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UK Simple circuit, can anyone make it for me?

Discussion in 'General Electronics Discussion' started by a.mlw.walker, Nov 18, 2012.

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  1. a.mlw.walker

    a.mlw.walker

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    Nov 15, 2011
    Hi,
    I have two simple circuits, requiring few components, they can be made single sided no problem, just dont have the equipment or experience, and only need one so dont want to go to company. Needs to be in UK, cos need it back by next weekend.
    Can send schematics.
    One contains: mega1284, a microsd card, crystal, and a breakout board - to be soldered on (by me), obviously couple of resistors, power button etc...
    The other contains, a mega328p, crystal, a button and space for breakout board

    Both pretty simple, if you reckon you can do it (remember surface mount where possible) Give me a shout, and a price (obviously...)
    Cheers
    Alex
     
  2. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    The time constraint you have laid out is not unreal (but close) it's going to cost you a small fortune in an attempt to make this timeline... Designing two PC boards same day, Getting two boards produced with 24/48 hour turn and overnight delivery, securing parts 24/48 hour delivery and flipping a complete unit back to you in 5 days only happens with a LOT of extra money pumped into the project and no hiccups... $100s in additional shipping fees and several hundreds of dollars in rush fees over and above the cost of actually doing the work...

    Good luck, with every passing minute your request gets harder...
     
  3. a.mlw.walker

    a.mlw.walker

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    Nov 15, 2011
    really...

    Really?
    If I give say you the schematics, and they are as simple as I said they are, (forgot watch battery holder) how long would it take you to design the pcbs? theres no more than 10 connections a board.
    Then if you were going to make them at home, meanwhile me ordering the parts from say digikey to be delivered 24 hours later, how long would it take you at home to make the pcbs and assemble them, I cant see that not being more than a days work...?
     
  4. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    Depends, is there space or shape limitations? SMD or through hole? Hard to guess at what is involved...

    In the end yeah, it can probably be done in a few hours if someone made it a priority, but that generally cost...

    I quit making boards at home years ago except for rare occasions, I just consider them too much work for the trouble in most cases... I'm not alone in this respect, a lot of designers won't be bothered with making boards for one offs without significant upcharges... I was factoring in real production house boards not home etched in my lead times...

    This wasn't detailed in you original post, but do note this is a 2-3 day work week in the US, and I don't know how that might effect your ability to secure parts if they are not stocked locally... For me I would have to order supplies in the next 24 hours to make sure I would have them for this week... Pretty much a dead week for productivity in the US...

    Sure it can be done in a day if I dropped everything else and pushed everyone else's job to the side for yours... That assumes I had the supplies on hand to do it... But, most people will expect compensation for dropping everything for your project...

    As I said good luck, it's a tight schedule and hopefully you find someone that can accommodate...

    As a fellow friend of mine used to tell people, "It's not my problem that you need it in a hurry, but if you want to make it my problem I'm going to make it worth my while..."
     
    Last edited: Nov 18, 2012
  5. a.mlw.walker

    a.mlw.walker

    39
    0
    Nov 15, 2011
    ok...

    OK can you help me make the attached schematic into a pcb (small), I have little experience with this, and I now understand I wont get a week turn around, but I can go to a prototype manufacturer with gerber files...
    Thanks
    Alex
     

    Attached Files:

  6. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    To be blunt, this is not exactly a 'simple' circuit, the nRF24L01 chip in QFN20 4x4 is not something that is suitable for home etching in most cases, leaving you really with little choice but to get it manufactured if you want reliability... Second being a radio chip it requires a specific board layout to perform as expected, not just slapped down, the datasheet goes into this detail... That layout takes time, and probably prototype testing before finalizing the layout... Third you don't have this radio chip hooked up to anything in your design, so...

    After not seeing the RF chip hooked up I pretty much dismissed the circuit immediately as null and void of function, even though I'm pretty sure that several other connections are not made as the ratsnest when exported to PC board layout appears to be missing several connections, for example S1 only has one connection...

