The LM383 Story

Load dump is not about connecting two batteries in series to achieve 24V. It&#x27;s about (accidentally?) disconnecting the battery while charging from the alternator - which is an inductive source. When the load taking the current is disconnected that current is going to continue flowing through the vehicle electrical system which will cause a voltage spike until the current goes down.<p>On a related note, I heard this 2nd hand from a guy who was talking to CAT about a module they wanted to have 80V over voltage protection for a crazy amount of time (minutes). My friend asked what scenario required that and it was something like this: Guy at a construction site can&#x27;t start his bulldozer. He doesn&#x27;t have jumper cables, but he&#x27;s got an arc welder... I don&#x27;t know if that actually happened but it would not surprise me.

I have great memories building small guitar amplifiers out of its little brother the LM386.<p>Adding just a transistor to handle the high impedance of the guitar and a few cents worth of resistors and capacitors, one could build a tiny amplifier that once plugged to a 12&quot; guitar speaker could make some serious rock&#x27;n&#x27;roll!<p>I remember taking most design ideas from this gold mine: <a href="https:&#x2F;&#x2F;www.sonelec-musique.com&#x2F;electronique_realisations.html" rel="nofollow">https:&#x2F;&#x2F;www.sonelec-musique.com&#x2F;electronique_realisations.ht...</a> (unfortunately only in French)

This is a fantastic read. At the risk of being the guy that needs the joke explained, I can&#x27;t make sense of following paragraph:<p>&gt; <i>While the -6 volt supply spec caused little trouble for the LM383, it meant that all the other electronics in a car needed to voltage regulator that could provide protection.</i><p>The other components need protection anyway. What is the connection to the LM383?<p>&gt; <i>Some one made the joke that the lateral PNP&#x27;s were so bad that even delco would not be able to destroy them.</i><p>Why are bad lateral PNP&#x27;s hard to destroy? Is he talking about PNP&#x27;s inside the LM383 or inside other power supply circuitry that&#x27;s supposed to provide protection?<p>&gt;<i>A skunk works layout of a lateral PNP regulator ultimately made its way to delco. And sure enough, they could not destroy it. They loved it. And National Semiconductor got into the business of making PNP output regulators.</i>

When I read things like this it amazes me that computers work at all. As person who spends 99% of the time working on software, I so much take all of the EE level for granted.

So the new LM386 is the Nsiway NS8002. This chip is better in that the output capacitor it not required (it has two LM386s making an h-bridge). On lcsc.com, they are $0.0329 each for QTY=10, or $0.90 for boards (each) on eBay. They are nice if you don&#x27;t want to deal with class-D switching noise.<p>Cheap clock radios use them. They also use an 8-pin AM&#x2F;FM digital radio IC: pins for 32 KHz crystal, I2C, antenna (loopstick for AM), and audio out. No coils, inductors or filters needed.

&quot;My neighbor had just got a dog that was always barking. So I got tweeter, built up a simple 30kHz oscillator using a LM324. Set the two LM383 to swing rail to rail. Got a lantern battery that could put out the power. Then connected the tweeter.&quot;<p>Paging Steve Gibson: somebody reinvented your dog silencer[1][2]!<p>[1] <a href="https:&#x2F;&#x2F;www.grc.com&#x2F;tqc&#x2F;TheQuietCanine.htm" rel="nofollow">https:&#x2F;&#x2F;www.grc.com&#x2F;tqc&#x2F;TheQuietCanine.htm</a><p>[2] <a href="https:&#x2F;&#x2F;groups.google.com&#x2F;forum&#x2F;#!topic&#x2F;portable-sound-blaster&#x2F;4LI77KQM6xw" rel="nofollow">https:&#x2F;&#x2F;groups.google.com&#x2F;forum&#x2F;#!topic&#x2F;portable-sound-blast...</a>

I love the part about how Chrysler somehow managed to defeat the thermal protection and destroy the chip via a heatsink that had just the right amount of thermal resistance to cause the transistor to heat up above its safe operating area and cook itself whilst keeping the thermal protection circuit cool enough not to trip.

Fans of this article will also enjoy Ken Sherriff&#x27;s talk at Supercon last week: <a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=TKi1xX7KKOI" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=TKi1xX7KKOI</a>

I love the design (or lack thereof) of this site. Courier font plus the old scans of photocopies make it feel like i&#x27;m reading an old xeroxed white paper (in a good way).

&quot;Either 45Watts to one or 90watts to both appears to pop the plastic off the silicon with out any apparent damage to the chip&quot;<p>Oooh, found my project for the weekend!<p>&quot;Now it is no longer possible to do this since the packaging department had redesigned the package&quot;<p>aww shucks

OT but it seems like a good place to ask:<p>this week I’ve been looking into making a wireless speaker similar to a Sonos play:1. In terms of the streaming mechanism is was going to use a raspberry pi running as a snapclient, wired to a class-d amp board and a, say, 3” driver. I thought I would find a load of projects using a pi + amp + driver in a small box combination, but I must be looking in the wrong place.<p>Does anyone have any top tips of examples of setting something like this up? What amp &#x2F; driver combination to use? I’m not looking for anything amazing, and I’m sure round 1 will be a learning experience, but any help appreciated.

ha! make sure you read the last paragraph

As a kid, the LM383 had particular appeal: it was the highest-power amp chip available that ran off a &#x27;safe&#x27; voltage. I didn&#x27;t need to do any mains wiring.

&gt; <i>&quot;But it is humorous when the TDA2002 is often referred to as a replacement for the LM383. As a matter of fact, the LM383 is really a reverse engineering of the TDA2002. Credit should be given to the design engineer Bruno Murari who was working for SGS at the time. He was the one who came up with a way to do an automotive power amplifier using only five pins.&quot;</i><p>This first paragraph is almost gibberish to me. In a good way. I just find it humorous that there are so many in-the-know words here.