Unused IC inputs

[patchell]

    You are probably right.  This is actually another demonstration of my bad
memory.  I checked another board I did a while back, what I did on that one was to
tie the plus input to ground (VCC/2) and the minus input to the output, making a
buffer.  Generally, I try to avoid un-committed opamps, only to discover later that
I need another opamp....then it is dead bug time.

Harry Bissell wrote:

> Watch out Jim... some op-amps do not like having both input pins tied together
> and or
> to the negative rail... I've seen hotplates made that way. Some one did that in
> one of our
> industrial controls just recently.  I like to make a voltage follower, with the
> non-inverting
> input at virtual ground (single supply) or actual ground (dual supply).
>

    All I can say is I can blame the medication I am on right now.......

>
> Think the hidden weenie is in the common mode voltage range....
>
> H^) harry
>
> patchell wrote:
>
> >     Unused outputs are easy...leave them unconnected.
> >
> >     Unused inputs....depends on what it is.  The 4049, the inputs need to be
> > tied to one supply rail or the other.  The TL072, I have left input pins
> > floating, but you probably should tie them to ground just to be safe.  Most
> > important thing is that both pins be tied to the same voltage.
> >
> > Justin Herrmann wrote:
> >
> > > Hello, list:
> > >
> > > I'm building some stompboxes that use two of the six inverters of a CMOS
> > > 4049 hex inverter chip <http://us.st.com/stonline/books/pdf/docs/2052.pdf>
> > > and one of the two op-amps in a TL072 jfet op-amp
> > > <http://sdremote1.njr.com/cdrom/index/ae/ae04010.pdf>.  My question is,
> > > what do I do with the unused inputs and outputs?  Would I be able to put
> > > them in parallel with the ones I am using?
> > >
> > >                                                 -Thanks-
> > >                                                 -Justin Herrmann-
> >
> > --
> >  -Jim
> > ------------------------------------------------
> > * Visit:http://www.silcom.com/~patchell/
> > *-----------------------------------------------
> > *If you didn't buy a home in Santa Barbara,
> > * You didn't pay enough!
> > ------------------------------------------------

--
 -Jim
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