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Author Topic: Heatsinks for your poweramp  (Read 66003 times)

tonyharker

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Re: Heatsinks for your poweramp
« Reply #75 on: December 10, 2017, 12:57:54 PM »

The LM386 is not an op amp but a power amp, albeit low power.  It could be getting hot because it it is oscillating. It should be cool if it is idling ie not passing a signal.
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Jazz P Bass

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Re: Heatsinks for your poweramp
« Reply #76 on: December 10, 2017, 01:55:41 PM »

The LM386 is Not simply an opamp.
It is a power amplifier in it's own right.

The quiescent current with a 12Vdc supply is in the milliwatts.
So that wont make you say ouch.
The power dissipation of the package is 500 milliwatts (1/2 watt).
Again, no need for a heatsink.

If the device got that hot, it is hooked up wrong.
Most probably it is now bad.
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flester

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Re: Heatsinks for your poweramp
« Reply #77 on: December 11, 2017, 09:22:07 AM »

The LM386 is Not simply an opamp.
It is a power amplifier in it's own right.

The quiescent current with a 12Vdc supply is in the milliwatts.
So that wont make you say ouch.
The power dissipation of the package is 500 milliwatts (1/2 watt).
Again, no need for a heatsink.

If the device got that hot, it is hooked up wrong.
Most probably it is now bad.
Thanks. Almost certainly was mis-wired but have sorted it out and runs fine on the breadboard and no longer gets hot. Seems to still work but I have spares anyway

Sent from my SM-G935F using Tapatalk

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Jazz P Bass

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Re: Heatsinks for your poweramp
« Reply #78 on: December 11, 2017, 10:45:07 AM »

Those are nice Ic's.

Good to know that they are robust enough to survive being 'hooked up wrong'.

Any idea what mistake you made?

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GB

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Re: Heatsinks for your poweramp
« Reply #79 on: August 09, 2018, 06:38:37 AM »

Hi Guys... notwithstanding the (very valid) point about them failing... Cooling Fans can be very effective... potentially reducing the size of a given heatsink by 50% - or more.
Attached is a pic of a 100 watt with a relatively small heatsink - but with two 40mm fans directed down the cooling fins. The amp runs of a nominal 50 volt supply so these are two 24 volt DC units - with a little bit of additional circuitry to ensure that the voltage is equally distributed between them.
Bottom line it works very well.
PS. I have contemplated adding some sort of thermal protection (fuse or breaker) as a last line of protection - but haven't got that far yet.

GB
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