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Electronic Design component selection intuition

  1. May 9, 2016 #1
    Hey,
    So I've taken a course learning theory to mosfets, Jfets, transistors etc. Recently we did an amplifier project with a summing component as a final project. I chose which component pretty randomly.
    I'm a little misled as to which component is better in certain circumstances. BJT's are higher current devices, this I know. Mosfet's have the perk of the enhancement region. I'm just curious what goes into the selection when faced with a design proposition.

    I suppose there are also just the applications of switching, amplification etc.


    as a second to my previous question, how after you select a component would you determine which bias configuration you would use? I know voltage divider circuits are most common, but is there specific times others are used? The only difference I see is trying to keep the number of required sources down.
     
  2. jcsd
  3. May 9, 2016 #2

    Baluncore

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    You would read design literature for several years and so understand the current technology and trends. If there was then no obvious way to solve the design problem, you would do several preliminary designs, each with different versions of the circuit with different components. You might ask for help on PF. One design will go together more easily and meet the specifications for less cost. That is the one you will probably use. It will come down to meeting the specifications, reliability and cost. After many years you will "recognise" the obvious solution without having to think about it. Always question the specifications you are given.

    The individual components do no exist in isolation. Each module is seen by a designer as a particular circuit topology. So the initial choice will probably not be so much the type of component as the topology. For example a buffer amplifier can be based on a BJT emitter follower, a MOSFET source follower or an op-amp follower. Each has advantages and disadvantages. By using the optimum bias, the component specification may be reduced which may then reduce the cost and increase the availability of the component part.
     
  4. May 12, 2016 #3

    Thanks baluncore,
    That seems to make sense, and be very obvious . In my electronics program I'm learning about all these components and then deciding on little things I can build to apply this knowledge. To help I purchased a few component kits and now have a healthy handful of different kinds of each component. Every time I start and decide which to use I feel this overwhelming "I don't know? This one?" And then I go with it and it works and it's fine. But I can't help but wonder, I know having 0 intuition isn't the right way.
     
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