Single sided non inverting LM3886 PCB

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Sorry for bringing upp a rather old thread, but I have some questions! AndrewT said that one rectifier is not correctly shown, but whats wrong with it?
Those rectifiers aren't available in Sweden (haven't found them, anyway) so what kind can I use instead?
 
use the 4diode integrated rectifier bridge, available in the high current metal cased version or in lower current plastic cased and 4-in-line pins.
Alternatively, use To220 single diodes to construct a bridge
or use 1n5402/3/4 to create your own very cheap bridge.
Sugden use 8 off 1n5404 to charge +-20mF to +-75Vdc and I have never had a failure.
 
ArtiomR said:
But I think, there is one mistake in your schematic and PCB - R2 resistor should be connected between Cin and R1, so that they form a high pass filter ;)
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Hi AndrewT,
is the schemetic originally posted by tla-Audio wrong, as mentioned??

Is this a good design for the lm3886??

I'm thinking of using it, any modification??
(would be using 18-0-18, 3A trans for each ch):hot:

the schematic is attached here......
 

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Hi,
compare that schematic to National's recommendations.

It has duplicated the RF input cap. 1n5F will probably take off too much treble. I reckon 1.5us is top limit.

Both Cs are wrong. They should include an electrolytic on each polarity and should connect together before going to Power Ground.

L1 should have a resistor in parallel to create the HF load. Somewhere between 2r7 and 10r.

Mute and GND should not share a trace with Signal Ground and NFB lower leg.
 
Hi!

AndrewT said:


It has duplicated the RF input cap. 1n5F will probably take off too much treble. I reckon 1.5us is top limit.


Sorry,didn't get it........once again please.:confused:



AndrewT said:
Both Cs are wrong. They should include an electrolytic on each
polarity and ......

[/B]

what value electrolytic should I use??


please refer to the PSU schematic too (attached here)
:bigeyes:
 

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zinblade19 said:
please refer to the PSU schematic too (attached here)
a centre tapped transformer must use a single bridge rectifier to create the dual polarity supply.

The dual rectifier version you have shown can only be attached to dual secondaries.

Look up National's datasheet for the Cs description.

your schematic shows 1n5F and 220pF as the RF attenuation filter after the 1k0 plus Rs from your source.
Let's assume Rs=100r.
the RF filter ~ 1k0+100r and 1n5F+220pF ~1.9us.

The normally recommended range for the RF filter at the front end of a power amp is 0.5us to 1.5us.

You need to reduce your capacitor values and check the Rs of your source.
 
Hi,
toroids are generally more efficient. The result is that they run cooler.
Toroids are generally lower regulation. The result is that the voltage sags less under load.
Toroids offer size and weight advantages to manufacturers of amplifiers that do not apply to us DIYers.
Toroids pass more high frequency artifacts. This results in more noise getting through the PSU to the circuit beyond.

A high quality EI designed for good regulation and low magnetic fields will perform very well, but it will weigh far more and cost far more than an equivalent high quality toroid.
 
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