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Swordfishy/ASPEN FETZILLA power amp

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FETZILLA group buy

Fetzilla pcb Group Buy Update - Now at 78 boards!!

2+P JoMo Adelaide SA Australia
2+P Ian Finch Coffs Harbour NSW Australia
2+P Gennaji Hyderabad India
2 Ken Lewis LA USA
2 Ron Russell Kent UK
2+P John Kenny Dublin Ireland
2+P Francis Morrin Dublin Ireland
2+P Vitalica Bucharest Romania
2+P Erik Deinum Groningen Netherlands
2+P Keith Correa ? India
2 Igor Polyakov California (city?) USA
2 Steve (aka SRH) Whangarei New Zealand
2+P George (aka JKC) Calgary Canada
2+P Anthony Mills Gold Coast Australia
2+P Dinesh (aka Chlorofille) Christchurch New Zealand
2+P Colin S. (?) (city?) NSW Australia
2 Chris Powell Sydney Australia
2+P Danny (?) Lierde Belgium
2 Sonnya (?) City (?) Denmark
4+P Jozua Cape Town South Africa
2 JT (? aka Sandyhooker) City (?) Arizona USA
2+P Nicola City (?) Vincenza Italy
2+P Sparkey (Brian ?) Melbourne Australia
2+P Chalkandtalk (?) City (?) NW England UK
4+P Woody1911a1 (?) Marblehead , MA USA
4+P George Cherhit Sacramento CA USA
2+P Tore Martensson Malmoe Sweden
2+P Steve Harrison Rock Springs WY USA
2 Kannan_S Austin TX USA
2+P NCC (?) Hanoi Vietnam
2+P VZS (Zsolt ?) Cluj-Napoca Romania
4+P Vitalica Bucharest Romania
2+P John Hambek Fort Worth TX USA
2+P Halcon83 City? USA
2+P Jonathon Rosser City? UK

I have attached:

#1 Parts list for ONE module, double for both
#2 Composite pcb layout gif showing latest changes.
#3 Pcb overlay LEFT side
#4 Pcb overlay RIGHT side
#5 Fetzilla circuit schematic
#6 Fetzilla power supply schematic
#7 Bottom foil layer of pcb
#8 Top foil layer of pcb

This is the latest edition, updated 22nd July 2011, and it incorporates all changes to this point.

This is, I believe, one of the most documented projects on this forum and I hope it gives a lot of people great pleasure. Many heads went into it and it was reasonably fast. Here's hoping..... nearly there.

As requested before, please, no money at this stage; I want to have all parts and boards and all address details BEFORE I despatch. I will contact people as a group in the Aspen forum when I'm ready to roll....

Cheers,

Hugh
 

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Where are the Exicon Mosfets going to come from?
Profusion only has the p channel in stock.

There are some places that show some inventory, but they require large lot purchases, or have high minimum dollar order.

Are the 2SK1058/2SJ162 mosfets good for this amp? These are much easier to find.
 
All the Lateral mosFETs are virtually the same.

Some say the original Hitachi versions (both the To3 j50/k135 and the To247 j162/k1058) were better than the later versions. These are not easy to find and generally are not cheap.

Aksa has said that the ClassD versions may not be as good.
http://www.diyaudio.com/forums/aksa/191053-swordfishy-aspen-fetzilla-power-amp-4.html#post2642168
http://www.diyaudio.com/forums/aksa/191053-swordfishy-aspen-fetzilla-power-amp-4.html#post2642179
http://www.diyaudio.com/forums/aksa/191053-swordfishy-aspen-fetzilla-power-amp-4.html#post2642182


Best to read both threads for details that have been discussed in detail (to death).
 
Hugh,

Could you please make provision for bigger C13 and C14 caps on the PCB. There is only 5mm lead spacing on the board but most of the caps above 1uF have lead spacing between 15mm and 25mm. There is plenty of room on the board to accommodate bigger caps at this location. Thank you.

Regards,
George
 
Hi Jonathan,

Thank you for you post - the components you mention are indeed on opposite sides, and the pcb has two 3/8" x 1/8" washers each of 0.8mm thickness raising it above the top of the output device. This places the solder joints under the pcb a good distance above the output devices. I have used this technique on commercial amps for some years and it NEVER causes difficulties.

You are on the list, along with Halcon83 and John Hambek!

George, corrections made.

Steve, the 2SK1058/2SJ162 can be used without any problem; just about any lateral fet with 8A, 160V and 100W will do the job fine. These devices are not particularly critical, the most critical are the smaller fets in the circuit.

I have attached all relevant files which match those presented on the other thread. They are dated 22nd July 2011.

Cheers,

Hugh
 

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Hugh,

Looking at the earlier posts, the SOT223 package has been chosen to allow higher dissipation in the VAS. I have not done the sums on the dissipation but the current layout might not allow much leeway to utilise the dissipation allowed by the device.

Designs I have done using these types of SM packages have relied on significant copper lands being placed to achieve the degree of heatsinking required, the package alone is often insufficient. The ZVP2110 datasheet is not very helpful here.

See http://www.fairchildsemi.com/an/AN/AN-1028.pdf

For example, swapping T2 and R7,8,9 and filling a copper area towards R16/D4 would improve things. You may of course be fine as it is - best to check :)

Regards,
Jonathan.
 
Of course I have done the homework here, c'mon, have some faith!

The dissipation of the device is 430mW. Rating (max) of the device is 2W.

This is less than one fifth of the max. The lands specified are 20% oversize on the recommendations for the SOT223 package, and they are duplicated for the larger drain pad on the reverse side and connected thermally by two vias besides.

You will also notice hugely oversized pads for the TO92 devices as well. Again, overkill.

This thing will be better cooled than a nuclear reactor.....

Cheers,

Hugh
 
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