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#46933 USB Audio Device - FINALLY WORKS!!

Posted by Magpie on 09 March 2013 - 01:43 PM in Project Showcase

Hi Hanzibal


On the subject of Oscillators here is a short app note on them. It seemed pretty good. Apart a typo on one of the schematics, where L1 uses a capacitor symbol.




I didn't find to much talk on symmetry though.

#46881 Home Automation

Posted by Magpie on 08 March 2013 - 10:42 AM in General Discussion

So in terms of lighting (mains) are the contactors ok to use and be up to a standard?


An electrician would be allowed to wire contactors into a switch board or subboard, Many switchboards use Din rail mounting. I think this would be the main option for controlling your house wiring. They could run out the isolated switch wires to another box that you would interface too.

But for me I am quite happy with the non automatic light switch.


Are the din rail dimmers ok in the same way the contactors are? If I'm right a normal incandesant bulb uses leading edge dimming right?

Anything can dim the incandescent bulbs, it is the compact flouros and the flouros that dont dim well, especially when its cold.


the only automation I have is temperature logging. Via netduino plus. It monitors my solar hot water and a couple of other places, I was going to get it to automatically turn on the gas booster but I have just been flicking the switch myself, that actually works pretty well so the project didn't need any more.

I once did make an automatic chicken feeder and watering system, with web cam feedback. So I could feed them when on holidays via the web but I couldn't get the mechanical side right so the pellets kept jamming. It looked a bit crazy while it was running and used to freak the chickens out. If you need the plans to this masterpiece I'll open source them. It was controlled by an openWRT wireless router.

#46635 Home Automation

Posted by Magpie on 04 March 2013 - 10:30 PM in General Discussion

Hi McInnes Sounds like your going to be busy for a while. I think the biggest hurdle is regulatory, and that is why the prices are ridiculous. this is partly why I went Isolated Extra Low Voltage for my lights. Because in Aus a light doesn't need approval if it is SELV. Once you are in the SELV domain the House wiring rules no longer apply to your wires. Is it just lighting you want to control? Or specific items? Some Power outlets or all power outlets? individually? With lights you probably only need to run the switch wire back to the node. I assume you will want a local light switch too wont you, you can probably run this as SELV to the micro. With power you are going to have a stack of conductors going in the same direction, so they will be de-rated. You might consider a sub distributlon board or two. You can get small contactors wired into your switch board, maybe you could wire up your own sub boards and put the contactors in your self. And get the sparky to connect to mains. Just run the coil wires out to a SELV box or section, where you can attach your driver circuits. Too Easy. (... cough cough) the other thing is light dimming, this can be a bitch with all the different sorts of dimmers (leading, trailing, universal, cfl) and the cfl ones dont work well anyway. But if you have LEDs it is a lot easier. Also think about some fire detectors, I don't know what is best but if you're doing home electronics I think they are good. One in the lab too.

#46632 Netduino Solar Monitor

Posted by Magpie on 04 March 2013 - 09:30 PM in Project Showcase

Looks great, nice to know what's going on.


I think I would rescale your battery display from 20 -30 volts or similar. otherwise it wont move much.

#46570 USB Audio Device - FINALLY WORKS!!

Posted by Magpie on 03 March 2013 - 08:00 AM in Project Showcase

Hi Hanzibal

I did say I wanted a board but money is a bit tighter these days than last year. But I wont say a definite no as my music is gradually moving to hard disc, and your system could be useful. But I have a few unfinished things I need to do, so a new project is not high on the list.


Did you ever get to the bottom of your Crystal problems or did the oscillator just fix everything? I will probably lay out a board with a crystal soon. I normally just get an internal oscillator on the chip.

#46554 Powerful Aquarium Lighting

Posted by Magpie on 02 March 2013 - 11:39 PM in General Discussion

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 Magpie 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 Magpie on 10 January 2013 - 09:22 PM in General Discussion

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.

#43102 Powerful Aquarium Lighting

Posted by Magpie on 10 January 2013 - 12:57 PM in General Discussion

Heres the project files for steff4.


