Xref: utzoo sci.electronics:5196 rec.audio:10915 rec.ham-radio:8731
Newsgroups: sci.electronics,rec.audio,rec.ham-radio
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: 60 Hz hum filter
Message-ID: <1989Feb17.172352.5088@utzoo.uucp>
Organization: U of Toronto Zoology
References: <2313@rayssdb.ray.com>
Date: Fri, 17 Feb 89 17:23:52 GMT

In article <2313@rayssdb.ray.com> iws@rayssdb.ray.com (Ihor W. Slabicky) writes:
>Can anyone send me a schematic or info on broadband noise filters
>that will filter out 60 Hz hum on the 120VAC line? ...

The 60 Hz "hum" on the AC line *is* the AC power.  There is no way to
filter it out; if you want to run your recorder on AC, there will have
to be 60 Hz AC going into the power supply.  What you need is filtering
*inside* your recorder, to keep that 60 Hz out of the signal-handling
sections.  It's quite possible that you simply have a poorly-designed
recorder.

The one fix that wouldn't involve digging into the guts of your recorder
would be to forget using the recorder's own AC power supply, get a
separate power supply that produces the same output voltage as the
batteries, and hook that up to the recorder as a replacement for the
batteries.  This isn't certain to fix the problem but it would probably
help.  Radio Snack carries plug-in "bricks" of various voltages that
might do the job, although you'll probably need a bit of soldering to
connect them in.
-- 
The Earth is our mother;       |     Henry Spencer at U of Toronto Zoology
our nine months are up.        | uunet!attcan!utzoo!henry henry@zoo.toronto.edu