The datasheet of LM386 says that it is 1 Watt audio amplifier. Does that mean that if I do P=IV on a speaker (voltage and current across speaker), it will give a P = 1 Watt?
Yes, 1 Watt, 2.83 Volts RMS across an Eight Ohm load .
Take note of how efficient whatever loudspeaker you run this amp thru.
Most loudspeakers will have an SPL (sound pressure level) rating, typically these ratings are (Not surprisingly, one Watt) widely variable from a whisper quiet of 82 DB, thru a nice sounding 92Db, up to a downright loud 99Db & higher!.
_________________________________________________Rick.......
Take note of how efficient whatever loudspeaker you run this amp thru.
Most loudspeakers will have an SPL (sound pressure level) rating, typically these ratings are (Not surprisingly, one Watt) widely variable from a whisper quiet of 82 DB, thru a nice sounding 92Db, up to a downright loud 99Db & higher!.
_________________________________________________Rick.......
The lm386 is intended as a headphone amplifier.
It was not designed to drive high current into loudspeaker type loads.
It was not designed to drive high current into loudspeaker type loads.
But it works quite fine when driving little loudspeakers (well...not so little... about 4 inches). So it can be used to build "small active loudspeakers" to be driven by a MP3 or that kind of thingies...but the LM386 cannot be taken near its limits or it will get into
Does anyone know if the capacitors used in the Datasheet of LM386 are electrolytic or not? The schematic shows non-electrolytic. Will this make any different? How?
Should the bypass cap be non-electrolytic as well?
http://www.ti.com/lit/ds/snas545a/snas545a.pdf (Page 6)
Should the bypass cap be non-electrolytic as well?
http://www.ti.com/lit/ds/snas545a/snas545a.pdf (Page 6)
The schematic on Page 6...with the gain of twenty, ..the one with just a pair of caps, the 250uF is an Electrolytic, note the polarization markings, make the voltage rating above your Vss(Supply voltage), the 0.05uF is indeed a 'disc' cap, non-polarized, more than likely it is rated at 50V, well within your supply voltage. Very small & inexpensive parts.
_____________________________________________Rick...........
_____________________________________________Rick...........
Note that it is the LM386N-4 that is spec'd for 1W; the -3 might make it there with a 4Ω load. The -1 part... nowhere close to 1W.
And sorry, AndrewT, but that is just wrong. The LM386 was designed mostly as a low-voltage audio amp for loudspeakers (roughly 40 years ago).
The Zobel network cap and any small power supply decoupling won't need to be electrolytic, but the larger values at pin 7 bypass and pin 5 output AC coupling will need to be.
BTW, the datasheets I'm seeing don't show the "curved plate" type of schematic symbol, but do have a "+" mark, denoting a polarized (i.e., electrolytic) capacitor. Don't let that get you confused.
And sorry, AndrewT, but that is just wrong. The LM386 was designed mostly as a low-voltage audio amp for loudspeakers (roughly 40 years ago).
The Zobel network cap and any small power supply decoupling won't need to be electrolytic, but the larger values at pin 7 bypass and pin 5 output AC coupling will need to be.
BTW, the datasheets I'm seeing don't show the "curved plate" type of schematic symbol, but do have a "+" mark, denoting a polarized (i.e., electrolytic) capacitor. Don't let that get you confused.
Sofa,
you are right.
My meory has let me down again.
But I did go back and read the datasheet again.
It clearly does not say "headphone" driver.
The data does support my contention that it is a headphone driver since the sensible outputs are in the range 10mW to 150mW.
I would not call that loudspeaker type driving, not even small loudspeakers, which are inherently of very low efficiency.
you are right.
My meory has let me down again.
But I did go back and read the datasheet again.
It clearly does not say "headphone" driver.
The data does support my contention that it is a headphone driver since the sensible outputs are in the range 10mW to 150mW.
I would not call that loudspeaker type driving, not even small loudspeakers, which are inherently of very low efficiency.
The old "386" really is an ancient unit....I'm surprised they still make them.
Right now I'm listening to a TDA 2822 chip........these things are everywhere but mostly reside in those dirt cheap plastic "Computer speakers" with about one Watt available & a super-wide V+ rating from 2V to 15V I believe makes it very flexible. Being that all tiny 2-3" , 20 cent drivers that reside in these plastic housed "computer speakers"....they are notoriously inefficient....the fix? Pull the guts out of those cheap plastic things & run some "real" speakers with em'. The SPL ratings for sure on those 'factory' drivers no doubt are in the low seventies worth of Db, about as low as you can get...........low power PLUS low efficiency PLUS poor accuracy makes for lousy sound.
_______________________________________________________Rick........
Right now I'm listening to a TDA 2822 chip........these things are everywhere but mostly reside in those dirt cheap plastic "Computer speakers" with about one Watt available & a super-wide V+ rating from 2V to 15V I believe makes it very flexible. Being that all tiny 2-3" , 20 cent drivers that reside in these plastic housed "computer speakers"....they are notoriously inefficient....the fix? Pull the guts out of those cheap plastic things & run some "real" speakers with em'. The SPL ratings for sure on those 'factory' drivers no doubt are in the low seventies worth of Db, about as low as you can get...........low power PLUS low efficiency PLUS poor accuracy makes for lousy sound.
_______________________________________________________Rick........
I wouldn't ever put the LM386 in a context of truly high-fidelity sound output, but it can come reasonably close in a headphone amp. And there are other threads here concerning power levels required for home listening. On the other hand, while NS suggests apps such as TVs and portable radios, I personally have only ever seen the LM386 used in telecomm equipment, like speakerphones and modem speaker drivers.
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