Multi-stage Buffer TL072

[pat5s]

Hey guys this is the first time i posting and i just want to ask some question.

1. Can you series connection dual op amp? Like out A goes to input B (don't know which one) and then use the out B?

2. If yes, you can, then can i build something like multi stage inverting buffer? The first stage just inverting unity gain(-1) buffer and the second  stage is also inverting unity gain(-1) buffer, so if i want to invert the phase, it's just a flip of a switch.

My plan is using TL072 with Vr on pin 3 and Input on pin 2. Then output A pin 1 goes to pin 6, but i don't know the rest of the circuit is.

3. If (question 1) no, you can't, then will i have better success with 2 single op amp like TL071?

That's all! Thank you for the attention...

[EBK]

Hey guys this is the first time i posting and i just want to ask some question.

1. Can you series connection dual op amp? Like out A goes to input B (don't know which one) and then use the out B?

2. If yes, you can, then can i build something like multi stage inverting buffer? The first stage just inverting unity gain(-1) buffer and the second  stage is also inverting unity gain(-1) buffer, so if i want to invert the phase, it's just a flip of a switch.

My plan is using TL072 with Vr on pin 3 and Input on pin 2. Then output A pin 1 goes to pin 6, but i don't know the rest of the circuit is.

3. If (question 1) no, you can't, then will i have better success with 2 single op amp like TL071?

That's all! Thank you for the attention...

Welcome to the forum!

1. Yes.
2. Yes, but you'd be generally better off with a non-inverting buffer going into an optional inverting stage.  Higher input impedance.  You could actually do a phase inversion switch with a single op amp if you want, but I don't have a link for that handy.... 
3. Identical results.

[antonis]

As Eric said, it's better to form a non-inverting buffer with optional choice of inverting one, not only for input impedance purpose but also for possible "inaccuracy" of Rf/Rg = 1..
(you may result in signal amplification or attenuation..)

There is a way to invert a signal without need of accurate resistors (flying capacitor method) but it's fairly complex so the use of fine accuracy and stability resistors is more than acceptable down to ppm level..

One other possible way (I never used it.. ) is the use of specialized op-amps that have differential outputs (+ & -) and connect the possitive output up as a voltage follower so the negative outpout should be equally negative..

But everything depends on "how much signal unity" you want...

[EBK]

I knew R.G. had this laying around somewhere!
http://www.geofex.com/article_folders/polarity_reverser/polarity_reverser.htm

[PRR]

> phase inversion switch with a single op amp

Yes, but that gives a input impedance different in each condition. Infinity one way, R/2 the other way.



Because "R" should be higher than 200K for low guitar loading, but lower than 100K for good hiss performance on guitar signal, it's a real compromise.

As an internal stage (you know what drives it won't be affected) it works sweet.

Facing the guitar (how a "buffer" is sometimes used), I'd throw the extra 39 cents and front it with a NI buffer.

[pat5s]

Wow thank you so much for the answers!

Well i guess i will go as Mr. EBK said with non-inverting first and then selectable inverting buffer.

Thank you guys for the response! Now all i need just a circuit! 

[pat5s]

1. Well the first stage must be non-inverting buffer and then the Vout goes to the inverting input of second (inverting) stage, right?

2. Have any ideas for feedback resistor and ground resistor? (non-inverting)

3. Do you need input resistor for inverting Vin? What does it do?

4. To put it in "stompbox", i still need pull down R, coupling cap and make the Vr, right? Just making sure.

Thanks!