Op Amp Question

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If there is a diagram with an op amp in it, but no explicit connections to pins 4 and 7, are those understood to be connected up to - and + respectively?

TIA

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If it's an 8 pin op amp then probably... :)

I can't think of any 8 pin, single op amp ICs (741, TL081 etc) that isn't 4 = -ve, 7 = +ve.

What chip are you talking about specifically?

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That is the convention but remember it depends on which opamp - it's true for a 741 but not for a TL072 or LF311 which use pin 8 for V+

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ok, check this out:

Image

i figure the connections are -2 and +3, correct? would additional connections to 7/4 or 8/4 be implied and not necessarily explicitly stated?

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it's a 'UA741CN'

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Correct about the inputs and, yes, 4/7 for -V/+V on the 741 would be implied

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ok, so even though a drawing like this doesn't say so, you always want to hook up some power to the 7/4 8/4?

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Yep, have a gander at something like this and it'll give you the basics of how these things work

http://www.circuitstoday.com/introducti ... 741-op-amp

Do you have a particular build in mind?

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i'm looking to wire a few drive/distortion circuits together, give each a potentiometer with filters and such.

i've already put something together and the signal flow is there, but the drive/distortion is not. it actually began as a single transistor circuit, which seemed to have ever-so-little drive, and then another single transistor stage, and then an op amp stage... and as each stage were added, it actually seemed to lose any drive it had, rather than increase.

it's probably that the resistor and cap values are kind of random and outside the drawing specs, which i'm going to attempt to remedy with nos parts which will be a) much closer to spec, and b) should arrive soon.

what do you think of something like 3 or 4 op amp circuits in serial?

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Often single transistor circuits work as boosters rather than distortions but if you're looking for a very simple distortion have a look at a Bazz Fuss - great starter design with half a dozen components. For something more fuzzy look at Electra schematics. A few of Nick Greer's pedals are, erm, very closely related to the Electra

Cascaded opamps are fine for distortion but can take a bit of debugging if you're building from scratch. If you want a well known (and documented) opamp design have a look at an Big Muff V4 schematic.

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