    The short of it, it appears you have a partial circuit not something ready to go to production...
     
  7. a.mlw.walker

    a.mlw.walker

    39
    0
    Nov 15, 2011
    Hi,
    Yeah that was the most recent version of the circuit I had on the laptop I was using when I posted that, the nrf chip is conected to the relevant pins of the atmega, I just wanted to see wha feel you got from the components I was using.
    Basically as far as I can see, regardless of whether I had sent you a completed schematic, it would be far better for me to use a breakout board for the nrf24L01+ as I dont really want to go through the trouble of debugging wireless communication.
    On that basis, the cicuit becomes even simpler and I might be able to have a go at designing it myself.
    Thanks
    Alex
     
  8. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    That schematic file you posted was modified yesterday a mere 3 minutes before you posted it, and thus triggers a failure on my Duck Test... With that I'm done wasting my time...
     
  9. a.mlw.walker

    a.mlw.walker

    39
    0
    Nov 15, 2011
    ?

    Hmm,
    What a ridiculous response, I opened it, made a change I knew needed making so that it made a little more sense (removing the voltage regulator on the nrf24L01+ circuit, because I can just use the other) and then zipped it up. that would "modify it"... So no need to play Sherlock.
    My last response was a conclusion that I undersood what you had said and needed to go back to the drawing board based on you comments about the wireless circuit, so what an unnecessary response from you that was. As far as i see it you have two options:
    1) continue helping people on these forums, and every so often come across someone who doesnt know as much as you - and perhaps you will feel like you are wasting your time.
    2) leave the forums, sit at home, and enjoy the knowledge that you have and are not sharing because you dont like having your time wasted.
     
  10. duke37

    duke37

    5,364
    769
    Jan 9, 2011
    a.mlw.walker

    You have made 31 posts, non as far as I see helpful to anyone else. CocaCola has posted 2828 times, sharing his knowledge over a long time.

    Please do not impugn his integrity.

    Duke
     
  11. a.mlw.walker

    a.mlw.walker

    39
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    Nov 15, 2011
    ...

    I have not impugned his integrity, merely stated that before questioning my actions from across the pond about why a file was modified 3 minutes prior to posting, and stating that he has wasted his time - surely not posting, would be the better option. Negative response (and I don't mean constructive criticism) is not going to help readers of the forum in the future and therefore is not in the interests of the forum. Also it is much much easier to type something negative than it is to say it to someone's face - something notorious about forum threads. I don't see how his comments helped him, me, you or any readers in the future...

    I have not argued about previous help he has given anyone, and I am sure they are grateful for it, all I said was once in a while you may feel that your time is wasted and you need to decide which "side" of the line you stand on.

    Clearly this thread has gone off topic, I understand I need to go back to my drawing board (4 posts ago) and therefore thank you for your comments, I have taken them on board.
    As far as I'm concerned thread closed.
     
  12. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    The short of it you WASTED my time, even if we assume what you say as the fact, you knownly posted a schematic you knew wasn't complete and had errors, never stating the same until called out... You asked for help on designing a PC board for this schematic a schematic you now claim you knew wasn't finished or correct? Why? If you just wanted an opinion the component package or layout question you could have asked such, while stating the schematic wasn't finished, you didn't! Instead you asked for help designing a useless PC board board layout that you now claim you knew was useless as it stood from the get go, aka wasted everyone time...

    As for my comment, I WASTED my time even opening up your file as it was all smoke and mirrors, I have 1001 other things I could have been doing vs wasting my time trying to help you out while you played games, but not sending (what you now claim) isn't the finished design...

    The Duck Test continues to apply where I stand...
     
