I'm thinking about a project based on bridged LM386 chips, with multiple paralleled per "side" and 4+ watts of output, for a portable bookshelf speaker with a built in battery/amp.
I'm thinking about the LM386 for a few reasons... they're easy to work with and can be used with extremely simple circuits, require only 1 power supply rail, and a setup like this would be scaleable-- decrease speaker impedance and increase the number of parallel chips for more power. They also don't require a heat sink (as opposed to some chips that would provide several watts of power on their own) and they've been proven to operate in cigarette boxes, mint tins, and other small enclosures without melting. They're also dirt cheap so building an amp with ~8 of these could cost $15 in parts (excluding batteries which I plan to be rechargeable, possibly lithium-polymer)
The problem is that LM386's come in a confusingly large number of variants... M versions are almost useless for poweramps with a dissipation under 1/2 of the N series. Within the LM386N series the LM386N-1 and -3 versions have a supply voltage rating of 15v, but the -4 is rated at 22v.
Because I'm expecting to parallel chips, voltage (as well as how low an impedance speaker I use) will be the limiting factor in how much power I could get out of this setup.
It's been a couple years since I ordered a batch of these chips, but I remember getting a really inconsistent selection. I was buying them to build 1/2W guitar amps (similar to the Little Gem circuit) and once got a lot of N-4s, once an assortment, and once I even got an -M (which won't even work for that application). Does anyone know of a reliable site where I could order LM386N-4 chips and not have to worry about getting another LM386? This could be a very economical project but not if I need to buy 4 ICs for each one I can actually use
Of course, any thoughts on this project including other circuit ideas or any experience with a similar one would be much appreciated!
I'm thinking about the LM386 for a few reasons... they're easy to work with and can be used with extremely simple circuits, require only 1 power supply rail, and a setup like this would be scaleable-- decrease speaker impedance and increase the number of parallel chips for more power. They also don't require a heat sink (as opposed to some chips that would provide several watts of power on their own) and they've been proven to operate in cigarette boxes, mint tins, and other small enclosures without melting. They're also dirt cheap so building an amp with ~8 of these could cost $15 in parts (excluding batteries which I plan to be rechargeable, possibly lithium-polymer)
The problem is that LM386's come in a confusingly large number of variants... M versions are almost useless for poweramps with a dissipation under 1/2 of the N series. Within the LM386N series the LM386N-1 and -3 versions have a supply voltage rating of 15v, but the -4 is rated at 22v.
Because I'm expecting to parallel chips, voltage (as well as how low an impedance speaker I use) will be the limiting factor in how much power I could get out of this setup.
It's been a couple years since I ordered a batch of these chips, but I remember getting a really inconsistent selection. I was buying them to build 1/2W guitar amps (similar to the Little Gem circuit) and once got a lot of N-4s, once an assortment, and once I even got an -M (which won't even work for that application). Does anyone know of a reliable site where I could order LM386N-4 chips and not have to worry about getting another LM386? This could be a very economical project but not if I need to buy 4 ICs for each one I can actually use
Of course, any thoughts on this project including other circuit ideas or any experience with a similar one would be much appreciated!
