Unused IC inputs

[Magnus Danielson]

From: Justin Herrmann <herrmann at eecs.ukans.edu>
Subject: Unused IC inputs
Date: Sat, 29 Jul 2000 13:04:25 -0500 (CDT)

> 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?

For the 4049, hook the inputs to ground or Vcc and for the TL072 make a buffer
and wire the + input to ground. Naturally the buffer should possibly find its
place somewhere in the curcuit.

I recall in the back of my head that you migth consider hooking a resistor
from the powerline to an CMOS input, but I don't recall exactly why... it where
to avoid some trouble which I don't recall...

For the op-amp, put in a resistor or a jumper for the feedback loop of the
buffer, this will make it easier to convert it into something else when the
need arises.

Cheers,
Magnus