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Chip Amps Amplifiers based on integrated circuits

Lm3886 question
Lm3886 question
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Old 4th July 2019, 11:14 AM   #1
diy didi is offline diy didi  South Africa
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Default Lm3886 question

Hi.
Can Someone tell me what the function of the 270 ohm 2W resistor is on the output of the LM3886?
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Old 4th July 2019, 03:47 PM   #2
tomchr is offline tomchr  Canada
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At first glance, it looks like the on-board heater...

Could it be compensating for a load that goes very high impedance at some frequency?

Tom
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Old 4th July 2019, 03:58 PM   #3
leadbelly is offline leadbelly  Canada
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Originally Posted by diy didi View Post
Hi.
Can Someone tell me what the function of the 270 ohm 2W resistor is on the output of the LM3886?
Why why why be so cryptic? What is it? Do you own it? Do you have another diagram with connector printout? Do you know what outputs the device actually has?
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Old 9th July 2019, 04:36 AM   #4
Stuey is offline Stuey  Australia
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Headphone out?
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Old 9th July 2019, 12:31 PM   #5
Max Headroom is online now Max Headroom  Australia
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Originally Posted by leadbelly View Post
Why why why be so cryptic? What is it? Do you own it? Do you have another diagram with connector printout? Do you know what outputs the device actually has?
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Indeed.
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Old 9th July 2019, 12:33 PM   #6
Max Headroom is online now Max Headroom  Australia
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Originally Posted by diy didi View Post
Hi.
Can Someone tell me what the function of the 270 ohm 2W resistor is on the output of the LM3886?
It is a DC load, not strictly necessary but would reduce startup thump.
Dan.
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Old 9th July 2019, 05:25 PM   #7
tomchr is offline tomchr  Canada
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Adding load to the LM3886 won't do anything to reduce any start-up thump. The LM3886 doesn't have much of a start-up thump anyway if you're using the mute circuit given in the data sheet and size the mute resistor properly. My LM3886 amps all start up quietly.

Tom
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Old 9th July 2019, 06:47 PM   #8
adason is offline adason  United States
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Headphone out?
Not the way its connected. It would have to be disconnected from ground.
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Old 9th July 2019, 11:34 PM   #9
BrianL is online now BrianL  United States
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Lm3886 question
This appears to be a schematic for one channel of power amplifier in an Allen electronic organ. Speakers are almost always some distance from the console which usually contains the amps. Apparently they wanted to always have some minimal load on the output even if the speakers were disconnected. I don't know why but it likely doesn't hurt anything
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