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From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: net.analog
Subject: Re: Can't get the LM383 to work
Message-ID: <744@kitty.UUCP>
Date: Thu, 23-Jan-86 10:03:44 EST
Article-I.D.: kitty.744
Posted: Thu Jan 23 10:03:44 1986
Date-Received: Sun, 26-Jan-86 05:34:43 EST
References: <2b6f01a2.1de6@apollo.uucp>
Organization: Recognition Research Corp., Clarence, NY
Lines: 27

> I recently needed about 5 watts of audio in a small space, so I went down
> to the local rat shack and bought a LM383.  It is supposed to put out
> 8 watts or so into a 4 ohm load.
> 
> I wired it up just like the little diagram on the back, but all it does
> is oscillate.  I played with the negative feedback a bit and even tried
> a new chip.  I re-did the layout to give more separation between input
> and output, and put in bigger bypass capacitors.  Nothing helped.  I
> looked up the chip in a National data book and it gives the same circuit
> as the one I got off the back of the rat shack package.
> 
> Does this chip work or not?  Has anyone tried it?  Is there some easier
> way to get 5 watts of audio?  Distortion up to about 1% is not a problem,
> and I have a split supply plus/minus 8 volts.

	The chip works.  The 0.2 uF bypass capacitors from V_s to ground
and V_output to ground should be tanatalum to present a good low impedance
path.  I suspect that you have used some inappropriate bypass capacitors.
A brute force large bypass capacitor is not the answer since a crappy 100 uF
aluminum electrolytic is not as good as a 0.2 uF tantalum.

==>  Larry Lippman @ Recognition Research Corp., Clarence, New York        <==
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