You need Atmel studio 6 to compile it.


A few things to do to modify it to your purposes.

The main file is Steff4.c

the others are mainly defines and historical. they dont need changing.


Set the fuses on the Attiny to what is at the top of Steff4.c in the comments.


Careful with the fuses you can actually brick it if you are careless, I did this once.


steff4 is only two channel and you have to change the code to 3 channel. 0, 1 and 2

  So create a few more defines eg. //#define PWM_OCR_REGISTER_2

  also create another section in main for channel 3 that uses the channel 3 defines.


You have to set the all the defines 0, 1 and 2  to be correct for your hardware, so you need the attinyX61 data sheet, your hardware should be very similar to mine.


ReadPWMRegister and WritePWMRegister need to be set whether you are using the positive part of the pulse as on or the negative. If you get it wrong it will turn fully on. This is where the current limiter will save you. Your led wont like 5 volts.


When you get that working and only then, uncomment the dimmer section for each channel in main(), also check any defines used here are correct.



I have to fix the function

U16 GetLoadCurrent(S16 sensorCurrent, U16 currentPWMSetting)

to more accurately get the load current from its parameters, as I mentioned before we only measure the fet current.

Lastly I could optimise and or use interrupts, or I could neglect them, it seems to work fine without them.


No doubt you will have many queries about my code, hopefully you can understand it.

I am sure most embedded C people would have a nightmare about the lack of efficiency if they saw it.

You can also run stuff in the simulator, although you have to break and then change variable values to get into some of the code sections.




Attached Files

#42694 Powerful Aquarium Lighting

Posted by Magpie on 04 January 2013 - 11:41 AM in General Discussion

Hi Andy We are just having the hottest day in Hobart for around 40 years, 41.6C. I am sitting with a wet cloth on my head trying to cool down. Did you buy the house? If you did I hope you have a dedicated Aquarium room. the voltage across RL should be 5volts (+/- say 5%) at low currents ( high load resistance) and up till the current limiter kicks in. The Attiny is happy with 3.3v up to 5.5 volts and 5.04 volts sounds just right. You need two current settings very low and normal. Use say 30mA to test for shorts and then say 100mA to see if the led works and then you can probably discard the current limiter for that board.

Cant get some of the links for digikey. the 0.1uf are ok.

goto go sorry back in a few days.

#42542 n00b VB vs C# for dev of a basic sensor monitoring app w networking?

Posted by Magpie on 01 January 2013 - 01:51 PM in General Discussion

Really for the language differences, it comes down to in C# things need to be explicit and VB things are implicit.

I strongly prefer C# because it is explicit, most decisions are ones that you instigated, whereas in VB you get a more stuff that happens when you didn't actually want stuff to happen.Therefore lots of weird errors.

Also in VB you have to write Dim too many times.


One advantage of VB is the For Next loop operators seem to work more easily with the iterators.


That's my 2c.

#42307 Service note: updates to forums

Posted by Magpie on 27 December 2012 - 10:53 PM in General Discussion

Html 5 nice, this might be why some users have compatability issues.


the W3C validator doesn't really like it, but often the errors are the same in 50 places.

not much to worry about but worth a look.


Some of the popups seem a bit unneccessary, but on the whole it looks great.

#41633 Powerful Aquarium Lighting

Posted by Magpie on 16 December 2012 - 10:14 PM in General Discussion

Hi Just a bit of an update. I got my Steff4 boards back which use a similar design to yours. And guess what, no big mistakes. Thats a relief after what happened in the last version. They didn't print my silkscreen though. I have written some code that works for them but came up against some weirdness that took my a while to sort out. Basically we have changed the topology from my original design. Now we are measuring Fet current instead of load current. Looking at the circuit, The Fet current + the Diode current = the load current. At high duty cycle these will be close but at low duty cycle driving into a potential short circuit these will be way off. So we have to adjust for it in software. We know the Rail voltage and the Led load and the Fet current so we can work out the rest, and adjust accordingly. The only thing is that it wont be super accurate or super linear, unless you do some specific calibration and create a map. This circuit would not be good for colour balancing. This is a bit of a shame as one of the selling points of the 5940 was its accuracy, but really the Leds aren't that accurate anyway. When you want I can send some code. I still want to refine it for load short circuit detection. My C code looks like desktop code, it is not optimised yet at all. I wont optimise unless I have to. Almost no macros and passing everything on the stack. C can be so annoying, remember to cast (INT32) each operand up before any multiplication or division, it gets me every time.

