PS-X2 power supply for Aleph 5

[binspaul]

Hello,

I am working on Aleph 5 amplifier project based on the attached schematic from KK. I am stuck with the selection of Inductors for the power supply. The schematic diagram says that we should use 2.2mH inductors. What should be the min current rating required.

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Best regards,
BP

 

[Zen Mod]

sum of Iq , then multiplied with 2 , at least

take care that inductor is rated for DC

 

[Hikari1]

Hammond 159zl is what I am using.

10A, low losses.

 

[mpmarino]

Is it smart to fuse the rails independently on an Aleph? Could the thing go DC on output losing just + or - ?

 

[AndrewT]

Hello,

I am working on Aleph 5 amplifier project based on the attached schematic from KK. I am stuck with the selection of Inductors for the power supply. The schematic diagram says that we should use 2.2mH inductors. What should be the min current rating required.

---
Best regards,
BP

You could replace the inductor with a resistor or bank of paralleled resistors.
Alternatively you could wind your own air cored inductor using 0.6mm diameter enamelled copper wire.
Try using a bobbin ~20mm diameter with cheeks set ~10mm apart and wind on ~150Turns to give an overall diameter of ~35mm to 40mm.

The inductance will not be as high as 2.2mH, but it will give an L+R that has a higher impedance than the R on it's own.
The waveform seen on a scope changes from a slightly rounded sawtooth to a near sinewave with lots of 2nd & 4th harmonic. The HF harmonics are nearly all gone.
I have found this to work well on ClassA, on ClassAB and on very high bias ClassAB.

For a PSU that has to provide a lot of current I think the 22mF capacitor after the inductor is too small.
I would place both 22mF after the inductor and fill the empty space (before the inductor) with 5off paralleled 3m3F.
Use PSUD2 to investigate this and you may find an even better choice of values.

The 8A fuses after the main smoothing capacitors seem to me to ffer little in the way of added safety.
It would be far safer to fit a close rated mains fuse in the primary circuit. For 300VA on 220Vac supply try using T1.6A. It may operate well on a T1.25A
Both fuse options will require a properly sized soft start.

 

[binspaul]

Hello,

Can I use the following filter? The value seems to be matching as per the PCB design.

7448258022 Wurth Electronics | Mouser India

http://www.mouser.com/ds/2/445/7448258022-539312.pdf

---
Best regards,
BP

 

[Zen Mod]

nope

that's for small current .... think AC circuits

what you need is either heavy gauge air choke or heavy gauge big chunk of iron choke

think DC circuits

 

[binspaul]

Okay, got it. Will try with the Hammond 159ZL.