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There have been 156 items by Magpie (Search limited from 09-May 23)
#38363 Powerful Aquarium Lighting
Posted by Magpie on 01 November 2012 - 11:56 PM in General Discussion
#38421 Powerful Aquarium Lighting
Posted by Magpie on 03 November 2012 - 11:47 AM in General Discussion
But if you just put a tiny square of insulator underneath, you can solder on both legs any way. It's a bit of a bodge but will work if the footprint is wrong.
Just going to few about 12 house now, what a Saturday! But I will make the amends and catch up later.
Does that mean you've been drinking for 12 hours? Don't fall in the aquarium, I am picturing some sort of James Bond evil villain type of aquarium.
what those atlas guys say about remote monitoring, is so true.
#38267 Powerful Aquarium Lighting
Posted by Magpie on 30 October 2012 - 11:41 PM in General Discussion
It is hard not to make a mistake on a board. You will definitely see improvements you will want.I added some drill holes, I will probably relay the board slightly once I have tested one working.
the Gerber lines up properly, I don't know about the .pho file.
Just make sure the foot prints of the stuff you order matches the ones on your board.
In steff2 I ordered D2Pak fets but had footprints for DPak fets luckily this mistake wasn't critical as I could force them on.
If you want to use Seeed Studio then I would scrape off approximately 1.1mm of the height of your board. It will save you money.
If you use someone else it may not matter.
Height : 30.4 -> 82.5 = 51.1mm
Width: 123.2 -> 261.6 = 138.4mm
Seeed Studio use 50mm increments for pricing.
In kicad there is a yellow pcb edge layer, right click on the lines and edit the y value to make it 50mm long.
Follow the instructions from Seeed Studio to the letter, for you first spin use green it is cheaper.
If you cut the board down to 50mm x 138mm then you can buy the 5cm x 15cm option from seeed.
PCB Cart is another place.
But I think UK has a lot of manufacturers too.
#35299 Powerful Aquarium Lighting
Posted by Magpie on 15 September 2012 - 01:12 PM in General Discussion
#34664 Powerful Aquarium Lighting
Posted by Magpie on 04 September 2012 - 11:18 PM in General Discussion
#39668 Powerful Aquarium Lighting
Posted by Magpie on 19 November 2012 - 10:40 PM in General Discussion
#39770 Powerful Aquarium Lighting
Posted by Magpie on 20 November 2012 - 10:39 PM in General Discussion
8mm ? 8mil big difference. Very confusing, if only the world would go metric.
I choose 6mil because it didn't cost any more. but I don't think you have anything will a very small pin pitch so it wont matter.
I just used a chip that was a DFN (QDFN) package. Then it starts to matter. 50mil between pins. unlike the dip which has 254 mil.
the fuse holders I used are from futurlec
futurlec fuses
the picture at the top with two separate holders. I cant remember if we used m205 (5mm) or 3AG(6.3mm) but obviously you need to get the ones that fit the footprints. Check the length of the mechanical outline, it will say what fuse size we used.
update: I checked my steff2 boards and they have m205 ( 20mm x 5mm) so I think you have the same.
I used no lense yet, it is actually what I am having the most trouble with. the leds can be very dazzling and they need some diffuser. The board doesn't need heatsinking but the leds probably do. I just riveted them onto aluminium. I didn't even use heat compound as it is too messy. I tend to run everything fairly cool (<500mA) so they almost get away with just the mcpcb.
Yes the pots will be good.
remember for testing you need a current limited supply.
You can make a current limiter with a pot on vero board. and maybe just use a wall wart.
something like this.
My link
Or maybe start with some very low fuses and if you see a bit of light on the leds then move in bigger fuses.
You will also need some code , which I must have posted before, that you need to adjust and upload. You will need AVR Studio 6 which integrates somehow with Visual Studio.
And a programmer board. to program the chips. I have an AVR dragon but I think a Bus Pirate would do the job, it also might be useful for your SPI, I2C stuff.
You can probably also use a netduino if your very clever. I don't recommend this path.
The coding part of it is harder than C# and VS. But you should be able to almost straight copy my code. Its in C.
#41633 Powerful Aquarium Lighting
Posted by Magpie on 16 December 2012 - 10:14 PM in General Discussion
#41454 Powerful Aquarium Lighting
Posted by Magpie on 12 December 2012 - 11:43 PM in General Discussion
Attached Files
- Cheapass current limited supply.zip 701bytes 1 downloads
#41357 Powerful Aquarium Lighting
Posted by Magpie on 10 December 2012 - 11:19 PM in General Discussion
these are suitable.
