Which devices are operational-amplifiers (op-amps) found in?

Discussion in 'General Electronics Chat' started by im1992, Feb 7, 2016.

  1. im1992

    Thread Starter New Member

    Feb 7, 2016
    Hi all,

    So I want to make a pre-amp for a mic and need an op-amp IC. I have ordered a few different op-amps but am having trouble waiting (yes, I'm that impatient). So...what devices around the house have an op-amp in them? I want to know so I can tear-down something that's broken around the house and play with the op-amp IC before my parts arrive.

  2. paulktreg

    Distinguished Member

    Jun 2, 2008
    TV's and audio equipment will no doubt have op-amps but you don't want to be ripping those apart do you?

    Got any old/faulty PC sound cards?
  3. im1992

    Thread Starter New Member

    Feb 7, 2016
    Hello again!

    Thank you!! I found an LMV358 on an old non-functional motherboard. Since it was in a SOIC8 package, I de-soldered it and have soldered it on a board that effectively converts it to DIP8.

    I am trying to use this tutorial:

    At the 0:13 mark, it has a parts list.

    A few questions:
    1. Can the parts list be used as is even though the tutorial is for the LM358 and the one I have on hand is an LMV358? (I do know I must use power around 5v rather than something larger that the LM358 supports).
    2. Can I use something other than the potentiometer? Such as a fixed resistor? What value would be a good starting point?
    3. Tutorials such as the one I have listed above: do these capacitor/resistor values have to be followed or is there some ratio in circuit design one must follow? For example, for C2, can I go ahead and use a 47uF cap rather than a 4.7uF?

    Thank you!
  4. Jony130

    AAC Fanatic!

    Feb 17, 2009
    You have chosen poorly (bad design).
    1) You can use 5.5V max
    2) Yes, you can use 100kΩ. R5/R2 ratio sets the pre-amp gain.
    3) You can almost always put a large cap, and in this type of a circuit resistors value are not so critical, so you can experiment.
  5. im1992

    Thread Starter New Member

    Feb 7, 2016
    Thank you Jony! I appreciate the quick and concise answer. Apologies for the noob questions, I've never done anything like this before.

    I will do as you suggested and report back.

    As far as choice is concerned, is TDA2822M a good choice for my application? If no, can you suggest a good op-amp or other IC?

    Thank you very very much for taking the time to answer my questions.
  6. dl324

    Distinguished Member

    Mar 30, 2015
    Pace was too slow, he should have worn long sleeves (hair was very distracting)...
    Last edited: Feb 8, 2016