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There have been 156 items by Magpie (Search limited from 20-April 23)
#39235 Powerful Aquarium Lighting
Posted by
on 13 November 2012 - 02:24 AM
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#39441 Powerful Aquarium Lighting
Posted by
on 16 November 2012 - 02:02 AM
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#39224 Powerful Aquarium Lighting
Posted by
on 12 November 2012 - 11:29 PM
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#39127 Powerful Aquarium Lighting
Posted by
on 12 November 2012 - 05:42 AM
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Attached Files
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SteffNearlyFinished_fixedcutouts.zip 25.51KB
3 downloads
#38215 Powerful Aquarium Lighting
Posted by
on 30 October 2012 - 01:42 AM
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#40419 Powerful Aquarium Lighting
Posted by
on 29 November 2012 - 12:53 PM
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Second thoughts I think they are a bit low to be useful. Dont worry about them but do wire up a current limited wall wart or something.I will get some low blow fuses like you recommended 100ma or so.
Something like that , turn on with the current limit set to say 40mA and the lights dim. then wind it up checking for too much warmth in the various components.I'm going to test with the 1A 5v I have and will probably run the boards at a lower output for testing, maybe 200ma or so?
I meant power resistors to initially sub in place of the leds. Just a few 2, 5 or 10W wired up to be one or two ohms. Until you get the control circuitry and firmware correct and tested you don't want to blow the leds.This being said I will need to add a few extra resistors for testing, I guess you would recommend creating some form of regulator then for the boards especially whilst using the wall wart.
I would wait until you are happy with the boards. I still dont like the 5v and also I think I have made a layout mistake with the 5 volt tracks. I don't know how critical it will be but it isn't optimal. We should really have two separate rails for the 5v. So the noise from the leds switching doesn't upset the micro or the analogue. The analogue 5v is already separate from the micro 5v but the micro is sharing a supply with the fets and therefore will be subject to unnecessary noise. Sorry about that, It only recently occurred to me. Ideally we would supply the micro with an output from a linear regulator which is nice and clean. Have you got a cro? Anyway we will see when the boards come back.I think I am going to get a 5v 20amp switching supply eventually with build in protection as listed above, so it will give me some scope for expansion or if I really wanted to push the leds. Plus I guess the fact its switching should make it a little more efficient when running at lower output right?
This seems good enough. But you may need to beef up the transistor and lessen the resistance to give say 500mA.http://www.zen22142.zen.co.uk/Circuits/Power/add-on.html
But you will loose a volt with this the current limiting, so just for testing start with 8-12v, put the current limiter, then put a standard LM7805 (or 317 + 2 resistors) and then you project.
the current limit should be selectable so maybe switch in/out a resistor. Make on setting 30mA to limit damage on board faults. and the other one 500mA, so you can actually test you channels and firmware, without burning anything.
#40485 Powerful Aquarium Lighting
Posted by
on 30 November 2012 - 09:12 AM
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#46554 Powerful Aquarium Lighting
Posted by
on 02 March 2013 - 11:39 PM
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It's a shame I live on the other side of the planet, I am a sparky too so I could help with the wiring.
I have been scratching around for Electrical work and it has been a bit slow, but I have also been given a job reviewing somebodies embedded electrical project, It is quite interesting but I'm afraid my assessment is a bit damning. I didn't want this as I know how hard it is to finish projects let alone make them perfect. Anyway my client says don't hold back, they want the truth, and there have been more than a few failures in the field.
Hopefully this will lead into a replacement board, I want to go Arm m3 or maybe m4. 32 bit code yay. 8bit does get a bit annoying.
Node Zero, I'm not familiar with this term.
Sounds like you have big plans, you might have to resign your day job to implement them.
I made up 5 x Steff 0.4 they all work, my production techniques need refining, but each time I try a different way and learn a bit.
You have to manage it so that the solder pasted doesn't dry out before you finish placing. I think the vacuum pick up idea is good but I haven't managed to do it. RE. Mikes Electric Stuff.
