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Old 13th April 2015, 05:23 PM   #1
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Default Look ma, no center tap

Retrofitting an LM4780 chip amp into an old Fisher Console -- no CT on the power transformer. This works as a rail-splitter for a more demanding load:
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Old 14th April 2015, 02:33 PM   #2
DF96 is offline DF96  England
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Are you sure? What do the upper three diodes do? As wired, not what the lower three diodes do!
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Old 14th April 2015, 02:50 PM   #3
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Jack, the real test here is with asymmetrical loads. Load it so that the pos side needs, say, 3A and the neg side 0.3A Then see what happens.

Jan
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Old 14th April 2015, 03:02 PM   #4
wwenze is offline wwenze  Singapore
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A rail splitter is essentially an amplifier that outputs a "nothing"

Or, you can run your LM4780 in bridged mode so that negative terminal can output something more useful. That's how the cheap stuff are powering their speakers, because bipolar supplies are expensive.
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Old 14th April 2015, 07:29 PM   #5
Ketje is offline Ketje  Belgium
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Quote:
Originally Posted by jackinnj View Post
Retrofitting an LM4780 chip amp into an old Fisher Console -- no CT on the power transformer. This works as a rail-splitter for a more demanding load:
The datasheet of the LM4780 shows how to use it with a single supply.
Mona
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Old 16th April 2015, 06:31 AM   #6
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Virtual ground.
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Old 21st April 2015, 07:04 PM   #7
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Quote:
Originally Posted by jan.didden View Post
Jack, the real test here is with asymmetrical loads. Load it so that the pos side needs, say, 3A and the neg side 0.3A Then see what happens.

Jan
How about a nice muscular servo? Are you hinting at Figure 2 of LA#9's article "Low Parts Count Amplifier"?
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Old 21st April 2015, 07:27 PM   #8
RNMarsh is offline RNMarsh  United States
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Quote:
Originally Posted by jackinnj View Post
Retrofitting an LM4780 chip amp into an old Fisher Console -- no CT on the power transformer. This works as a rail-splitter for a more demanding load:




-RNM
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Old 27th April 2015, 06:09 PM   #9
Binely is offline Binely  United States
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I have an old fisher tuner I would be interested in retrofitting too. Uses a couple of old sanyo IC's. Interested in collaborating?
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