hello to advice on power supplies

Discussion in 'The Projects Forum' started by madman6233, Mar 8, 2011.

  1. madman6233

    Thread Starter New Member

    Mar 4, 2011
    18
    1
    Hello I am very new here so any advice or tricks about finding things would be greatly appreciated!,
    I have been for weeks now been working on a psu project and have decided to go active finally the information on this page has been so incredibly helpful and when i have the time I look forward to filling the large gaps in my knowledge.
    to the point though, I have 2 converted comp units working one has .5A on the neg 12V side and the other .8A largest ive found so far. They are already fiddled with and put out what seems to be a constant source so now I need to vary it I have bought lots of pots and a few rheostats , and fried some for sure.
    I have managed to get one working but the lack of amperage on the neg side has me wondering how this all works out.
    I am trying now to find a prog that will let me draw out for yall jjust w338hat i did but I was told to add the pos 12V and the -12V and the circuit would put out around 24 minus the Vdrop and resist factors right?
    so if my desired usage is around 6-9 volts and using the lm317 (all I could find locally) I am falling short of my aim for 2 amps.
    now I did go order a 338 through my father and was i surprised when I ended up with nte935 after finding info I decided to build a similar circuit to what is in the experiments section as well as from the rest of my studying here (thread after thread) and it was seeming to work fine Though with this mount I am not sure how one tells Vin and ADJ apart I know the case is my Vout that one was easy. Anyway I fried my little .25watt POTENTIOMETER SO DECIDED TO TRY RHAT THREE POT CIRCUIT IN EXP BUT I ALSO NOTICED THE HEAT ALMOST IMMEDIATELY start to build up and I sank it to a 4" x @.5" nearly 1/8" thick piece of aluminum and thought that would do it for sure and yes i remembered grease. but it wasn't good enough my pot started to smoke is the 22. blah volts to steep a drop for me would i do better combining my pos 12V @20 A along with say the pos5V @ 20 amps then regulating or keep trying the other till i get it.

    ,
    Also about the third time I didnt get it right I decided to get a real 12V power supply kinda old but it's a ROYAL SOUND regulated DC supply @ 3 Amps. And when I was testing my last circuits something happened and its not producing an output now so ill keep trying to figure what went wrong there seems like a neat small regulation circuit in it so ill try.

    By now I have like 5 of those darn 317 and am thinking of trying multiple regulators being available for whatever.
    right now i Am researching if I can run them in parallel like the NATIONAL datasheet says but it has me confused still. has anyone managed to put 2 Lm317s in series and acheived a 3 Amp regulator Will try and figure out how to add pic of circuit and schematic I first tried
    ,
    I think maybe one out of three aint bad.
    thanks so much for the enjoyment Ive already gotten lurking through here already
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,782
    940
    use the supply +12V sides. They are capable of much more current.

    by connecting the +12 of one supply with the common lead from the other supply, you create a +12 V supply.

    The unit 1 common becomes -12 V
    The unit 1 +12V, and the unit 2 common, become the ground level.
    The unit 2 +12V becomes the +12V.

    ( you should try not to let the two power supply cases touch each other, not good if the common is tied to earth ground in either unit)
     
  3. Wendy

    Moderator

    Mar 24, 2008
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  4. madman6233

    Thread Starter New Member

    Mar 4, 2011
    18
    1
    Thank you I truly hadn't considered that as an option but you point it out I even have a large case so that I could throw them both into and three fans might do the trick but space in our trailer is at a premium I would use a wall unit (you call them ???) but no way was i gonna get 2A from them although I have a 1500 milliamp and a 600 milliamp wall unit as well but the 1500 is a switchable with like 6 settings so I'd like to keep it available.
     
  5. madman6233

    Thread Starter New Member

    Mar 4, 2011
    18
    1
    I thought that I would mainly get a few people telling me i was going about this wrong or such but not really. wish i could send out thanks but oh well To you that did I appreciate that you had other ways to accomplish what I needed. I still want to finish this and I really like the idea of running lm317's in parallel but I am thinking that a switch power supply is all wrong for this purpose I am running what appears to be a circuit that turns itself off as soon as it is turned on over and over so thats gonna end up with all sorts of issues i am to dumb to understand totally I am trying to learn about impedance and electro magnets but till then I decided that too much was what was killing me by stepping down all the way from 23V to running under 12 there was too much and I was giving off an unsafe amount of heat. still have all the parts gathered seems a waste but there you are I went out yesterday and found a wall wort? It's 15V @ 4 amps hopefully this will run things on the cooler side and I will try and figure out more about these extra transformers I have lying around so i can construct what my gut tells me is right.
     
  6. wayneh

    Expert

    Sep 9, 2010
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    If you want more people to reply, try using punctuation and grammar. It DOES matter. I can't follow your posts and simply move on the next help request. We only have so much time to give.
     
  7. madman6233

    Thread Starter New Member

    Mar 4, 2011
    18
    1
    Thanks very much bill I finally have A working adjustable. I will be trying to build the 5 amp version next with the 935 but I understand now about how my heat sink issues will crop up. I think I have a handle on it but still I had to try 4 out on the lm317 before I was happy with the results. I too understand time constraints with a 6 month old boy I have little time for hobbies, or the internet and my research let alone proper grammar so sorry if it is an issue but with all the posts i have read with poor spelling and unclear statements. that was the only remand i have seen. and I for one thought it extremely uncalled for so bye.
     
  8. wayneh

    Expert

    Sep 9, 2010
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    Not the first madman I've ticked off unintentionally. Whatever happened to the spirit of constructive criticism?
     
  9. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,782
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    Evryone is a winnir in schools these days Wayne. Even bad spellers get 'feel good' awards. I can't blame them for growing up thinking they are special and no one, but NO ONE, can point out such errors without incurring 'their wrath'. Leaving school for the big bad REAL world, makes for a bunched of pissed of young people. They finally see that they have to earn respect and work hard just for someone to spit on them for the effort.

    :)

    (edit:)On re-reading, this was said as an in general observation about these 'types' of postings. I suspect this poster, (madman) is probably not normally a person that is perceived this way by his peers. Ah! the subtlety of the human languages. SO MUCH of its interpretation relies on a facial expression, and that is always missing from this new mode of communication.
     
    Last edited: Mar 14, 2011
  10. wayneh

    Expert

    Sep 9, 2010
    12,100
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    So true. I remember when e-mail first came along it was very difficult to write brief messages that didn't come off as harsher than intended. Nobody can "see" that difference anymore and it can't be because we've become better writers. We've just become used to a coarser form of communication and have thicker hides.
     
  11. madman6233

    Thread Starter New Member

    Mar 4, 2011
    18
    1
    I can see that my grammar and punctuation is a factor in how i am perceived so I am sorry if it is difficult to follow.
    It is true I paid little attention to these things all throughout my schooling, also I did horrible on these portions of my college entrance exams causing me to be ineligible for the awarded scholarship i had received. So i enlisted in the navy which gave me a half-assed electronics education.
    anyway I went back to the lessons here and found out what i am powering is a "drop-off motor" and now i need to figure out electromagnets as well.
    I have decided to try and make a current and voltage regulated supply so i can better control how strong the coils are pulling (current) as well as how fast they are doing so (voltage).
    I am not sure, that simply seems to be what I am observing.
    I truly appreciate all the help i've been given and can take criticism when I am not totally frustrated like I was in the middle of that last attempt.
    so back i go to study the designs available.
    How should I go about testing the two supplies I have to see what actual amperage I am using when I am running my machine? total newbie question I know but the analog meter I have apparently needs to be upgraded to a digital this is my next large item purchase anyway thanks again.
     
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