All the boards work well, I have only mounted one of the version 0.4s. My lab has 3 led lights now, more than bright enough.
I added a switch to them so when they are turned off they draw just about 10uA.
#44356 Powerful Aquarium Lighting
Posted by
on 28 January 2013 - 04:28 AM
in
General Discussion
I guess you have noticed on the current limiter ps that the negative input is not connected to the negative output. Which is a bit unusual I suppose, but in this case it is correct. Remove RLoad from the circuit and replace it with your boards for testing. Your boards should have an input jumper with two wires, these connect to where the load resister was. If you are worried about polarity, don't, we should have reverse polarity protection, give it a try. If it is wrong the current limiter should kick in. If that fails then the fuse should blow. If the fuse doesn't blow and you have 5 volts on the input pins, then it will mean that you can start testing firmware. Initially you dont even need to insert the Attiny chip. However when you insert a chip make sure the power is off. As to what size wall wart you will need 9-12V dc, regulated or not wont matter. The current limiting psu should be ok with anything under 20v. Dont use a battery!!! use a wall wart 500mA to 1A is best. Batteries can really damage stuff and start fires if there is a short. A car battery is capable of 100s of amps whereas a wall wart will only give 1 or so amps. I have never built this circuit myself mind you, but I am sure it will work if you have the wiring right. While the circuit is switched on use your fingers to check for abnormal heat output from the different components, also if you hear or smell something strange then turn power off and check things.
I cant seem to get motivated to solder my own Steff4 boards yet. Maybe soon. I think I am going to do it in two steps. All the numerous hardy components first and reflow them. Then all the rest and reflow the entire board a second time. I find if you are too slow the paste dries out and isn't as sticky. Also have a quick reference board already done, so you don't spend too much time wondering which resister goes where.
I don't actually use the liquid flux, but I think it is good for difficult ICs. Did I give you a link to Mikes Electric Stuff? Hes a one man SMD factory.
#43131 Powerful Aquarium Lighting
Posted by
on 10 January 2013 - 09:22 PM
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For some reason we don't pay our VAT (10%) on items below $1000. And buying overseas is the norm for any serious purchases.
House negotiations are not going my way, out of the £11k devaluation the bank imposed, I'm currently fitting 8 of the 11
Sorry I dont understand, but then I don't know much about buying houses. I would take care as it is such a huge purchase.
Get some reflow practice on the hardier components first,
If you want a challenge try DFN with a thermal pad and no solder mask between the pads. That's what I did for the Solar charger. Each one took about 5 goes. Once you get the hang of it, it gets easier.
I must admit I found 2 soldering irons easiest for the big inductors.
#41311 Powerful Aquarium Lighting
Posted by
on 10 December 2012 - 09:49 AM
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General Discussion
I am hoping to get more electronics than software for a change.
My only beef with losing my job is the fear they gave my main project, which was software, back to the consultants who will F**K it up.
A Little software saga about my work project (not actually a quote):
Anyway that's my rant. Apart from that life is very good.Project Design done with the consultants me and one other staff member. difficult software but good design outcome. Consultants did great job here.
The project was basically an Autocad plugin that talks to a SQL database which synchronises with our CRM Server which loads data from our Quickbooks.
Data is also held in the autocad design files that get updated as changes are made in CRM or in another Windows forms app.
Sales guys request designs through CRM and are returned the PDFs of the plotted designs through CRM.
Autocad designer does risk assessment and then design to meet the assessment. Autocad releases design back to DB which synchronises back to CRM.
Sounds complicated, it was and I was hoping CRM would come to the party and it actually did. When I first heard of what we were doing I thought this project has fail written all over it, but didn't say anything as I wanted the job, and this project was why I was hired.
Then we got the consultants to tender for the project, They tendered $45000 and said they could do it in 3 months. I said it wasn't possible for me to do it in 3 months. So I couldn't compete, I would just manage them. Which isn't my strongest suit.