BC337-40RL1GOSCT-ND
AE10015-ND
I would use through hole stuff for the current limiter and put it on vero board.Are these ok for the LV317?
Can you get a cheap resistor pack somewhere like Futurlec
Use ltspice to simulate, it is way easier to use than Kicad, you will learn heaps. Play with your current limited supply. When you get it right then you can order.
heat proof tape I haven't used it yet but from what I have heard it is useful.
Inductor will be fine, I have done it this way twice now.Final question what exact IC holders did you get, because looking at the ones I have that don't have enough pins theres not a heap of space for the little inductor, I'm sure I've seen thinner versions before but thought its worth checking?
Doesn't really matter, even if it is 50mA. If you have the leds fused properly then you can use the leds. Dont change the sense resistor. Just change a constant in the firmware.In terms of LED load replacement in the form of resistors what would you suggest and would you suggest changing my current sense to a lower value for initial testing i.e. to produce say 300ma instead of 700ma or just do it in the firmware? If so can you suggest some component characteristics for either/both?
I haven't actually got a battery or a solar panel yet. This was actually my one of my other work projects, but they wont finish it now. I am going to keep going for my own benefit. Hopefully I will sell the product back to them, at vastly inflated prices of course. (Heh Heh Heh)The solar charger sounds cool, have you implemented any battery management?
I am monitoring the charger current and the load current because the battery current is actually the difference in these. If you charge too slowly you cause sulphation apparently. Many systems don't measure the load current, I also need to temperature compensate.
Previously one of our installs stuffed up because the ambient temp was 45C and we fried all the batteries.
the client was ropeable, all I could say is sorry our equipment is not suitable, and withdrew the solar unit from sale.
Watch a few vids and practice your heat gun before trying to do the full board. Maybe do the electrolytics with the iron.
One guy said there is no such thing as too little solder paste.
Try to roughly follow the suggested temperature profile. Warm up slowly, dont stay more than 30-60 seconds at full temp and cool down steadily. You know it's too hot if you burn the boards.
#39781 Powerful Aquarium Lighting
Posted by Magpie on 21 November 2012 - 01:07 AM in General Discussion
#33122 Powerful Aquarium Lighting
Posted by Magpie on 04 August 2012 - 11:58 PM in General Discussion
Firstly, put your Kicad stuff including libs and mods into source control, if you are going to work effectively this is a must, being a programmer you probably already use source control, it is so easy to make a mistake by clicking the wrong button, that rollback will save you and give you clues into how it all works and tell you what has been changed.There are foot prints for this type of cap but none that are exact so I wanted to edit the component to make one for my cap, but couldn't workout how to do this in the editor. The lines didn't seem selectable and the couple of pdfs I read didn't seem to help much either?
Just to start by giving everything standard footprints. Doesn't matter if the footprints are wrong as long as the pins are the same.
Then in pcb editor right click and edit module on the components that need changing. Then on each pin you can edit by right clicking. The pads are normally simple shapes, so you can edit the them by just changing the sizes and offsets in the text boxes.
If you need a complicated pad shape you can make it as two or more separate pins but give them the same pin number. This is a strange but necessary work around and it does work fine.
Work out how to save these modified mods into your own mod library and then associate them.
Did you see a youtube video on Kicad, I found one in particular it quite useful.
the footprints for the caps don't need to be exact, if it roughly good enough it should solder ok, you are better off using a standard footprint because you might change caps anyway.
Also there is a difference on components between the actual footprint and the solder pad needed. the solder pad is normally a bit bigger around the edges of the component so you can stick the point of the soldering iron onto the pad itself.
that's what I did, the caps need to be close to the processor and the resistors are not so critical. I would go with that unless you have a specific reason. The bigger components are easier to work with.Am I right in saying all the resistors should 1206 and all the other caps should be 0805?
ps. the reason I chose 4.7uF through hole is because I had 100 of them already.
#33111 Powerful Aquarium Lighting
Posted by Magpie on 04 August 2012 - 12:15 PM in General Discussion
#29451 Powerful Aquarium Lighting
Posted by Magpie on 21 May 2012 - 12:04 AM in General Discussion
The 5 volt output is not meant to be used by you so don't use it. It is used internally to power the logic of the chip.
It needs a decoupling capactior so if something suddenly turns on or off your logic still has close enough to 5 volts. ( I think it is 5v).
The thing about decoupling capacitors is that they don't need to be accurate, they just need to be big enough and fast enough, Surface mount ceramic is fast enough and 2.2u or 4.7u (which is what I used) is big enough.
In short 2.2uF is fine.
