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I'd like to build a cheap and easy op-amp to use with my electric guitar.

The op-amp should input from the guitar's jack and output to a standard "earphone's cable" jack ( not sure about the jargon here ). So that I can plug it into my Hi-Fi's aux channel, or my PC, or just listen on my earphones. A 9v battery would be the preffered power source.

Where can I find schematics for a projet like this?

Also, If I wanted to extend the op-amp to handle basic effects, ( Distortion, Feedback, etc. ) How would I achieve that?

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    \$\begingroup\$ Why would you build your own op-amp when something like an LM324 is less than 20 cents in quantity? Unless you mean an amplifier based around an op-amp ... or am I missing something? \$\endgroup\$
    – Thomas O
    Commented Sep 29, 2010 at 20:09
  • \$\begingroup\$ I have no idea what a LM324 is, I don't now where I could buy that, but most importantly I'd like to learn... :) \$\endgroup\$
    – Stefan
    Commented Sep 29, 2010 at 20:13
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    \$\begingroup\$ First result on Google: national.com/mpf/LM/LM324.html Buy it from Newark: newark.com/jsp/search/… \$\endgroup\$
    – Thomas O
    Commented Sep 29, 2010 at 20:16

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Wow....there's so many choices out there, it can be hard to pick one!

A good place to start is with the Elliott Sound Products website, there's a heap of different amplifier designs for all manner of applications, and there's also different levels of difficulty too.

A great way to get started is to get a breadboard, buy all the stuff you need to make a simple looking amp, (there's a few single chip circuits on that link also) and just have a good experiment with it :)

You can do stuff with a 9V battery quite safely, just get some audio jacks soldered to some wires and you can hook up your guitar and stuff.

Distortion and feedback are a natural progression from amp design, you'll get into that quite quickly I'd imagine, it's not a big leap in complexity - it's normally just changing a few component values.

this site is also great, lots of great stuff for guitarists -> Beavis Audio

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  • \$\begingroup\$ No problem, not been on that Beavis Audio website in a while - I forgot how good it was, not only is it hilariously witty, the instructions and diagrams are fantastically clear too...fantastisch! \$\endgroup\$
    – Jim
    Commented Sep 29, 2010 at 20:36
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I don't think you want to build an op-amp. An op-amp is an electronic component that you usually buy already-made and build other things with. A typical op-amp IC looks like this:

This is an op-amp

I think what you want is to build a headphone/line amplifier with an op-amp. There's a popular guide here: http://tangentsoft.net/audio/cmoy-tutorial/

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    \$\begingroup\$ +1. Good op-amps are hard to design, and generally cheap to buy. I had to design a basic op-amp out of 2N3904 and 2N3906 transistors for a college class, and it was a pain! Not so much because of the linear region, but the nonlinear crap that happens near the supply rails. \$\endgroup\$
    – Jason S
    Commented Sep 29, 2010 at 23:51
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I'm guessing from the description, you are not looking to build an op-amp but rather an amp (ie without the op part)

you might start with something like the cmoy headphone amp. google for cmoy kit.

Some of the kits you find may or may not have a volume knob but once you have a gain that works, the stereo could adjust from there.

This would be a good starting project that is nice to have and it will also teach some of the basics.... like what an op-amp is.

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  • \$\begingroup\$ hehe... yes... I really don't know much about electronics... You've spotted that :) \$\endgroup\$
    – Stefan
    Commented Sep 29, 2010 at 20:24
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There is a project about a practice board in the General Guitar Gadgets website.

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