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The LM383 Story

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Re: The LM383 Story

#21

Post by amelius »

wpietri wrote: post #15

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.

Well, a computer is basically a handful of gates, instantiated millions of times. So you only have to optimize those basic gates, and because they are (supposed to be) small, the design-space is small as well which simplifies optimization.

The hard part is actually the parasitics that come into play (capacitive/inductive coupling between signal lines and the bulk), and dealing with that when synthesizing the design.

Re: The LM383 Story

#22

Post by Johnny555 »

pwaivers wrote: post #14

> "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." This first paragraph is almost gibberish to me. In a goo…

I don't do any analog work, so I wasn't familiar with the LM383 but it made perfect sense to me.

From the article, I knew the LM383 was a 5 lead audio amp. From context in the sentence it was clear that the TDA2002 is a predecessor of the LM383. I don't know who Bruno Murari or SGS are, but again, context makes it clear that Murari worked at SGS when he designed the TDA2002.

What part did you find to be gibberish?

Re: The LM383 Story

#23

Post by squarefoot »

aidos wrote: post #8

OT but it seems like a good place to ask: 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. Does a…

There are many projects of bluetooth amplified boxes using class-D modules including BT receivers. Searching for "diy bluetooth speaker box" on Google Images returns some interesting results. You just need then to find the suitable amplifier without BT and stick the RPi inside the box. A word of advice though: the Raspberries have a sub par audio output which isn't good for music, so you may want to consider either a different SBC or an external USB sound card, as even the cheapest will sound a lot better than the RPi on board one.

Re: The LM383 Story

#25

Post by makomk »

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.

Re: The LM383 Story

#26

Post by squarefoot »

wpietri wrote: post #15

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.

EE aside, keeping the magic smoke confined inside the components requires also some good witchcraft knowledge:)

Re: The LM383 Story

#27

Post by frabert »

nicolaslem wrote: post #6

I have great memories building small guitar amplifiers out of its little brother the LM386. 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" guitar speaker could make some serious rock'n'roll! I remember taking most design ideas from this gold mine: https://www.sonelec-musique.com/electron…

It's widely known ad the "noisy cricket" amp I believe :)

Re: The LM383 Story

#28

Post by JohnBooty »

aidos wrote: post #8

OT but it seems like a good place to ask: 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. Does a…

If you want a box with two tweeters and a woofer for some really legit sound, here's a design from a superstar of the DIY speaker design world:

https://sites.google.com/site/undefinition/isetta

He mostly just lays out the speaker and crossover design; but as he mentions a search for "TPA3116 2.1 amp" will give you lots of results on Amazon, AliExpress, and Parts Express.

PE's forums are good, lots of people have tackled similar projects:

http://techtalk.parts-express.com/forum

For anybody else interested in this hobby, there are lots of fantastic kits out there, primarily for bookshelf/tower speakers and subwoofers.

https://www.diysoundgroup.com

https://www.parts-express.com/cat/speaker-kits/286

The product page for the C-Notes (a fantastic value at $100/pair!) kit has a build video which gives you a great idea of the process and the tools you'll need. Process is similar for any flat-pack kit.

https://www.parts-express.com/c-note-mt-bookshelf-speaker-ki...

Of course you can also go as far down the DIY hole as you like, designing your own electronics and selecting drivers, etc.

Re: The LM383 Story

#29

Post by weinzierl »

This is a fantastic read. At the risk of being the guy that needs the joke explained, I can't make sense of following paragraph:

> 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.

The other components need protection anyway. What is the connection to the LM383?

> Some one made the joke that the lateral PNP's were so bad that even delco would not be able to destroy them.

Why are bad lateral PNP's hard to destroy? Is he talking about PNP's inside the LM383 or inside other power supply circuitry that's supposed to provide protection?

>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.

Re: The LM383 Story

#30

Post by sbradford26 »

amelius wrote: post #21
wpietri wrote: post #15

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.

Well, a computer is basically a handful of gates, instantiated millions of times. So you only have to optimize those basic gates, and because they are (supposed to be) small, the design-space is small as well which simplifies optimization. The hard part is actually the parasitics that come into play (capacitive/inductive coupling between signal lines and the bulk), and dealing with that when synthesizing the design.

Digital circuits also add the joys of clocks.
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