  13. a.mlw.walker

    a.mlw.walker

    39
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    Nov 15, 2011
    Ahh so you would have saved time if I had said, "the schematic attached isnt quite finished but could you have a look at it to see whether it is possible you could help with the design of the pcb for it", then you being helpful, would have opened it, spent the same 2 minutes glancing at the components, still replied saying wireless circuits are complicated, (I didnt know they need a specific layout - i have seen the circuit suggested in the datasheet, but didnt know it aboslutely had to be like that) and then everyone would have been happy - all the while the same two minutes would have passed and therefore no time would have been wasted...
    But clearly you have wound yourself up on this, so as I said before, moderator, please close this thread.
     
  14. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    That would have been the 'professional' and 'polite' thing to do, especially when you are the one asking for a favor...

    No, I actually spend more then 2 minutes... I didn't have Eagle on this PC so I had to download and install it to even look at your file... Then I spent several minutes trying to figure out why stuff was so whacked since this was a design that was supposed to be done...

    Well that isn't want happened...

    What's clear is that you won't admit fault and want to pass this off as everyone else's problem and fault...

    I'm willing to bet that if asked, you couldn't post a flawless working circuit, as I suspect from my Duck Test, you don't have one, but instead of owe up to that you are pulling everyone's legs...

    All of your post that date back about one year are in regards to seeking help with what I suspect is the same circuit... Nearly 5 months ago, I posted in another of your threads with

    Wanna guess how far that went? It's not all about this thread, it's more so about the fact that you have been popping up asking for help and disappearing every few months for a year in regards to this design... Add it all up, and see the entire picture...
     
  15. a.mlw.walker

    a.mlw.walker

    39
    0
    Nov 15, 2011
    Im sorry if its ****ed you off as much as it clearly has,
    I can post you a real schematic if you like when I get home, although I really think that would be more me proving something to you than you actually interested to see it - as regards to flawless, I would prefer to call it finished, because as you have pointed out I have been coming here for help, so flawless maybe not, but finished I think so.
    I know exactly how far that last thread went, I got in touch with a small company based in Luton, who proceeded to try and charge a serious amount of cash for the job, and ended up getting a university student to make it for me.
    I dont just come here to ask questions without a view to finishing a project, and one day perhaps I will have the knowledge to return the favour and help others.

    Im not passing any buck however, ok maybe I should have stated that the circuit wasn't currently complete - however its easy to see where the nrf would connect to as every pin on it is labelled to very standard spi pins. I really dont think the aggro I have put you through is worth this monster conversation, but if you feel it is, I would like to end it with an apology, and if you would like to see it (i doubt now you are interested in helping) then I will post a final schematic when Im back at my desktop.
     
  16. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    I'm actually quite curious as the one you posted is riddled with many other errors and issues that I have not eluded to... So curiosity is there to see what has actually been finalized...

    A courtesy followup to those that offered to assist you would have been nice vs just disappearing time and time again...

    You didn't asked anyone to assume or take a guess at how the circuit should be finished completed or fixed you asked and I quote

    This to me indicates you wanted a small board designed and the gerber files so you could send out to production... Since you wanted a prototype in hand same week from said schematics, the obvious conclusion is that the circuit is finalized... You never indicated that it's only half the final design riddles with errors or even elude to it being a partial design... It's a complete and utter waste of anyone's time to layout the design you posted, unless you just wanted to waste time and money for some PC board coaster to set drinks on, or practice soldering on...

    You also stated " theres no more than 10 connections a board." I won't even comment on how inaccurate that number was, lets just say you are not even in the same ballpark...

    As I said previous I'm looking at this in it's entirety...
     
  17. a.mlw.walker

    a.mlw.walker

    39
    0
    Nov 15, 2011
    OK CocaCola. I'm home for the weekend now, so I have attached my schematic and an attempt at a brd. I should say before you open it, that there are warnings in the schematic, and the brd has errors - basically the reason I started this thread in the first place, because my understanding of making brd's is not very good. So as you said, take a look for curiosity.