So they get the tender and after 6 weeks I check progress and they haven't started. 3 months and the Winforms app is sent to me but it is just a hollow shell of an app they once sold to someone else. One year later and it doesn't work and the winforms app doesn't even make sense so I don't know how to use it. the Synchronizer has the code written but not tested so obviously it has at least a month of debugging to get it going.
The CRM modifications were done, but probably only at Alpha stage.
So at that point I took the app back because they were too busy to do it anyway and in 6-12 months it finally did work and was being used. We have done about 50 designs in the last couple of months.
Stage One was finished.
I manage to throw most of there code away. Not out of spite but anything I don't understand has to go, anything that is hard to debug also has to go, such as those annoying .Net Visually designed DataSets.
So now I am on the outer, but I am hoping my project doesn't die from neglect.
The other guy I worked with on this project is an extremely good BA but a dodgy coder, but I think he can handle it, if he gets it given back.
Tell me when your boards arrive. And how they work out.
I got my boards back for a Solar mppt charger based on the Attiny861a and I was checking the current measurement, it only uses 100mOhm sense resistor and the attiny firmware control loop, it is rock solid, doesn't move a bit. That is good as your boards have the exact same control loop.
When you need some firmware I can give you the basics.
I have one chip programmed to test each channel initially. So you just plug them in and check it on the Cro see if it's all ok.
Only then put the real firmware in.
Once that is solid you can make some descisions about comms from the Netduino, and what Netduino.
#37736 Powerful Aquarium Lighting
Posted by
on 21 October 2012 - 11:09 PM
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#37418 Powerful Aquarium Lighting
Posted by
on 19 October 2012 - 08:48 AM
in
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Attached Files
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steff35v.zip 44KB
6 downloads
#32016 Powerful Aquarium Lighting
Posted by
on 14 July 2012 - 01:03 PM
in
General Discussion
I made some changes, added to new column that flags the changes.Please can you confirm that I haven't made any mistakes?
I left the inductors at 100u you can probably go smaller as well, probably down to around 10u. So many variables to choose these. 100 will be fine if you have them but say 33u might be better, but only marginally.For the 5v version, you mentioned I need a smaller inductor, can you recommend any that would be good for the job? Or will either of the ones I all ready have do the trick which seem to be 100uh and 330uh?
Look for operating voltage of 5v, but since you are providing a regulated low noise supply off board, the only thing this will do is protect against reverse polarity.You also said I need a different TVS diode, what would you recommend for this? PS I am probably going to order from Mouser in the UK.
Also bear in mind that you need to provide the regulated low noise supply off board because this is what the 12->5v part of the supply was doing.
No the sense resistor is about right, it will be ridiculously efficient but may be prone to noise.I guess the current sense will change in value right? Do you have the equation for 700ma from a 5v input?
You may want to try 200mOhms. I tried to layout my board inputs as "kelvin" inputs. Unless you do this well your current sense inputs will be prone to noise.
Any prototypes you may want to use up to 500mOhms.
Calcs: 100mOhms at around 700mA the current sense should read .7 x .1 = 0.07 volts at full load.
We are not getting all that 700ma through the sense resistor so say we get 500mA. ( Some goes through the Shottky). = 0.05v
then we multiply by 32 in the internal gain stage = 1.6 volts. our full scale may be 3.3 volts so we get a reading of 500/1024 at full current.
Your pwm outputs should feed straight in to these as long as they are 5v full scale. Dont connect the 5v but connect the rest.Finally the parts for the dimmer channels, are these already on the BOM and do the values still stand for 5v?
Apparently they are in transit.Have you recieved your boards yet and got one soldered up?
I have the parts from Digikey. The murata inductors look a mess, they must've been made by the apprentice. The last ones looked great.
I have also got some really fine prismatic diffusing glass on order, it breaks up the leds nicely. The plastic ones are good too but they look shit when they are turned off.
