to it. And you can only drive 1, 2 or 3 strings.
So, if you want 12 strings you're going to need a minimum of 4 CAT4101 triple boards.
With is convenient because you want 4 individual pwm controls, which also means 4 CAT4101 triple boards.
TheFishMan65
New member
imageX,
CAT4101 needs 5 volts in. So you need a 5 volt regulated or other power supply. I used a 7805 off of the 24V to the CAT4101 and it gets a little warm, but works.
Yes the back side (tab) should be soldered to the ground plain for cooling.
xfifi,
For 4 PWM you may want 4 boards otherwise you may need to lift the pins from the CAT4101. Don't remember that board exactly. Also at 1000ma I would recommend a heat sink on the CAT4101. From my experimenting they run king of hot.
CAT4101 needs 5 volts in. So you need a 5 volt regulated or other power supply. I used a 7805 off of the 24V to the CAT4101 and it gets a little warm, but works.
Yes the back side (tab) should be soldered to the ground plain for cooling.
xfifi,
For 4 PWM you may want 4 boards otherwise you may need to lift the pins from the CAT4101. Don't remember that board exactly. Also at 1000ma I would recommend a heat sink on the CAT4101. From my experimenting they run king of hot.
TheFishMan65
New member
Not understanding your L1 and L1-. So W# is white string n and B# is blue string N. Correct that the CAT4101 only allows 25 volts so you need at least two string of each (W1, W2, B1, and B2). If you go with three string then each string will have an approximate voltage drop of 14 volts (3.5 per LED). This is fine if you have a 15 volt supply laying around, otherwise you are just spending extra money on 2 more CAT4101s, IMHO.
The CAT4101 can support up to 1 A. However higher current means higher loss and more heat. Let's look at the above 6 LEDs have a voltage drop of 21 volts versus 14 for 4. If the power supply is 24 volts then in once case the CAT4101 is wasting 3 watts ((24V-21V) * 1 amp) and the other 10 watts ((24v - 14v) * 1 amp). Hence the reason we would like an adjustable supply and turn it down to 21.5 volts or 14.5 volts (CAT4101 need .5v overhead).
I found (and my board is a little tight) and someone else mentioned that the CAT401 get warm. In my case I was running about 700ma and the CAT4101 where getting to hot to touch. Probably in the operating range of the device, but heat is the killer for all electronics. So I added a heat sink and now recommend them. You can always try it without and add it if needed.
The CAT4101 can support up to 1 A. However higher current means higher loss and more heat. Let's look at the above 6 LEDs have a voltage drop of 21 volts versus 14 for 4. If the power supply is 24 volts then in once case the CAT4101 is wasting 3 watts ((24V-21V) * 1 amp) and the other 10 watts ((24v - 14v) * 1 amp). Hence the reason we would like an adjustable supply and turn it down to 21.5 volts or 14.5 volts (CAT4101 need .5v overhead).
I found (and my board is a little tight) and someone else mentioned that the CAT401 get warm. In my case I was running about 700ma and the CAT4101 where getting to hot to touch. Probably in the operating range of the device, but heat is the killer for all electronics. So I added a heat sink and now recommend them. You can always try it without and add it if needed.
TheFishMan65
New member
Thanks for clearing that up for me. I hope my explanation helps you out.
chrisfowler99
Premium Member
xfifi, Ugh...I just realized my comment above was assuming you had 12 strings of LEDs, not 12 LEDs...completely disregard it. (where's an "edit" button when you need it?)
TheFishMan65
New member
Man, do I have to become bilingual to participate.
xfifi, Yes, those heat sinks should work. I think top would give better transfer, but kcress may correct me.
In French (maybe): Oui ... . ....kcress ... moi.
Hmm - maybe I better stick to English. Two years of French too many years ago just does not cut it.
I should also mention that you may get 7 XP-G off the CAT4101 (depending on current) since they are more efficient. Not sure this help since this is actually the wrong direction for the ratio of blue to white that most are going for. But maybe 7 XP-G to 12 RB would work (37:63). This may also help balance the voltage such that 2 power supplies (for .5 over LED voltage) aren't needed to keep the heat down. I am going all XR-E so I haven't done all the math, but it something I have thought about.
xfifi, Yes, those heat sinks should work. I think top would give better transfer, but kcress may correct me.
In French (maybe): Oui ... . ....kcress ... moi.
Hmm - maybe I better stick to English. Two years of French too many years ago just does not cut it.
I should also mention that you may get 7 XP-G off the CAT4101 (depending on current) since they are more efficient. Not sure this help since this is actually the wrong direction for the ratio of blue to white that most are going for. But maybe 7 XP-G to 12 RB would work (37:63). This may also help balance the voltage such that 2 power supplies (for .5 over LED voltage) aren't needed to keep the heat down. I am going all XR-E so I haven't done all the math, but it something I have thought about.
TheFishMan65
New member
Not of they are properly built power supplies.
