Why did this student's windmill make low voltage?

Discussion in 'General Electronics Chat' started by bookstoreboy, Feb 26, 2016.

  1. bookstoreboy

    Thread Starter New Member

    Feb 15, 2016
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    Here's a slow pitch for my first homework question. This happened a long time ago I'm just wondering if I'd tried all I could.

    Student comes into the lab. Group project was a windmill with a generator on it. Teacher gave him the "generator" (I'm pretty sure it was some motor). Nice windmill, he made, like a squirrel cage fan out of glued up posterboard. So I take him to electronics.
    Hook thing up to bench multimeter in DC, spin. Two volts.
    Bench multimeter in AC, spin. Like, no volts.
    Tried another meter, same thing. Student insists it should make a bunch of volts.
    I put some resistor across the "generator" and put an o-scope in series. I just wanted to make sure this thing wasn't putting out AC or something silly. Only amplitude changed by some mVolts, did not look like ac.
    I really wanted to see what kind of motor it was but they'd buried it in wood and I couldn't see it. It spun free so it wasn't like a stepper motor, but certainly nothing real high torque.

    The windmill was very easy to spin by hand and my thinking is that if it made any power worth making it would have been harder to turn... Probably so hard that their design would need a gale to work.
    My question is what would you have tried?
     
  2. WBahn

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    Mar 31, 2012
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    I don't see what the homework question is here or what your question about it is.

    Is the tale the homework question and you are being asked what else could have been tried?
     
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    I think yo tried all you could do. Based on your story and my experience with this high school science project, I would guess that there is some slippage in the connection of the fan and the motor shaft (or some other intermediate connection in between).
     
  4. bookstoreboy

    Thread Starter New Member

    Feb 15, 2016
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    I guess I misposted. Feel free to move/delete/etc.
    I'm just curious what an EE with a basic electronics desk would have tried in the same situation.
     
  5. WBahn

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    In order to figure out where best to move the post, please describe what you meant by, "Here is a slow pitch for my first homework question." What, exactly, is the homework question?
     
  6. WBahn

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    There's something pretty obvious he could have tried, but I don't want to go any further until I have a better feel for what the homework question actually is.
     
  7. GopherT

    AAC Fanatic!

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    Why are you obsessed about the homework aspect of this question? He clearly said it is an ancient story, he was not the student and it doesn't have to be moved anywhere.

    What is the other thing he could have done?
     
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  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    To generate the motor would need a field of some kind, a permanent magnet etc, to detect this you can short the wires together and see if it make it hard to spin.
    An AC induction motor will not generate.
    Max.
     
  9. WBahn

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    Mar 31, 2012
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    Look at his other threads. They are very much homework from someone that is just beginning to learn about electronics. He himself stated that this was a "slow pitch for his first homework problem". So it seems more likely, to me, that the "story" is not HIS story, but rather a "story problem".
     
  10. GopherT

    AAC Fanatic!

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    Ok. Perfectly plausible option. NIce to know you've taken the time to research this member and vetted his motivations as "Questionable". So, umm.... why are you acting like you will get arrested if you blurt out the answer before the OP discloses more information about his motivations for asking the question?
     
    Last edited: Feb 28, 2016
  11. WBahn

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    And why are you going out of your way, again, to pick a fight?

    I'm not going to get arrested if I blurt out the answer and I'm not acting like I will be. I simply CHOOSE not to blurt out an answer and, rather, to adhere to the Homework Help guidelines (which is the forum he posted in and is the explicit information given in the very first sentence of his post).
     
  12. GopherT

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    Psych minor and hobbyist psych miner.
     
    Last edited: Feb 27, 2016
  13. shortbus

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    Seems like some one doesn't like to be treated like he treats poster's. :)
     
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  14. bookstoreboy

    Thread Starter New Member

    Feb 15, 2016
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    Wow this board is out of my league. It's a cold case from last semester, gee whiz.
    Thanks to the two (of twelve) relevent replies.

    Here's a thought: There isn't another thing to try. Now, WBhan can either:
    -Prove me wrong and outsmart world+dog with the obvious tier one diagnostic method that none of us know, or
    -Uphold forum rules and know that none of the board users understand basic troubleshooting.
    You come out ahead either way, WBhan!

