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Homework help!

Discussion in 'Electronics Homework Help' started by Becs, Oct 16, 2017.

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  1. Becs


    Oct 16, 2017
    Hi :)

    I'm wondering if there's any kind souls out there who could help son has an assignment for electronics and I have tried to help him with the missing few items he has, but I have no idea at all what I'm doing. So really, I've spent about 3 hours reading lots of things that don't make any sense to me - reading electronics manuals is kind of like reading a foreign language to me - without getting too far at all. I realise this is not really what your forum is intended for, but I would so appreciate it if you could just answer just a few - I'm sure really simple for you guys! - questions?

  2. kellys_eye


    Jun 25, 2010
    Rules state we won't 'do' his homework but until we know the question we can't determine whether this is what we'll end up doing or not!

    We can certainly point him in the right direction if you care to let us in on the details though....
  3. Becs


    Oct 16, 2017
    Oh that's totally fine. I just don't want him to leave holes in it if he can help it, so I'm trying to point him in the right direction - thanks! He needs reference designators and the unit (which seems to be the output? as in mA, kHz etc) for them - he's managed to get almost all of them, with the exception of the reference for 555 integrated circuits and the unit for speakers, switches, microphone, LDRs and LEDs. Is there somewhere you can point me that might have a table or something explaining these ones? All the references he's listed in the assignment don't have these in it, and I'm just not sure if there's a reason for this or if he (and then I) are just not good at looking for the right info. :)
  4. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    Your description is not totally clear. What kind of reference or reference designator (as mentioned at the beginning of your post) do you mean?
    I'm also at a loss when it come to 'units' for speakers, switches etc. Also I dare say I have some experience in the field I don't know in what kind of 'unit' you'd describe a speaker.
    It might help if you post the original assignment - at least that part where the issue of units is mentioned. There may be a misunderstanding of the assignment.
  5. Becs


    Oct 16, 2017
    See, I know nothing about any of this, but I thought the same thing about the unit part :D This is from the assignment:

    Each information sheet must contain the following information:
    ⦁ The definition of the component.
    ⦁ The letter representation of the component.
    ⦁ The unit of measurement, if any, used to measure the value of the component.
    ⦁ The circuit symbol used to represent the component.
    ⦁ The operational principle of the components. (How it works)


    ⦁ Batteries
    ⦁ Resistors
    ⦁ Capacitors
    ⦁ Light Dependent Resistors (LDR’s)
    ⦁ Light Emitting Diodes (LED’s)
    ⦁ Bipolar Transistors
    ⦁ 555 Integrated Circuits (IC’s)
    ⦁ Speakers
    ⦁ Microphones
    ⦁ Switches

    So I'm guessing some of them just don't have a unit. He has filled in all the other details - symbols, definitions etc - but unfortunately due to a tragic family event he missed a week of school - which would have been when they explained the rest in more detail and as I said - I just lack the knowledge to help him much more.
  6. Arouse1973

    Arouse1973 Adam

    Dec 18, 2013
    Have a look on Wiki for reference designators. That should help with some of your questions :)
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    Also, this sort of stuff sounds like it comes straight out of the recommended reading or from the lesson/lecture.

    If be asking if he hasn't skipped out of the required reading or zoned completely out in class.

    If it's the reading, then this is the simplest, just locate the text and make him read it.

    Edit: I missed the "family tragic event" bit, so I will withdraw the implication above, but the solution still stands as a good possibility.

    This sort of question has a style of answer where it's hard to hint at the answer without giving it away.

    However, I'll try to answer for a component not in the list, so you can get an idea of the style of answer that *may* be expected (and I don't know the level of the course, so I don't know how much detail is required for some of the answers)

    Component: inductor

    Definition: an inductor is a component which has the property of having a known (and generally fixed) inductance. Often in the form of a coil of wire, possibly wound on a magnetic core (alternatively it can have no core -- i.e. the core is air).

    Letter representation:. Typically "L" is the letter used to designate an inductor.

    Unit of measurement: Henry (H). 1 H is a large amount of inductance, typical values may be measured in μH, although values between single digit nH and tens of mH are not uncommon.

    Circuit symbol:. There are many forms, here are a few: (google "inductor symbol", and look at the image results). Note that your son may be expected to choose one following a particular standard.

    Operational principle: current through an inductor causes a magnetic field to be created which opposes the chance of current in the inductor. A fixed voltage across an inductor will result in the current rising linearly with time until the core of the inductor saturates. Energy is stored in an inductor in the form of the magnetic field. This energy can be transferred to another coupled inductor (e.g. as in a transformer), or back to the circuit the inductor forms a part of (e.g. in an LC tuned circuit). An inductor exhibits an increased impedance with frequency, so can also be used to permit the passage of DC while attenuating AC.

    Two or three of these answers are quite long, I don't know if these explanations would be totally over the top, just right, or having insufficient detail for your son's assignment.
    Last edited: Oct 16, 2017
    Cannonball and Alec_t like this.
  8. Alec_t


    Jul 7, 2015
    If you check the online catalogue of any major electronics components distributor (such as Farnell, Digikey, Mouser, RadioSpares etc) you will see the various parameters/units used for selecting/characterising components.
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