Where to purchase operational amplifiers

Discussion in 'General Electronics Chat' started by hendro2k13, Dec 16, 2014.

  1. hendro2k13

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    Dec 16, 2014
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  2. hendro2k13

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    Dec 16, 2014
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    Also, what are the variations between op amps?
     
  3. Papabravo

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    Feb 24, 2006
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    You don't say where you are located and the answer kind of depends on that. In the US, there are electronics parts distributors that service the folks buy in bulk and manufacture electronics assemblies. There are also a handful of companies that sell small quantities to hobbyists and experimenters. I'm guessing you fall into the latter category.

    As for the second question, the answer is in the individual datasheets. The primary features you should look for are power supply requirements, gain, bandwitdth, input offset voltage, input bias current, slew rate, input impedance, output impedance, and packaging. Price should also be a factor but you have to ask the distributors for that.
     
    Last edited: Dec 16, 2014
  4. hendro2k13

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    Dec 16, 2014
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    I am in the US and I don't need that many necessarily. I just need to know which one to get as well because there are so many factors when purchasing. Such as, Amplifier type, output type, Slew rate Gain bandwidth Product, -3db Bandwidth, Current- Input bias and so on
     
  5. MrChips

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    Oct 2, 2009
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    There are some commonly used opamps for experimentation by hobbyists, e.g. LM324, LM358, just to name a couple.

    Do you have an electronics supply store in your town or city? I don't mean a store that sells computers, cell phones and/or TV and stereo equipment.

    Otherwise you may have to order from an online supplier.

    An instrumentation amplifier is a special kind of amplifier for special situations. It this quite likely that you do not need the instrumentation amplifier circuit shown in that tutorial.

    You have to tell us what you are trying to do.
     
  6. hendro2k13

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    Dec 16, 2014
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    I am simulating a heartbeat and the aortic pressure (Ao) signal is faint and needs to be amplified roughly x1000 times.
     
  7. MrChips

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    Ok. Good answer. Is this for a school project, commercial application or simply personal experimentation?
     
  8. hendro2k13

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    School project!
     
  9. MrChips

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    Good to know so we can put this in proper perspective.

    Yes, you will need an instrumentation amplifier for that application in order to achieve a high CMRR (common mode rejection ratio). You will need at least two stages of applification to achieve a gain of 1000. The first stage will be the in-amp and the following stage will be a standard opamp.

    You can create a 3-opamp instrumentation amplifier as shown in the tutorial using a low noise FET input amplifier such as an TL074. Or you can use a in-amp such as INA121.

    The single TL074 has four opamps in a single package and that could be used alone for a compact solution.

    You will need two 9V batteries to power your circuit.
     
  10. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    My go-to source for just a few to serious production quantities is Digi Key. They take small orders seriously, typically shipping same day as the order. And for really tiny orders (most of mine) you can get USPS shipping for about 3 bucks. Mouser and Newark are also good but I like the DK site the best as it is simple and fast, great for part mining and they link to data sheets.

    However, most of the really cool modern chips only come in surface mount packages. For these I get adaptor boards off EBay. They are really inexpensive from China but the free shipping takes 2-3 weeks for them to arrive. That is why I have a sizeable collection in advance of any need.
     
  11. hendro2k13

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    Dec 16, 2014
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    just some more specific things to add. I am using my laptop to power a box which is around 5V, I also need to add a dial which will the volts going through. The exact number is 7mV=1V
     
  12. hendro2k13

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    Dec 16, 2014
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    Correction: the dial is meant to change the Gain to fine tune
     
  13. wayneh

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    I like the sources already mentioned, but if I'm in a hurry there is always a nearby Radio Shack, and I believe they carry one or two op-amps in the store.
     
  14. MrChips

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    Radio Shack is currently in bankruptcy negotiations.
     
  15. hendro2k13

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    Dec 16, 2014
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    I'm not too good with this stuff but how do figure out what specific parts I need to build this thing?
     
  16. MrChips

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    That's the beauty about electronics and AAC. You learn and expand your knowledge by doing.
    Continue to ask questions and get help along the way. Share your experience with others.

    Life is a journey!
     
  17. bertus

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  18. wayneh

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    My local store is still open, for now.
     
  19. hendro2k13

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  20. MrChips

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    So you asked a question and we gave you the qualified answer. Now you question it?
    Google instrumentation amplifier.
     
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