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.

Thanks!

 

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?

 

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!
im1992

 

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.

 

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.

 

I am trying to use this tutorial:

Pace was too slow, he should have worn long sleeves (hair was very distracting)...