Buffer opamp pinout question

[primalphunk]

I was planning on building a buffer board from Anderton's DIY Projects for Guitarists.  I'm using a TL071 and it seems like there may be a misprint in the book about just which pins to use.  In the earliest chapter in the book he says that on the 741 style chip no project in the book uses pins 1, 5 & 8.  Then in the chapter with the actual project (pg. 38) his schematic shows that pins 1, 2, 3, 4 & 7 are to be used.  I'm enough of a novice that I need help with this so I took a look at his 1976 article about a buffer board.  They look really similar but the 1976 version lists pins 2, 3, 4, 6 & 7 as the ones to use.  What gives?

[Robin]

I believe the TL071 and LM741 pinouts are the same - the 071 being a superior opamp, though. Pins 1 and 5 are for offset null to compensate for voltage variances at the inputs and pin 8 is dead and need not be connected, as I recall. Offset null is not often needed in capacitively coupled effects stuff and probably his reason for the comment that pins 1,5 and 8 wouldn't be used. All I have is a copy of Anderton's 1976 buffer article (wish I had a copy of the book) and it does show an input cap and no connection for 1,5 and 8. I built this and it does work fine.
There is a thread in the archives you may want to check out -- Re: Craig Anderton guitar buffer problems (dated 1/14/02). Sorry I don't have a quick link.
Check National Semiconductor's site for datasheets and application notes on these and other chips.

Rob

[smoguzbenjamin]

in ascii art:

Code Select Expand


TL071 pinout:

offset      1-\/-8 NC
inv in      2-  -7 V+
non inv in  3-  -6 out
ground      4----5 offset


[primalphunk]

Hmmm...In my first post a smiley appeared instead of the last bit of stuff that I had in ().  What I was trying to do was indicate that in the book this project is on page 38.  

Based upon the feedback that I have seen here so far, I am fairly certain now that when this item went to press that it was in fact a typo in the schematic.  Otherwise we are not using the output of the opamp at all.  I'm going to go ahead and substitute a 6 for the 1 that actually does appear in the symbol.  

Thanks for all the help so far.  If anyone reads this and knows I'm about to make a horrible mistake please fill me in.  Just say, "Hey man...if you do that you're gonna burn down your house or something!" :wink:

peace,
James