LM386 and ground positive

[smile44]

Hi,

I've been lurking here for a long time, and I have a (probably dumb) question about the use of a LM386.
Please be gentle, as I know next to nothing in electronics...

For some reasons (too long to explain !), I need to amplify a signal in a ground-positive circuit, and I'd like to use a LM386 for that purpose. The circuit I'd like to use is this (can't remember where I found it) :



and I would like to modify it to look like this :



Basically, I would invert pin 2 and pin 3, and also revert all the electrolytic caps.

Is it possible to use a LM386 in a ground-positive circuit ?
Would my modifications be correct ? If the LM386 can't be used in a ground-positive circuit, would there be any other alternative ?
Help much appreciated !

[owenjames]

pretty sure that the LM386 cant have a positve ground datasheet, doesn't seem to quote any negative supply voltages. There might be an alternate chip though.

[earthtonesaudio]

If you build it as shown in the second drawing, it's likely you will let the smoke out of the chip.  First, you have the power pins backwards.  The power pin (6) should go to the more positive (+) supply rail and the GND pin (4) should go to the more negative rail.  Second, the inputs should not be connected to a positive rail.  Either keep the inputs on the more negative supply rail, or capacitively couple them (a cap to ground on the unused input is a perfectly fine way to terminate it).

But, like owenjames said, the datasheet is pretty quiet about alternative supply voltage configurations.  There might be a good reason for that.

[smile44]

thanks for your answers.

But, like owenjames said, the datasheet is pretty quiet about alternative supply voltage configurations.  There might be a good reason for that.

So, I guess it is not possible to have a +ve ground with a LM386 ?

Is there a possible replacement for the LM386, that could do the trick ?

Thanks again !

[owenjames]

See if you can find a LME49725. Thats an audio power amp chip , that can have supply voltages from -18V to -4.5V and 4.5V to 18V. I could only find a surface mount version of it though. If your in US you might find a through hole one, if your making your own PCB surface mount shouldn't matter though, just a little more fiddly.

[smile44]

Thanks a lot indeed ! Looks like it is what I need ! I will try that.

[bool]

LME49725 is an OPAMP from National's "excellence" series. It has absolutely NOTHING in common with an audio power-amp.