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The LM383 Story

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Re: The LM383 Story

#51

Post by mbell »

jjoonathan wrote: post #39
weinzierl wrote: post #29

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 th…

I think the -6V connection was simply that the LM383 designers were able to trivially integrate something the automotive industry considered non-trivial due to historical reliance on discrete processes and "build it sturdy" engineering. Nowadays chips are so highly integrated, so cheap, and so ubiquitous that it's hard to imagine dealing with messy power any other way, but it wasn't always so. I have vague intuition…

Electrons are the majority charge carriers for NPN vs holes in PNP which does mean that NPN transistors are faster, they also are usually a _bit_ better than PNP in other specs (beta, etc).

However I don't think this was the main part of the joke, rather it's that lateral transistors are _way_ worse in pretty much every conceivable metric than vertical transistors save two - they are hard to destroy and cheap. So add 'lateral' to 'PNP' and you basically have 'worst possible transistor', so bad that you can't kill it.

Re: The LM383 Story

#52

Post by jjoonathan »

mbell wrote: post #51
jjoonathan wrote: post #39

Earlier quoted context omitted.

I think the -6V connection was simply that the LM383 designers were able to trivially integrate something the automotive industry considered non-trivial due to historical reliance on discrete processes and "build it sturdy" engineering. Nowadays chips are so highly integrated, so cheap, and so ubiquitous that it's hard to imagine dealing with messy power any other way, but it wasn't always so. I have vague intuition…

Electrons are the majority charge carriers for NPN vs holes in PNP which does mean that NPN transistors are faster, they also are usually a _bit_ better than PNP in other specs (beta, etc). However I don't think this was the main part of the joke, rather it's that lateral transistors are _way_ worse in pretty much every conceivable metric than vertical transistors save two - they are hard to destroy and cheap. So add…

Thanks for clarifying. I chalked up the difference between 'a bit' and 'can't kill it' to mitigations that have happened since the LM383 was designed but now that I'm reading up on lateral transistors it looks like you're almost certainly right.

Re: The LM383 Story

#53

Post by voltagex_ »

jhallenworld wrote: post #45

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't want to deal with class-D switching noise. Cheap clock radios use them. They also use an 8-pin AM/FM digital radio IC: pins for 32 KHz crystal, I2C, antenna (loopstic…

I wonder if I can get my hands on the radio IC - I'd love to do an "overkill breadboard" radio - connected up to a bluetooth transmitter or USB microphone so I could have it dump into a Raspberry Pi for LAN streaming.

Re: The LM383 Story

#54

Post by voltagex_ »

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…

I wish I had half a million bucks to dump into Snapclient - it's so close to being good, but needs some automated way to get the multi-speaker delay down to a good level.

In regards to your project - it depends how many sub-projects you want to spawn. I've got https://www.ebay.com.au/sch/i.html?_from=R40&_trksid=m570.l1... hooked up to my PC and some old speakers - 3.5mm jack, USB DAC and Bluetooth support. It's variable voltage up to 12V (I think). Funnily, if you supply it with 5~7 volts, you'll get a "low battery" audio cue - despite there being no battery connector anywhere.

The newer version of this has the volume knob in a silly place.

Re: The LM383 Story

#55

Post by starbeast »

weinzierl wrote: post #32
gnarbarian wrote: post #3

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

I like it as well and find it delightfully easy on the eyes. Funny thing is that I remember that back in the day I hated those Courier-font-style publications. They always seemed hard to read compared to well type-set documents. And I never understood screenplay writers obsession with Courier 12[1]. I guess the web is so noisy and cluttered today, that even harsh black Courier on a white page is a relief. [1] Screenp…

>I only know that because I sometimes read screenplays, for movies that interest me. It's fun and doesn't take as much time as it does to watch the movie.

I don't know why I find this as hilarious as I do, but thanks for sharing.

Personally, I haven't read many screenplays, though I did read the original one for Monty Python and the Holy Grail and it bears very little resemblance to the final film. There's a whole section about buying pet ants from Harrods.

Re: The LM383 Story

#56

Post by weinzierl »

starbeast wrote: post #55
weinzierl wrote: post #32

Earlier quoted context omitted.

I like it as well and find it delightfully easy on the eyes. Funny thing is that I remember that back in the day I hated those Courier-font-style publications. They always seemed hard to read compared to well type-set documents. And I never understood screenplay writers obsession with Courier 12[1]. I guess the web is so noisy and cluttered today, that even harsh black Courier on a white page is a relief. [1] Screenp…

>I only know that because I sometimes read screenplays, for movies that interest me. It's fun and doesn't take as much time as it does to watch the movie. I don't know why I find this as hilarious as I do, but thanks for sharing. Personally, I haven't read many screenplays, though I did read the original one for Monty Python and the Holy Grail and it bears very little resemblance to the final film. There's a whole se…

It wasn't in the Holy Grail, as far as I remember, but they actually did that sketch:

https://www.youtube.com/watch?v=nmKped3yARQ

Re: The LM383 Story

#57

Post by Dylan16807 »

anyfoo wrote: post #17
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…

Please don't be proud of ignorance. TDA200 and LM383 are obviously product or device names. Bruno Murari is obviously a person's name (a design engineer, as the sentence points out!), SGS is obviously a place where one works, likely a company. You should have no issues with the term "reverse engineering" if you are on Hacker News. So that only leaves "automotive power amplifier using only five pins". You probably kno…

Or to put it another way:

These are names of things. The sentence structure makes that clear, and makes it clear how they relate. They are not "in-the-know" terms that are lacking definitions. It is not gibberish, just like the sentence "Jane gave Sue a letter from Bob" is not gibberish, even though nobody defined "Jane", "Sue", or "Bob".

Re: The LM383 Story

#58

Post by setquk »

yitchelle wrote: post #37
squarefoot wrote: post #26

Earlier quoted context omitted.

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

The real crazy stuff is RF electronics. That stuff is voodoo.

It’s not really. People like everyone to think it is.

The difference is the building blocks of circuits are different due to function and most of the time you are interested in power transfer (which requires different impedance matching relationship).

Re: The LM383 Story

#59

Post by setquk »

cellularmitosis wrote: post #5

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

International Rectifier / Vishay IRF510’s do this. I know from experience building RF amps with them.

Wear safety glasses!

Re: The LM383 Story

#60

Post by setquk »

jhallenworld wrote: post #45

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't want to deal with class-D switching noise. Cheap clock radios use them. They also use an 8-pin AM/FM digital radio IC: pins for 32 KHz crystal, I2C, antenna (loopstic…

10% THD though. Ugh.
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