Good luck
Attached Files
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Steff2 BOM revised for 5v.zip 4.88KB
1 downloads
#32580 Powerful Aquarium Lighting
Posted by
on 23 July 2012 - 11:44 PM
in
General Discussion
#30125 Powerful Aquarium Lighting
Posted by
on 02 June 2012 - 11:17 PM
in
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#29304 Powerful Aquarium Lighting
Posted by
on 16 May 2012 - 11:06 PM
in
General Discussion
I haven't damaged one chip. I need more properly heatsinked leds before I can run at > 350mA.
SteffShield
The main thing with the 2uF and 4.7uf caps is that they respond fast, to do this they need minimal inline inductance.
You must use ceramic caps and you should place them as close as possible to the legs of the chip. Surface mount ceramics are even better.
Here you will have competing requirements as almost everything needs to be close.
This is the advantage of surface mount if you are going to route a board.
In order of proximity to the chip I would put
Caps, diode, inductor, sense resistor, other resistors.
the other importan thing is to work out the high current paths and put thick tracks where necessary. I think some of my power tracks are 3-4 mm wide.
You dont need to change the sense values depending on the number of leds, this is the beauty of your current driver.
You just need to be sure that you have enough voltage for the number of leds. ie. Voltage Supply > 3.1(vf) * number of leds.
As I mentioned before I would leave spots for at least 2 and preferably 3 resistors in parrallel for your current sense resistor. You could even make them switchable.
for 700mA you need R = V/I = 200/700 = 285mOhms. I found that even if your resistors are exact your current wont be so this is why it needs to be tweaked.
Also On Semi told me that you need to short pin 1 and 2 externally.
#28258 Powerful Aquarium Lighting
Posted by
on 28 April 2012 - 10:47 AM
in
General Discussion
#32606 Powerful Aquarium Lighting
Posted by
on 24 July 2012 - 10:32 AM
in
General Discussion
You can't use the FDB3502 at all! Not at 5v.
This is a N Channel normal level mosfet. I am driving this at about 11 volts on, 0 volts off.
You need an N Channel logic level mosfet. You will drive this at 5 volts on, and 0 volts off.
Get one in the same package size (DPak, D2Pak)
, with a roughly similar Gate Charge Qg ( 10-30nC) lower is better.
and a low RDS on. I marked it in yellow because it needed changing. Sorry for not making this clearer.
If you used the FDB3502s they would still work, but they wouldn't switch fully on so they would have a higher Rds.
The net result is they would run hot and waste energy.
I can't remember what you want the 1u for, it probably wont hurt. Is it C1? For decoupling the power input pins of the attiny. If it is I have used 1u ceramic.I added in the capacitor that was a 1u to my BOM
I don't follow your question. Sorry did I leave it out of the BOM I sent you? It definitely needs to be there.
Edit: Confused gate capacitance with Gate Charge
#32731 Powerful Aquarium Lighting
Posted by
on 26 July 2012 - 10:46 PM
in
General Discussion
Hi,
I have it down to 5 mosfets, which do you think would be best for the job? I have tried to fit your suggestions above:
MTD3055VLCT-ND
MTD3055VLDKR-ND
497-4335-1-ND
497-4335-6-ND
IRLR014PBF-ND
Finally will these do for the inductors? 811-1222-ND or These?
Many thanks,
Andy
I have assembled the board, I had one big mistake, one of my Black regulator transistors was around the wrong way, And I also put the wrong package on for my mosfets.
Luckily they just squeeze in.
the Black regulator is working.
I need to write the firmware to test the actual dirvers, and especially the current sense part. I should be able to get some results this weekend. Things have been a bit hectic lately.
I'll look at the Fets now.
#37401 Powerful Aquarium Lighting
Posted by
on 18 October 2012 - 10:03 PM
in
General Discussion
#32993 Powerful Aquarium Lighting
Posted by
on 02 August 2012 - 01:51 AM
in
General Discussion
Attached Files
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Steff2AS6.zip 51.7KB
1 downloads
#32978 Powerful Aquarium Lighting
Posted by
on 01 August 2012 - 01:29 PM
in
General Discussion
they seemed to be $6.00 each or was that a pack of something.Found these they seem relatively cheap and available what do you think?