#41454 Powerful Aquarium Lighting

Posted by Magpie on 12 December 2012 - 11:43 PM in General Discussion

1.5 amp is fine. any adjustable voltage reg is fine LT1117 is not doubt more expensive but they work in the same way. the transistor just needs to have enough current / power capability to handle the loads. attached is an LTSpice schematic. R2 sets the max current and R3/R4 set the output voltage. It will be a nice clean voltage coming in, from the regulator. I suggest R2 to be say 10 ohms to test the boards for shorts and then 1 ohm to protect the leds while developing/testing the code. Maybe a switch to switch one of the resistors in. Play around with R2 and R4 and RL and see what changes. You need a larger voltage on the wall wart for this because the current limiter and Vreg both use significant voltage. Once you are out of developement phase, you can go back to your 5V wall warts. Assuming your boards pass the test.

Attached Thumbnails

  • Cheapass current limited supply.png

Attached Files

#41357 Powerful Aquarium Lighting

Posted by Magpie on 10 December 2012 - 11:19 PM in General Discussion

I just lost my post when I searched for Digikey parts. here it is again.

these are suitable.

Are these ok for the LV317?

I would use through hole stuff for the current limiter and put it on vero board.

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.

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?

Inductor will be fine, I have done it this way twice now.

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?

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.

The solar charger sounds cool, have you implemented any battery management?

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)

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.

#41311 Powerful Aquarium Lighting

Posted by Magpie on 10 December 2012 - 09:49 AM in General Discussion

It's not so bad being retrenched, I already have a few small electrical jobs come up and I got a few months pay. I am enjoying the different time scale and being at home.
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):

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.

Anyway that's my rant. Apart from that life is very good.

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.

#40485 Powerful Aquarium Lighting

Posted by Magpie on 30 November 2012 - 09:12 AM in General Discussion

Hi BD131 should be ok or even BC337 should be ok for the current limiter. Just need Ic max > 500mA. For the diodes In4004 or In914 or In4148 should be ok. Get at least one LM317 as it will give a very clean supply. Some vero board. A resistor pack? There are no component changes for the separate rails except having 3 input power connectors onto the board 1: Gnd both supplies. 2: +5v for fets and bjts. can be switched mode. 3: +5v for attiny. maybe a linear regulated ie. Nice and clean. On a side note, I was made redundant today. It came as a bit of a shock but I am not so worried, I have a few options, my wife has a job and I need a long holiday. Might do a bit of fishing. I want to stay in electronics but may have to do programming or electricians work.

#40419 Powerful Aquarium Lighting

Posted by Magpie on 29 November 2012 - 12:53 PM in General Discussion

I will get some low blow fuses like you recommended 100ma or so.

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'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?

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.

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 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.

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?

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.

This seems good enough. But you may need to beef up the transistor and lessen the resistance to give say 500mA.

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.

#40278 Powerful Aquarium Lighting

Posted by Magpie on 27 November 2012 - 01:34 AM in General Discussion


For example we have quoted for 500ma per channel, what if either in the firmware or in the netduino code I set the output to 50%? Does the circuit just take what it needs, does the additional power create issues or is this wasted in the form of heat output from the power supply?

This is actually fundamental to the workings of electricity, I didn't realise that you didn't know this stuff.
The way mankind uses electricity is normally at a constant specified voltage, it could have been current but we like voltage.
Loads are often characterised as an impedance or resistance. Sometimes it is constant like a resistor often it is varying like an oven turning on and off or a monitor changing brightness.

