A shockingly basic question
hdan at charybdis.com
Thu Jun 26 21:13:50 CEST 1997
This is a shockingly basic question :-), but for some reason it
occurred to me the other night, and I couldn't answer it.
If you have a 1/4" jack input (2 conductor), the normal way to
hook it up to an opamp is to ground the sleeve, and then tie
the tip to the opamp in with a resistor. However, this causes
your module to share ground with the incoming signal, which
(I think) could cause a ground loop, especially if both devices
have ground pins on their power cords. Am I right so far?
Ok, here's the question: Assuming you're just doing something simple
(like buffering the signal), could you hook it up as follows:
| |\ |
TIP: --R1-|-|-\ |
| \_|___ Out
This would (I think) accurately buffer the signal (inverted, of course), but
without a ground connection between the two devices.
Am I right? Is this a pointless observation? Thanks for any responses.
I'm slightly embarassed, since I've been building modules for a little while
now, and I routinely redesign the schematics floating around to better match
my requirements. Oh well, the hazards of an informal education....
Dan Higdon (hdan at charybdis.com)
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