Try PCE3340CT-ND I think you should be able to get something for around 50 cents, you can probably go smaller 33uF on these if you want.
from memory it is in devices and called cp1In terms of the cap symbol, which library do I need to look in?
Also you mentioned in terms of the library that I may need some files? Do you think this is the case and is this for the PCB design as opposed to the actual schematic?
more so in pcb editor, these is an excellent pdf that is built into the toolbar on pcbeditor. use that to help find footprint names
I have the channels 1 and 2 current sensing and stable.
Now I have init/boot problems and channel 3 I cannot get to current sense.
#32960 Powerful Aquarium Lighting
Posted by
on 31 July 2012 - 11:44 PM
in
General Discussion
This is just a bypass capacitor for the whole board. It's size depends on the power used by the board and the length of wire to to power supply and the power of your power supply.C21 larger electrolytic capacitor of 50uF, I have been unable to find a suitable part even in stock on digikey, am I missing something or is this a fairly heavty cap? Can you suggest any examples any where?
Anything from 10uF to 220uF would be fine, I suggest 50uF but it wont make a difference.
Also its voltage rating doesn't need any high voltage either. 16v is fine but 25v is good too. Remeber it is electrolytic not ceramic. For a computer analogy, the ceramic is like your ram and the electrolytic is like your hard drive. They are often in parrallel. It should be easy to find. The pdf schematic component is wrong is should show a curve on one of the plates and a plus sign. They are unipolar and need to be orientated correctly.
Yes that is fine.Almost there with the schematic, although I have just been changing the values of the components is this ok?
The diagram looks good otherwise,
dont worry about the DRC on those last things, you can safely ignore it.
If you really want to fix it you can edit the module and then edit the pins to be power in or whatever satisfies DRC.
Both of those are standard (12 mils x 6 mils) and (8mils x 5mils) dimensions with mils being 1 thousandth of an inch.On the topic of foot prints is there a standard for all the resistors I remember you mentioning an issue you had 0805 and 1206 I think?
Don't go any smaller than 0805 and I would use 1206 out of choice as it will be easier to measure and fix. I used 805 on the caps so I could fit them in nice and close to the ATTiny,
and 1206 on most of the resistors. When buying another thing to watch is the tolerance, but in this case it doesn't matter too much. Though it is easy to get 10% on ceramic caps and 1% on resistors so I wouldn't settle for less, incase you have spare and want to use them on another job.
After that I reckon you are done.
Now assign and/or make footprints and do the pcb layout. I find there is a fair bit of back and forth between metric and imperial while I do and check foot prints.
But I still haven't got the firmware to do the differential ADC inputs, with the 32 x Gain,
I have measured current but only as a one sided input, and because you get no gain I only get a tiny voltage.
I will try again tonight. My feeling is that it should work so it is only a matter of time.
#26779 Powerful Aquarium Lighting
Posted by
on 09 April 2012 - 02:15 PM
in
General Discussion
You just need over current protection.
This will give you
less losses
very simple circuit
excellent linearity, good for colour.
but at a cost of
fair bit of software fiddling if you change the leds per circuit, or supply voltage, if this is the case you will have to reset the max pwm
you will need fuses too, to protect your leds. make sure the fuses blow before the leds.
Have you worked out how many channels of how many leds?
Is it 32 channels of 1 led?
For the single led channels I don't think I would bother getting an inductor either.
just something like.
tlc -> PMD3001D -> nfet gate.(logic level fet, or maybe STN3NF06L)
and VCC - fuse - leds - nfet drain and nfet source to ground.
or VCC - fuse - leds - inductor - nfet drain and nfet source to ground.
| |
|--- diode --------|
Obviously prototype first.For my purposes ( domestic lighting 10 leds in series) I am going to rejig the Attiny461a, finish, improve the code, and choose the best transistors, and fet.
Maybe even go synchronous.
