An early LM12 chipamp design

[jackinnj]

i came across this looking for an article in Radio Electronics (no longer published) --

http://www.tech-diy.com/earlychipampdesign.htm

 

[scooby300]

I think i`ve got some of these old chips around somewhere ? (just got to find them).


It would be nice to power then back up just to see if they work!.
Plus see if they sound any better or worse than the new lm chips (lm3875 , lm4780) .

 

[scooby300]

I think i`ve got some of these old chips around somewhere ? (just got to find them).


It would be nice to power then back up just to see if they work!.
Plus see if they sound any better or worse than the new lm chips (lm3875 , lm4780) .

 

[cm961]

I built a four channel LM12 amp. It sounded great. The transformer was undersized though, you could hear a compression type sound. Then the crossovers stopped working.

Pete

 

[carlosfm]

A portuguese diyer friend has made one, some time ago.

http://www.diyaudio.com/forums/showthread.php?s=&threadid=13811&highlight=

 

[Tekko]

I´d like to get two of these, 300 watts into 2 ohm if i paralell two.

Anyone got two to sell ?

 

[DC Dave]

I´d like to get two of these, 300 watts into 2 ohm if i paralell two.

Anyone got two to sell ?

Digikey still sells them. Not exactly cheap though, $20 per ic
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=159586&Row=338604&Site=US

Here's the datasheet from National.
http://cache.national.com/ds/LM/LM12CL.pdf

Could be a fun project for people looking to try a different chip.

 

[Tekko]

Nevermind. I found a better suited ic.

 

[XELB]

How does it sounds ?


If it sound great, I think this could be a nice OpAmp for a active subwoofer ( I guess... )

 

[jackinnj]

I am surprised that no-one has (apparently) seen that the article contains a schematic and PCB layout for a 12V switching power supply for the LM12.

 

[DigitalJunkie]

Wow,Digikey still has them?
I thought they were extinct..

Interesting..
I've seen quite a few different designs online (not that they differ a whole lot )
I think I've even seen a circuit for controlling large motors with them!

 

[jackinnj]

Wow,Digikey still has them?
I thought they were extinct..

Interesting..
I've seen quite a few different designs online (not that they differ a whole lot )
I think I've even seen a circuit for controlling large motors with them!

better off controlling motors with an H-Bridge -- since the transistors don't operate through the linear portion of the curve you don't dissipate that much heat -- both International Rectifier and National have some great ready-built H-Bridge chips.

LM12's show up on EBay every once in a while, as do the APEX high voltage opamps -- you just have to be looking (and I don't have the time.)