    From Adam Savages Ten Commandments for Makers:
    5: Ask for help.
    6: Share your methods and knowledge and don't make them a secret.
     
  15. GopherT

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    He has a thought somewhere that prevents him from giving an answer when the question is posted in the Homework section. We would rather cosplay Socrates until the end of time on principle.

    Click "report" at the bottom left of this post and ask a moderator to move this thread to Electronics Chat sub-forum. It will get better visibility. It is clearly not homework anyhow.
     
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  16. WBahn

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    Mar 31, 2012
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    I don't care to outsmart either you or the world, and by resorting to such tactics you are simply using one of the very common ways that people looking to cheat on a homework assignment use to try to trick someone into giving them the answer. I'm neither going to rise to the bait or fall for the trick -- and just employing such childish tactics makes me less willing to assist you at all.

    I asked you to explain the context of the question and how it applied to a homework question (which YOU said it was). You opted not to address that question, so I opted not to disclose more information. The ball was in your court.

    The thing that you could have done differently has already basically been mentioned by another poster, though I had gone into more detail about how you could tease more information out of it. I actually wrote that post as my initial response and even posted it, before wondering whether that was what YOU were supposed to do as part of what YOU stated was a homework question. So I deleted the post and asked you to clarify things so that I could decide what was a reasonable amount of information to give in the context of a homework question.
     
  17. WBahn

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    Yeah, I have this silly thought that just giving people the answers to their homework doesn't do them much good. Yes, I realize it's a strange and incomprehensible concept for some people, but there it is.

    So something that someone clearly identifies as their first homework question clearly cannot be homework.

    I tried, explicitly, to get the TS to provide enough clarification so that the thread could be moved. Yes, they can report it and see if they can convince the other mods that a post clearly labeled as a homework question isn't a homework question.
     
  18. GopherT

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    Really? I read it differently. He clearly says it is a "homework question". Meaning, from my point of view, his first post in the homework sub-forum. In his second sentence (first post), he said it happened "a long time ago" which was clarified as, last semester.

    He went on to say it could be moved or deleted if an autopsy of an old school project did not get resolved in class was not considered "homework".

    Finally he said he didn't know what kind of motor was in the project because it was not visible and he was trying to get the most possible voltage out of another person's project.


    PS: Thanks for giving me two turns in a row.
     
    Last edited: Feb 28, 2016
  19. bookstoreboy

    Thread Starter New Member

    Feb 15, 2016
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    EE's, Pe's, CET's, EET's, and other abbreviations as honored:
    I cannot delete this thread.There is no option?
    GopherT, you're a champ, I tried to Report but I do not seem to have that button (because I'm new maybe?)
    I cannot edit the post and wholly remove 'homework' from the thing.
    If I did Report it it'd go to WBahn anyway right? I'm off to a super start for mentioning homework, presumably cheating on homework, "acting childish", presumably assuming formulas magically appear in books w/o calculus, generally being sub-engineer so I'm not holding my breath for moderation assistance. Plus I messed up cap math yesterday, more cheating on homework, and apparently I need to be typed at with CAPS for EMPHASIS, as it's apparent that I am incapable of comprehending maturely authored text.
     
  20. WBahn

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    Mar 31, 2012
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    We don't delete threads unless they violate the User Agreement.

    New members can't delete or edit threads because there have been way too many times when someone has blatantly tried to cheat (up to an including offering to pay someone to do their work for them) and then tried to delete it to remove fingerprints once they discovered that their professors were members.

    It would go to the moderating staff and I would recuse myself since I am a participant, which is why I said that you would have to convince the other mods.

    Don't forget wearing a chip on your shoulder.

    Please understand that when you post something here, especially your initial posts, we only have what you actually include in your post to base our impressions on. If you look through Homework Help you will see poster after poster after poster that only wants someone to do their homework for them. So it's not surprising when you start off in a similar vein that you will be thought of similarly. When you won't answer questions and get defensive, then that doesn't help your side.
     
    Last edited: Feb 28, 2016
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