When you connect a load to a nominal voltage they work together to find an operating point which is a voltage and also a current (and therefore a power and a resistance too). As long as the load doesnt draw more current than the source can supply then the source or power supply should sit at near its nominal voltage, the load at this operating point will only draw whatever current it needs.
So for a 5v supply.
A resistor 1 ohm will draw 5 amps.
A buck converter led power supply will draw roughly 250mA if it is supplying the led at 3.15V and 300mA.
the same buck converter at pwm of 0% will draw roughly 40mA (due to overhead of the chip and the gate drive) and put out zero amps.
If the buck converter is completely disconnected from the supply then the output voltage will still be 5v but no current will flow.
If there is a short on the board then a large current will flow, and the supply wont be able to provide the full 5 volts, fortunately your fuse will soon blow and completely disconnect the supply.

Also if say 15 channels were at 0ma with the 5v 11A supply, would this mean I could take the other 15 channels up to 1A per channel?

This is true.
Just remember there is a difference between the power supply current and the output LED current. This is because you have a buck converter.
If you used a linear regulator instead of a buck converter, then input and output currents would be the same.
You have a power supply (wall wart) supplying another power supply (led driver) therefore there will be two operating points both dependant on what current the leds want to draw which is dependant on what pwm you set.

I have bought an Atten 858D+ as per Dave's web blog, although I bought before I watched his review and that made me feel like I got a good deal at £30 including postage.

Sounds like a bargain.

Don't start with the big supply use your wall warts first, and start with smalller fuses test the boards individually. Put on a dimmer pot for initial testing.

George Best said.

I spent a lot of money on Women, Booze and Electronics. the rest I just squandered.

possibly misheard.

#40199 Powerful Aquarium Lighting

Posted by Magpie on 25 November 2012 - 10:45 PM in General Discussion

Thanks those caps got me down to about £70!

Lets face it was your diligence not mine. I normally just buy the first thing.
I wouldn't change the BJTS they are good quality and not so expensive and have been used in Steff2.

I think Atten 858D , (Dave does a video too, #167) do a budget heat gun (dont get ZHIAOXIN 858D and YiHUA 858D, and check earthing before using), but If you want to save money a small wedge shaped soldering tip would probably be good enough for the whole job..

Can you think of anything else that will be useful?

Copper braid.

I have had my own mcpcbs manufactured. mcpcb I think it was $30 for 600 peices + $170 for tooling postage and TT payment. <sigh>
You can mount them on FR4 but need thermal vias. Each led doesn't need a huge amount of Al and it depends on a few factors but you can definitely get away with 50mm x 50mm for each XTE or XPG led. Probably even less. Heat sink at the back mean you can place them closer together, but they make a lot of light.
I am using Steff2 in my workshop and it gives enough light, maybe a little more than a single fluoro. 21 leds @ maybe 300mA. I don't think heat will be a big problem.

my calc was 3 x 500mA x 3.15 volts = 4.725W
+ attiny and gate drivers 5v x 100ma = .5W
+ inefficiency = .5W

Total power for 3 channels on one board = 5.725W @ 5v = 1.1 amps.

I'll go to really plain terms now, so in terms of voltage drop in series this would be 3.15v per LED so you would need say 12v, but we get away with 5v as the channels run in parallel right?

? each led has its own channel, in this case there is no series or parrallel. In the 12v 24v, and 36v designs you have the led strings in series. You cant really parrallel the leds without individual power resistors to share the currents equally, this is wasteful so not considered.

Current i.e. the 1 or 1.5 amps we will supply can be larger than the required 700ma plus any other losses, as the circuit will only take what it needs right? Would this increase if say we needed 5 LEDs in a row to say 4A or does current not drop like voltages does in series hence it would still be 1 - 1.5A?

So here's where I get confused, where do Watts come in to the equation?

For example will my 5v 1A wall wart be able to power all 10 of my boards and I guess I would need to distribute the power in a parallel design between the 10 boards right?

If you run 10 boards or 30 channels of 1 led then you will need 1 x 11 amp 5 volt supply. Or you can use 5 x 2.2 amp supplies or 10 x 1.1amp supplies. Dont parrallel the supplies just join the negatives as common. Keep the the positives of the supplies separate to each other.

