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Thread: Practical Experiment in LRC circuits

  1. #21
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    simulation has a big advantage
    safety and liability
    The difference between genius and stupidity is that genius has its limits.

  2. #22
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    Quote Originally Posted by jumper View Post
    I used multisims in college, it is great.

    Hundreds of discrete parts, IC chips, meters, supplies, etc.

    You download a free demo and get a student version for 42 dollars.

    Well worth it.

    http://www.ni.com/multisim/
    +1
    Most of my courses use this. Great software that models not only circuit conditions, but real life devices.
    There is also a MyDAQ hardware module that interfaces to the software. Through this you can breadboard, connect measurement devices, etc.

    Sent from my HTC6545LVW using Tapatalk

  3. #23
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    Quote Originally Posted by Shaneyj View Post
    +1
    Most of my courses use this. Great software that models not only circuit conditions, but real life devices.
    There is also a MyDAQ hardware module that interfaces to the software. Through this you can breadboard, connect measurement devices, etc.

    Sent from my HTC6545LVW using Tapatalk
    Commsims is another good one also.
    "Electricity is really just organized lightning." George Carlin


    Derek

  4. #24
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    Gents,
    Thanks for the input. GAR and Junkhound gave me some ideas on what I can do for in class experiments. I teach 3rd year electrical for an apprenticeship. We cover electrical components, inductors, capacitors and resistors, as well as motors and transformers.

    I wanted some in class exercises that we can do to show what happens on an electrical circuit when we have inductance or capacitance or a combination of both. One thing that I am missing is an oscope. I don't have access to one. So looking for simple experiments that we can perform in class.

    Thanks to all!

  5. #25
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    Quote Originally Posted by Fishn sparky View Post
    Gents,
    Thanks for the input. GAR and Junkhound gave me some ideas on what I can do for in class experiments. I teach 3rd year electrical for an apprenticeship. We cover electrical components, inductors, capacitors and resistors, as well as motors and transformers.

    I wanted some in class exercises that we can do to show what happens on an electrical circuit when we have inductance or capacitance or a combination of both. One thing that I am missing is an oscope. I don't have access to one. So looking for simple experiments that we can perform in class.

    Thanks to all!
    Not my usual area of operation, but I understand there are black box products out there that pass the info to your laptop for review/storage. Many others here likely to help you on that.

  6. #26
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    here's the rub (obviously)
    you can't 'see' electricity
    it acts imperceptibly fast
    pf and reactive power/power relationships are difficult to measure and illustrate
    The difference between genius and stupidity is that genius has its limits.

  7. #27
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    Quote Originally Posted by Ingenieur View Post
    here's the rub (obviously)
    you can't 'see' electricity
    it acts imperceptibly fast
    pf and reactive power/power relationships are difficult to measure and illustrate
    Without an oscope you can still at least get, for example, the current in a series (current measuring shunt) resistor for the L, the C and the whole circuit for parallel resonant, etc.
    You can then at least calculate what the relative phase angles must be for those values to coexist.

  8. #28
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    Quote Originally Posted by GoldDigger View Post
    Without an oscope you can still at least get, for example, the current in a series (current measuring shunt) resistor for the L, the C and the whole circuit for parallel resonant, etc.
    You can then at least calculate what the relative phase angles must be for those values to coexist.
    difficult
    not impossible
    we have no idea of the level of student or instruction
    but if you know L, C and R you need not measure anything

    you could measure the v across each (use an R to limit current)
    measure loop series i
    i between elements
    calc Z for each
    make changes and see impact

    but I have no idea what he is trying to illustrate that can't be done with a diagram and math
    The difference between genius and stupidity is that genius has its limits.

  9. #29
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    Quote Originally Posted by Ingenieur View Post
    difficult
    not impossible
    we have no idea of the level of student or instruction
    but if you know L, C and R you need not measure anything

    you could measure the v across each (use an R to limit current)
    measure loop series i
    i between elements
    calc Z for each
    make changes and see impact

    but I have no idea what he is trying to illustrate that can't be done with a diagram and math

    Some people just do not believe math, I guess.

    Or, more to the point, they do not remember it as well as hands on experience.

  10. #30
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    This does not count as 'practical everyday', but these were real components that let us see what was going on:

    Back in college physics they had a set of demos, using a couple of very large inductors and capacitors, a simpson 'display' analog meter, and a few other bits and pieces, such as lamps and such.

    The capacitor and resistor were selected to be large enough to have a time constant of a couple of seconds, and you could see the meter slowly rising and coming to equilibrium when voltage was applied. You could certainly do this with a modern digital meter, a large capacitor and a suitable resistor. A large enough inductor is not going to be easy, although you might be able to simulate a large inductor with an op-amp circuit.

    Another demo was a parallel LC circuit, with a lamp in the AC supply to the circuit and another lamp in series with the capacitor. The circulating current in the resonant part caused one lamp to be very bright; the other lamp in the supply was quite dim.

    They used a very large electromagnet as another inductor, and drew huge arcs across a knife switch when opening the supply, as the inductance tried to maintain the current flow.

    You might also consider doing demos with mechanical analogs of the components, eg. springs and flywheels.

    Hope this helps

    -Jon

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