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?
Those rectifiers aren't available in Sweden (haven't found them, anyway) so what kind can I use instead?
AndrewT refered to the PSU in post 5, because dual rectifiers are used with a center-tapped transformer. They only make sense with a dual secondaries transformer.
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.
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:
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)
the schematic is attached here......
You could leave CIA away. CIB could become 47 µF then.
You will have to recalculate Rm, if you use ~24 V DC rails. Should be 10..12 k then.
You will have to recalculate Rm, if you use ~24 V DC rails. Should be 10..12 k then.
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.
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!
Sorry,didn't get it........once again please.😕
what value electrolytic should I use??
please refer to the PSU schematic too (attached here)
AndrewT said:
Sorry,didn't get it........once again please.😕
AndrewT said:
what value electrolytic should I use??
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.zinblade19 said:
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 AndrewT,
thanks for your reply.
I would be using a centre-tapped transformer,
& a single bridge rectifier..........
I just wanted to show u the filter ckt of the rectifier..
I would be using EI transformers, any major disadvantages??
(didn't see anyone using it here)
😉
thanks for your reply.
I would be using a centre-tapped transformer,
& a single bridge rectifier..........
I just wanted to show u the filter ckt of the rectifier..
I would be using EI transformers, any major disadvantages??
(didn't see anyone using it here)
😉
If you compare a 200VA toroid with a 200VA EI you will notice the toroid is smaller!
I have read that toroid's are more efficient to. Lower losses.
I have read that toroid's are more efficient to. Lower losses.
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.
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.
AndrewT said:
Hi Andrew!
in the PCB layout Mute & gnd does not share a trace with signal gnd or NFB lower leg.
Anyway, can you tell me -- what would be the result with it???
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