I think the 180k is only a ball park number, it is about the minimum off time. It doesn't really matter as long as it is fairly close to that number.Finally the 180k does the equation for this take in to account the RSense and if so do I need to calculate this myself for my RSense of 0.285? Is there a suggested power rating for these?
do the power calculations for the 180k resistor. if your maximum ciruit voltage is 12V then your maximum power in the 180k = 12 * 12 / 180000 = 5uW.
If you do more electronics you will start to see that a high resistance equates to low power dissipation.
So if I was using say a 5v supply for 1 LED and a 12v supply for 3 LEDs is there anything else that needs changing in the circuit?
Minimum input voltage to the NCL30160 = 6.3 volts.
Just run them all off 12 volts. You wont loose much.
Are you spinning your own board or using vero board?
I have bought 100 leds and designed my own mcpcb, they should arrive this week, I hope the mcpcbs don't have any errors.
#30556 Powerful Aquarium Lighting
Posted by Magpie on 11 June 2012 - 11:14 PM in General Discussion
#29392 Powerful Aquarium Lighting
Posted by Magpie on 19 May 2012 - 12:36 PM in General Discussion
Sorry you are right, it is 200mV average, but it turns on at 180mv and off at 220mV.Where is the 180mv from? I remember 200mv for the current sense? Also is this squared as 180 or as .18?
Lets work in Ohms, volts and amps. forget the millis.
You need 0.285Ohms to give you 0.7A.
the current sense average voltage = 0.2volts
So the current sense power will be V * V / R for each resistor.
It wont be much but we need to check in case you go surface mount.
0.2 * 0.2 / R
worst case is 0.75 ohm
P = 0.2 * 0.2 / 0.75 = 0.053 watts, ok I think you are safe with three resistors.
These resistors will have maximum voltage of 220mv on them, your are ok by a factor of 1000. You will be hard pressed to find a resistor whose maximum voltage wouldn't be enough. So don't worry about voltage and use at least 125mWatt resistors.Does the reisitor voltage matter I found some that are 250mWatt and 200V rated is this ok?
the other resistor from memory was quite difficult to calculate, but I used 180kOhm
#28278 Powerful Aquarium Lighting
Posted by Magpie on 29 April 2012 - 12:28 AM in General Discussion
I guess the length of the run for the leds has a few issues.pcb, does it make a difference the run of wire between the leds and the drivers?
more inductance, but in our case this is a good thing.
more resistance therefore more losses which may not be that important for you
more emi noise generated. the NCL30160 will generate noise in two bands:
one at the hysteric switch frequency, which will vary and be anywhere from 100kHz to 1.4 Mhz, the inductor will be continuous at this frequency so it will not be and issue. the current change will be about +- 25% from 700mA.
The other one is the worry. When you are dimming you have to supply the NCL30160 with a square wave at 0-20khz. This will switch the enable pin of the converter. At this point you are switching 0-700mA at say 20khz. This is switched along the length of the cable run.I
I don't know if this will be a problem, but I can imagine it is not any worse than a lot of other things in your life. To minimise the interferance you could use cat 5 cable as it is twisted pair which will reduced the noise a lot. The cat 5 have quite a decent conductor cross section too. I would say fine for 700mA.
If you went with the cat 5 (at 24awg not 26) at a distance of 3m, or 6m return trip.
your cable resistance is 84.22mOhm/ metre. which equals 505mOhms.
voltage drop for your single led circuit with 24 AWG = 505mOhms * 700mA = 353 mVolts.
Vsense = 180mV
Vfet = 700mA * 42mOhm = 29mV
Vind = 700mA * 36mOhm = 25.2mV
Vled = 3volts?
As a ball park electrical efficiency calc. Your led drive output voltage = Vled + Vind(dc) + Vsense + Vcable + Vfet. = 3587 millivolts.
eff = Vled/Vdrive = 83.6%
Though most of the heat goes into the 6 metres of cable.
alternatively 1mm2 cable at same length is 34.6mVolts.
giving drive voltage of 3.269 volts.
giving efficiency of 91.7%
there is also switching losses but these will be smaller in comparison, and hard to work out.
I think I would try the thicker wire, which will be hard to get as twisted pair, and see if you get any noise problems particularly in your sound equipment.
the other point worth noting is if you have leds in series where possible, the losses are only per string, not per led, this is why I want to run large strings of leds
I will obviously be running up against the same issues in my Led stuff.
#28109 Powerful Aquarium Lighting
Posted by Magpie on 26 April 2012 - 12:34 AM in General Discussion
If you go veroboard then you need mostly through hole components.
if you go pcb then surface mount is a good option.
Last night I put together some of my Steffshield project, and I must say it looks really good on the pcb, but I have at least 4 errors but luckily no showstoppers.
I have a pile of things going on right now, but I will give you part numbers for the bits you want.
