TL072 Opamp help

Started by coxter, August 24, 2006, 05:44:21 AM

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coxter

Hi, I'm really new to this so I just need a little guidience,

What does pin 4 and 8 do? I dont understand what Vcc means...
Thank you


Mihkel

Pin 4 should be ground
Pin 8 should be the positive power supply connection.

GibsonGM

How come pin 1 is listed as "offset null"? I didn't think the 72 had that available...am I high, isn't pin 1 just Output 1?? Hmmm.
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redeffect

Welcome to the wonderful world of misprinted information.

coxter

Oh yes, thank you all very much for the clarification. So is this the top view of the chip or the bottom (with the pins pointing at me) view?


Quote from: coxter on August 24, 2006, 05:44:21 AM
Hi, I'm really new to this so I just need a little guidience,

What does pin 4 and 8 do? I dont understand what Vcc means...
Thank you



Mihkel

Top view, pins pointing down.

markm

Quote from: redeffect on August 24, 2006, 10:24:59 AM
Welcome to the wonderful world of misprinted information.

I thought I was the only one that used misprinted datasheets  :icon_mad:

ashcat_lt

Quote from: Mihkel on August 24, 2006, 06:01:34 AM
Pin 4 should be ground
Pin 8 should be the positive power supply connection.

is that the "bias voltage" or something else?  In other words, how does this compare to a 3 pin transistor, or not at all?

R.G.

Quoteis that the "bias voltage" or something else?  In other words, how does this compare to a 3 pin transistor, or not at all?
Almost not at all.

An operational amplifier is an entire circuit inside, all on its own. A transistor has to have external things to make it do much.

The +vcc and ground pins are where the DC power is supplied to make things go. No power on the power pins = no go.

The input is where you place input and feedback signals, and the output is where signal comes out of for use and for feedback.

In opamps, "bias voltage" is the voltage where you tie the + input. This sets the DC voltage level on the output and - input by the feedback operation of the circuit.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

ashcat_lt

the reason I asked was that I think I've seen people recomend using this opamp (or half of it) in this circuit for Q1.  Q1 only has 3 leads...???

ashcat_lt

Is this question just too silly?  Anybody got a link to "op amp basics" or something along that line?

Stompin Tom

#13
God knows I ain't no expert, but doesn't that schematic on the datasheet (not in the above illustration) tell you what's going on inside the opamp? Anywho, if you look further down the AMZ buffer page you linked to, there's an opamp based buffer. Is that what you're refering to?

This datasheet, by the way, has the right pinout:

focus.ti.com/lit/ds/symlink/tl072.pdf