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The LM383 Story

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Re: The LM383 Story

#31

Post by sbradford26 »

paulgerhardt wrote: post #9
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…

HiFiBerry is a good place to start: https://www.hifiberry.com/build/guides/hifiberry-streamer-in...

I worked on almost the exact same idea for my senior design and the audio output from the dac built into the pi is terrible. The HiFiBerry board was a life saver.

Re: The LM383 Story

#32

Post by weinzierl »

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] Screenplays are usually written in Courier 12. 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.

Re: The LM383 Story

#33

Post by weinzierl »

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

You can pop LED's. Maybe not quite the same but also not as expensive.

Re: The LM383 Story

#34

Post by phkahler »

Load dump is not about connecting two batteries in series to achieve 24V. It'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.

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't start his bulldozer. He doesn't have jumper cables, but he's got an arc welder... I don't know if that actually happened but it would not surprise me.

Re: The LM383 Story

#35

Post by skykooler »

makomk wrote: post #25

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.

The paper from Chrysler is also fascinating. It's the first time I've seen "Side of a submarine" as an element in a circuit diagram.

Re: The LM383 Story

#36

Post by technofiend »

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…

Courier 12 is my go to for cutting and pasting terminal output because so much depends on fixed width fonts lining up properly and Outlook doesn't offer an exact match of xterm's 9x15 font.

Re: The LM383 Story

#37

Post by yitchelle »

squarefoot wrote: post #26
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:)

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

Re: The LM383 Story

#38

Post by linker3000 »

weinzierl wrote: post #33
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

You can pop LED's. Maybe not quite the same but also not as expensive.

Careful - many years ago one just missed my eye and cut my brow (unplanned overload; no dicking around involved)

Re: The LM383 Story

#39

Post by jjoonathan »

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 that p-type silicon has lower mobility and worse ohmic-junction performance than n-type silicon. A real semiconductor engineer should verify, but I believe the core of the dig is that the low performance acts like intrinsic protection: the PNPs simply couldn't conduct enough current to destroy themselves, at least not in the multitude of spectacular fashions as the NPNs.

Re: The LM383 Story

#40

Post by [deleted] »

phkahler wrote: post #34

Load dump is not about connecting two batteries in series to achieve 24V. It'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. On a related note, I heard this 2nd…

[deleted]
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