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Coffee maker circuits

  1. May 15, 2013 #1
    Are the two circuits attached the same? "Circuit diagram" is the original schematic file, and "circuit" is the one I tried creating online. Are they the same?

    I am doubtful of the overlapping of the wires and also the power sources.

    Thanks so much!!
     

    Attached Files:

    Last edited by a moderator: May 16, 2013
  2. jcsd
  3. May 16, 2013 #2

    CWatters

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    No. I'm afraid there are lots of differences/issues some of which can't be resolved without additional information.

    If you are trying to build a 9V DC circuit it might be easier not to start with one designed for 230V AC.

    Tell us what you are trying to achieve.
     
  4. May 16, 2013 #3

    sophiecentaur

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    Several issues here. You have to beware about doing very neat presentations of the wrong information. You can fool people that it's kosher!
    At one time,, crossing wires used to be shown as a 'humped bridge' but circuits involving many wires, close together would have been too messy. So the convention, now (afaik) is to assume wires are not soldered together unless there is a joining 'blob' to signifiy a join. But I dont think 'humps' are actually forbidden.
    The "batteries" are clearly not batteries - P5 and P4 (or P3?) are the mains live and neutral connections (possibly they are Pins (P for Pin?). P1 and P2 take the mains further on in the unit (to a lamp?).
    The thermostat symbol is one I'm not familiar with; it looks a bit like a Thermistor. If in doubt, I would use a box with "thermostat" in it. The same applies for the Fan.
    Resistors are usually denoted by rectangles and not zigzags in ISO, afaik.
    There are some commonly used symbols on this link.
     
  5. May 16, 2013 #4
    More information

    Here is what the circuit is for - an appliance.

    The batteries/source is wrong. It has to be a power cord from the wall going through the unit (see diagram attached with this response). How do I show this in the circuit? I put the batteries because I didn't know what else to put.

    Also are the four diodes supposed to be a AC-DC rectifier?
     

    Attached Files:

  6. May 16, 2013 #5

    CWatters

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    Just copy the original circuit. For example next to terminal P5 it says "AC/L" which stands for "AC - Live".

    Do check the spec for the 1n4148. It's been awhile but I think the voltage rating (and possibly other parameters) make it unsuitable for mains voltage applications.
     
  7. May 16, 2013 #6
    Ok, so what do the P's actually look like in real life? The wire connections?
     
  8. May 16, 2013 #7

    CWatters

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    Yes.

    It looks like P3 should be connected to AC/N via another switch or switching device. This device would then controls the motor and the 10ohm heater.

    EDIT: Ignore the above.

    I see that the motor is in series with the 10 Ohm heater....eg the circuit is....

    AC Live -> themostat -> Bridge rec -> motor -> P3 -> 10 ohm heater -> fuse -> AC/N

    So P3 could just be a test point.
     
    Last edited: May 16, 2013
  9. May 16, 2013 #8

    CWatters

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    The P might stand for "pin" or "post" as in "terminal post" - for connecting wires to, perhaps using crimp on connectors.

    Edit: or it could "Pad" as in solder pad.
     
  10. May 16, 2013 #9
    And are the 4 diodes in a rectifier set up? Thanks so much for your help
     
  11. May 16, 2013 #10

    sophiecentaur

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    Yes. It's a bridge rectifier arrangement. I am a bit concerned that, with your limited level of knowledge, you want to get involved with a piece of mains equipment. Even if you don't plan to get inside it yourself, the information you are transcribing will presumably be used by someone else. If they are capable then the original diagram would be quite enough.
     
  12. May 16, 2013 #11
    Hi, actually I'm just trying to make the drawing look better (more professional)
     
  13. May 16, 2013 #12

    sophiecentaur

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    I wonder why.
    In order to make it look professional AND to be accurate, the draughtsman needs to be 'a bit' professional. I used to try to make my prototype circuits look convincing but they only looked right after they'd been through the 'drawing office'. A CAD package, rather like a spell checker, may make things 'look' ok but it doesn't guarantee to make actual sense.

    I would recommend looking at a lot of professionally drawn diagrams and trying to understand them before trying to produce your own. There are many lists of ISO Circuit Symbols available on the Web.This link gives you the most likely symbols. You need to be careful when looking at the many dated circuit diagrams that you can also find - with many weird versions of Capacitors and resistors. If they don't use the conventions in that link I gave you then don't use them as models of good practice. There will be many suitable ones in amongst them, though. The data sheets from modern component manufacturers are a pretty reliable source of properly drawn circuits.
     
  14. May 16, 2013 #13
    Easy there, I am just asking a question since I don't know much about it. You don't have to make condescending comments about my lack of knowledge. Good day
     
  15. May 16, 2013 #14

    sophiecentaur

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    Sorry; I meant no offence but I am actually worried about the safety aspect more than anything else. If you really think you are competent then I unreservedly withdraw any doubts but mains electricity cannot be taken lightly. It's not being condescending to suggest sticking to safe voltage circuits until one is competent enough.
     
  16. May 16, 2013 #15
    I understand and thank you for your concern, but I am merely trying to draw the circuit, nothing else. Thanks
     
  17. May 17, 2013 #16

    CWatters

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    In my opinion the overall layout of the original circuit is quite poor. Could be drawn a lot better to make the flow easier to follow. For example left to right I would show...

    The AC Live and Neutral inputs
    The switch and fuse
    The Thermostat
    The bridge rectifier
    The coils
    The motor and caps
     
  18. May 22, 2013 #17
    Would it be too much to ask if I kindly requested you to draw it out somehow? Thanks sooo much!
     
  19. May 22, 2013 #18

    CWatters

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    Sorry it's only a sketch, I'm a bit short of time. I've used roughly the same symbols the original used.

    The capacitor values are missing off the original. Do you know what type they are? If they are polarised electrolytic then a different symbol should be used.

    I haven't really checked for mistakes. I see I forgot the fuse type/rating info.

    It's possible to argue about some of the details. I'm not claiming drawing conforms to any ISO standards or anything like that.
     

    Attached Files:

  20. May 22, 2013 #19
    Thanks so much

    It looks great! I dont know how much the L and C values are, but I'd like to thank you for your help in the matter!!
     
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