Remember to give the tracks between high current components short paths, NCL, diode, inductor, sense resistor.
caps need to be right next to the pins.
TVS needs to be betwen the ground and Vin on the only path before the Vin Cap, with very short leads.
= 285 milliohms, better get a new calc.Rsense = 200mv/700ma = 290ohms
Leave room for 2 resistors here, so you can use parallel to tweak the current.
When i get the chance I will draw something. (within a couple of days)
#31272 Powerful Aquarium Lighting
Posted by Magpie on 27 June 2012 - 11:48 PM in General Discussion
#31278 Powerful Aquarium Lighting
Posted by Magpie on 28 June 2012 - 01:12 AM in General Discussion
But the Attiny will be Dip, just so I am sure that I can program it, I have never done an ISP header before and a cock up here would be catastrophic, the big inductors will be dip, and the connectors and fuse holder.
I think the program will be very small, probably the tiny261 will be fine.
I assume so but I really don't know.I have an avr ISP mk2 will that do the trick?
Those connectors look good (your favourite).
I think I want the screw in onthe flying lead and the L shaped black header pins, probably I will go for 5mm.
I will draw the pcb at 5mm.
#32860 Powerful Aquarium Lighting
Posted by Magpie on 29 July 2012 - 12:09 AM in General Discussion
#32854 Powerful Aquarium Lighting
Posted by Magpie on 28 July 2012 - 02:41 PM in General Discussion
I have just been working on it now,
Sorry the cap was 3.9nF. No it is for the black regulator.Finally your last point was about 10K resistors and 39pf caps, I can see some 10Ks on the BOM but do I need to add the caps and if so will these do? CC1206JRNPO9BN390
I haven't fully tested the boards, only the black regulator.
I have just modified my original code to support the ADC differences, I am using differential inputs on the current sense, and one sided for the dimmers. You will put your TLC5940 square wave into the dimmer inputs, Share the grounds between the chips. the dimmer input must be 0-5v. PWM Square wave is fine, use a frequency just about 20khz or so.
For firmware I am using Amtel Studio 6 and an AVR Dragon, it seems to download ok, if I have any problems I will go back to version 4 which did work.
Last thing I need to do is rescale the current sense, which is just a constant.
Then turn it on and see what happens. I have been really busy but will try to get lights tomorrow.
Have you seen Mikes electric stuff he has a good video on small scale production, there is a link on hanzibals audio project that I posted.
They are quite good but I personally wouldn't use them as their DC resistance is a bit high at 334mOhms for 330uH. The smaller the package the higher the resistance.I have found some indutors on ebay that are really reasonable don't know what you think? SMT DS3316P
But that may be fine for you as super efficiency is not your main priority. The only way to reduce the resistance for the inductance is to go bigger.
You will have to weigh it up for your situation.
I just went with cheapie chinese phoenix connectors, for power and leds, but 0.1 inch pitch pcb pins for the dimmer and the ISP header. (both 2x3)I will also look at connectors as well at some point what did you go for in the end for power, LEDs and control signal?
497-5927-2-ND is wrong, use 497-5938-1-ND it is 5v operating voltage tvs.On the BOM I have made a few comments and corrections based on your advice I think I am almost ready to order now but just want to make sure I have got everything on there.
the little smd inductor is fine use that.
power inductor: see above it is ok but you might want to use bigger.
39pf dont use
the fet is still wrong, see previous post. If you are using 5 volts on the fet gate you need a logic level fet.
#32732 Powerful Aquarium Lighting
Posted by Magpie on 26 July 2012 - 11:40 PM in General Discussion
#31591 Powerful Aquarium Lighting
Posted by Magpie on 04 July 2012 - 11:09 PM in General Discussion
#27860 Powerful Aquarium Lighting
Posted by Magpie on 22 April 2012 - 12:55 AM in General Discussion
Better to bring it down to some lowish dc voltage and use a led driver for each channel from there.
I was talking on another forum about my troubles with the NCL30160 and a couple of things were suggested.
1. run at a lower voltage ie. 12 or 24 even though the chip is rated at 40V
2. use a transient suppression diode across the vin. one that suppresses at a voltage just above the vin you want to use.
3. bread boarding high frequency power circuits is fraught with difficulty, and could have been the cause of some of the problems
Also I said before you may get away without the inductors but I think you need them unless your nominal led string voltage is near your maximum dc voltage.
eg. 3 leds at 3 volts = 9 volts running from 12v probably doesn't need the inductor.
but 1 led at 3 volts = 3 volts running from 12v probably does need the inductor because the instantaneous voltage across the led may cause a large instantaneous current that is too much for the led.
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