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July 04, 2022, 05:15:34 AM

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Heatsinks for your poweramp

Started by joecool85, April 05, 2006, 07:37:26 PM

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tonyharker

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.

Jazz P Bass

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.

flester

Quote from: Jazz P Bass 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.
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


Jazz P Bass

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?


GB

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

mandu

Year 2001 application note from ON semi regarding mounting considerations for power semiconductors. Regards.