Ignorant op amp question

[ethrbunny]

Im building a switch box and want to buffer the inputs as some will be mixed and others will not. I have some extra TL074 and TL084 sitting about - can I use either of these as voltage followers?

I googled 'op amp voltage follower' and found all the essential schematics. But none specifically refer to JFET op amps. Is this because its obvious that you *can* or that you would *never* do this?

[toneman]

any opamp will work in the buffer or voltage-follower mode.
some have lower noise; some have more PS headroom;
some have more current drive capability;
some handle highter PS voltages;
but, electronically, if the pins match, it should/will work.
Stayamped
tone

[Paul Perry (Frostwave)]

When you say 'buffering', you could simplify things by just using fet source-followers as buffers, if you did not need any gain.
But if you are wanting to use op amps as unity gain buffers, the only thing to worry about is if they are stable at unity gain.
Almost all are.

[ethrbunny]

I was originally going to use 2n2222 (I think) but kept running into posts talking about the virtues of op amp followers. For unity gain (is that the correct term?) (IE I just want a follower - not an amplifier) can I use either method?

[Transmogrifox]

I tend to think op amps are the way to go for buffers.  At unity gain (voltage follower), the noise specs on many op amps are as good, or even exceed that of a JFET source follower.  In addition, you get closer to true unity gain out of op amps, but JFET source followers do attenuate a little.  With op amps, you can drive the input with much higher amplitude signals without increasing harmonic distortion much.  With JFET source followers (or even BJT followers), anything much over 100 mV starts to suffer from the "low-fi" effect, and deviates significantly from the small signal linear approximation at around 1 Volt (amplitude).

I used to think BJT's and FETS were the way to go for buffers since they are smaller and take up less circuit board real estate, but when I started looking at higher amplitude output waveforms, I began to see quite a bit of "rounding".  Harmonic distortion is pretty bad when you can actually see it on a scope.

In addition, op amps are particularly handy when mixing multiple inputs.

[ethrbunny]

In addition, op amps are particularly handy when mixing multiple inputs.

The plan was to have a 'mix' channel in addition to the two solo inputs.

[ignorance value='high']Do I need to buffer the outputs in addition to the inputs? Or just one or the other?[/ignorance]