Try not to overload a supply, you can probably use standard 1amp wall warts but maybe turn the power down a smidge. you can do this in the attiny firmware so that the Netduino firmware cannot cause failure. Check the warmth of the Wall wart while at full load. You don't really need to use wall warts there are other more efficient supplies.

Also I would put a smoke detector in your lab especially while still in development.

#39942 Powerful Aquarium Lighting

Posted by Magpie on 22 November 2012 - 12:10 PM in General Discussion

Sorry those caps were overspecced.

Try these.

on the caps you can go down to 16v which still leaves a comfortable safety factor. None of the caps need accurate tolerances or temp coefficients.

the fets should be at least 20v.
same with the bjts.

I probably waste a bit of my money but then again we aren't just about to buy a house.

#39923 Powerful Aquarium Lighting

Posted by Magpie on 22 November 2012 - 01:49 AM in General Discussion

Yes use the 805s if they fit your footprints. Well spotted. I think I have used the radial ones on some jobs because I once bought 100 of them. No hurry with the Digikey order they only take about 4 days to deliver, so probably wait about 2 more weeks and see if something else you need comes up. £9+ for 30 is way too much, the only ones that are even a bit expensive are the 0.1 ohm. I think I got a syringe of solder from farnel it was about $20. You should keep it cold, so I wrap it in plastic bags and keep it in the freezer.

#39781 Powerful Aquarium Lighting

Posted by Magpie on 21 November 2012 - 01:07 AM in General Discussion

first work out if it's m205 or 3ag. you can get fuses anywhere. get some 2A, 1.5,1A, 500mA and if possible 800mA. futurlec has cheap prices on these. if possible get some 100mA, just for checking if the board is ok. ie no shorts. Or get a current limiting supply. Have you got a voltage supply? quite clean (free of noise) would be good, this means with a wasteful linear regulator like the Netduino has. maybe order a couple of 1A LM317s and you could make something suitable. Remember you have 3 channels at 500mA and 3.15v. + the attiny power + drive circuit + losses. I would say you are looking at 1.5 A at 5V or thereabouts. the caps look good (they are being discontinued because of the pb. dont worry. PB free is difficult and not really worth the effort) the TVS diodes look good. for soldering you can do it by a normal iron. temperature controlled. or solder paste and hot air gun or solder paste and skillet use a eutectic solder if you can. this means it solidifies within 0.1 degree. so 63/37 is good. 60/40 sn/pb is bad. non eutectic as it solidifies in 3 degrees and it is easier to do bad joints. You can use this if you really want to but just make sure the joints are good. the small volume solder pastes are generally eutectic.

#39770 Powerful Aquarium Lighting

Posted by Magpie on 20 November 2012 - 10:39 PM in General Discussion

It will be fine without the solder mask changed. Just be aware that on certain pads there will be no solder mask between them. so check them visually before you power on. Check the close ones.
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.

#39668 Powerful Aquarium Lighting

Posted by Magpie on 19 November 2012 - 10:40 PM in General Discussion

I just got my failed boards back yesterday, they make them in a few days but it takes about 3-4 weeks in the post. the black boards look great shame they don't work. You can see in the gerbers if the board outline is there. When you plot there is a checkbox to put on the board outline layer. the postage to Aus is just 7 dollars I made my Steff4 boards green (yuck) to save money,they are only $25, + 7 dollars postage. in other words just pay the postage might be the best option. my last order was Ordered: 29/10 shipped 6/11 arrived 18/11 thats actually better than expected. One more thing on your Gerbers, I think you should decrease the solder mask clearance. so Set preferences -> dimensions ->Pads Mask Clearance->Solder Mask clearance to 0.0508 mm This will mean the mask almost is exactly the pad. Then re plot the gerbers. Otherwise you can have pads close together that dont have a mask separating them, the solder can bridge these accidently quite easily. I fixed this in Steff4 but it was the case in steff3.

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