    I have changed one major thing on the board based on your comment the wireless circuits are very hard to construct - I have replaced the wireless circuit with a breakout board.
    Take your best shot, Im sure you will have the evidence to back up all your previous comments.
    Alex
     

    Attached Files:

  18. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    My advice don't bother sending that out, still riddled with issues BIG ONEs that will prevent it from even getting close to functional... You need a working circuit before you layout a board, focus on that first until the circuit is functional making a board is a useless waste of time... It's a holiday weekend in the US and I don't have the time to even begin listing all the issues as I have 3 Turkeys to fry today... But, one HUGE issue is power, the battery you have on there is USELESS in this application, even if you did actually hook it up properly (you didn't)...
     
    Last edited: Nov 22, 2012
  19. a.mlw.walker

    a.mlw.walker

    39
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    Nov 15, 2011
    Turkeys

    You fry turkeys in America, wow. Is it Thanks Giving?

    Hmm, now I think about it I suppose that if I put two 3.3v batteries (the same type) in parallel I'll get double the mAH, and the same voltage. Then i can actually remove the voltage regulator circuitry completely. I hadn't thought of that. I assume there is some weird issue that can occur like fluctuating voltage if you dont use a regulator however. I am already puttig 3.3v into the nrf24L01+ breakout board and its working fine, but I might i might increase the battery power and keep a regulator in the circuit?

    Are your other worries, the same worries that the error checker picked up on - i.e the warnings?
     
  20. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    DESIGN RULE 101, READ THE DATASHEETS AND FULLY UNDERSTAND THEM BEFORE MAKING A DESIGN USING SAID COMPONENTS...;)

    The voltage regulator is useless in your design since it needs +1V to regulate properly... You can't put 3V in and get 3V regulated out, isn't going to happen... As for mAH have you calculated what the devices use in your design? And more so do you know the specified drain capacity of the little 12mm coin cells you have specified? Hint, it's in the datasheets...

    Lets give you a design primer, using said datasheet info, please review the same on your copies of the datasheet...

    First lets look at nominal current drain of the main components, just to get a ballpark of circuit consumption, not perfect but a start...

    NRF24l01 about 10mA
    Mega1284P about 5mA (when it's actually doing something @ 3V - 8MHz)
    SDcard about 20mA - 100mA (varies drastically from manufacture to manufacture, best to factor in worst case so we use 100mA)

    Give or take circuit consumption about maybe 115mA?

    You have battery power from two CR1225 @ 47mAh... Energizer list the continuous drain at 0.064mA... See a problem there when you you are trying to pull 115mA with batteries rated for 0.064mA even times two that is only about 0.128mA continuous, not the 115mA your devices will likely be drawing...

    They also list the cutoff voltage of 2.0V with that 47mAH or so rating, so you will drop bellow 3V real quick and your AVR will likely be on the verge of puke and the SD card will have puked due to lack of proper voltage long before the 47mAh rating is reached... But, even if we pretended that the batteries would work, with you drawing about 115mA using batteries rated @ 47mAH, best case in a perfect world you would get just over an hour of run time, but in reality 15-20 minutes on a good day... But, that is just pretending as we have bigger issues, since the batteries can't feesably supply the nominal current used by the circuit anyway, they will puke before they start... FYI Short circuit current on these batteries is about 100mA to 300ma for 0.5 seconds, this is a short circuit that means full (death bed) potential not continuous like your circuit needs...

    The short of it your circuit is going to PUKE in no time flat, likely before the circuit even stabilizes...

    Have you even bread boarded this design and done any test?

    Did you read the NRF24L01 datasheet yet? You really should, honestly you should... For this matter I'll give you the Cliff Notes version, please look at the first page, under the title Key Features, see the quote bellow...

    It's really not hard to speculate why it's working with a 3.3V input...

    If you want it to actually work that would be one option, both increasing the battery voltage as well as their ability to source the needed current levels...

    Not worth exploring any further, I saw the coin cell and that was enough for me to dismiss it as a viable circuit...

    And yes I deep fry turkeys in peanut oil for Thanksgiving, did it once and have never baked one again...
     
    Last edited: Nov 23, 2012
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