Pumpkin Shunty begins....

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Russellc

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Thanks, I just as well snag a couple. If they have it with shield, I will get it like that, otherwise, same as you got.
I assume you consider them adequate and no reason to up voltage or VA? Never mind, I dont see it in shielded version,
just ordered 2 of the same you used.

Thanks,

Russellc
 
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malgre

malgre

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Joined 2004
grimberg said:
The case is 17.25" x 14.25" x 3". The transformers are from Antek Inc. and have electrostatic shield. That shield combined with the aluminum wall separating the transformers from the circuit boards, made for an absolutely quiet pre-amplifier.
Regarding power tools, I only used the table saw with a Freud blade for non-ferrous metals and a drill press. Many members of this forum have ordered pre-cut aluminum plates from Online Metal Store and seemed happy with their products.
Click to expand...

Thanks for the info, and the link - I am remembering that I may have used that metal store, or another similar, for a case I did years ago. I have a few full chassis options that look good, so I may go that route if the sizes work.

Tod
 
malgre

malgre

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Joined 2004
shielding, and EI vs toroidal xformer

Russellc said:
Thanks, I just as well snag a couple. If they have it with shield, I will get it like that, otherwise, same as you got.
I assume you consider them adequate and no reason to up voltage or VA? Never mind, I dont see it in shielded version,
just ordered 2 of the same you used.

Thanks,

Russellc
Click to expand...

I've been looking at some of the products in this store for shielding:
[url]https://www.lessemf.com/mag-shld.html#276[/URL]
Don't know exactly what level is necessary, so maybe overkill, but I think I will at least partition the xformers off.

I am wondering why Zen Mod recommended:
Xformer – EI preferable, 82 to 100Vct / 300mA per channel (one Shunty) minimum .
Click to expand...
in the Shunty BOM and Schematic - I'm not sure I understand the tradeoffs here vs. toroidal???

Tod
 
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Russellc

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Well, these are like 11.00 bucks apiece, I am open to whatever, I can always use these with
something. ZenMod, do you have a comment? I want what Shunty-Pumpkin daddy knows is best! On the other hand, these appeared to work out for Grimberg.

What say master ZenMod?

Thanks all,

russellc
 
grimberg

grimberg

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Joined 2002
I initially started the pre-amp using two 2x45V 80VA transformers and, in my opinion, Shunty's Q1 and Q1a were running too hot to count on them working reliably for a long time. I was not able to keep my finger on the heat sink of either MOSFET for more than an instant. That's why I switched to the 40V units.
If you are interested in the 45V transformers, they are Plitron and I can give you a good deal on them.
 
Zen Mod

Zen Mod

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Russel - freely use what's already proven , if Grimberg tried exact type , that's it

regarding EI xformer vs. Donut - that's general consensus that EI are conducting less garbage from mains , but in this case that difference is purely academic , having all that filtering and regulation ( of Shunty) on hand .....

so - just use what's more convenient for you

trimpots - again - use normal multiturns , setting screw on top , and ( I just checked)-pins in line
 
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Russellc

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Zen Mod said:
Russel - freely use what's already proven , if Grimberg tried exact type , that's it

regarding EI xformer vs. Donut - that's general consensus that EI are conducting less garbage from mains , but in this case that difference is purely academic , having all that filtering and regulation ( of Shunty) on hand .....

so - just use what's more convenient for you

trimpots - again - use normal multiturns , setting screw on top , and ( I just checked)-pins in line
Click to expand...

Thanks for the info, orders going out, and I will use those transformers, and pots I have on hand.

Russellc
 
malgre

malgre

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Joined 2004
OK, I just ordered heatsinks, so I'm all in! Took a bit of doing to track them down (let me know if you're looking for them), hoping to get the transformers sorted tomorrow (I'm checking out some that I liked the look of in a build by jimbo51) and then go through my boxes of resistors and capacitors to see if I already have some of what's needed. Progress :)

Tod
 
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Russellc

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malgre said:
I've been looking at some of the products in this store for shielding:
[url]https://www.lessemf.com/mag-shld.html#276[/URL]
Don't know exactly what level is necessary, so maybe overkill, but I think I will at least partition the xformers off.

I am wondering why Zen Mod recommended:
in the Shunty BOM and Schematic - I'm not sure I understand the tradeoffs here vs. toroidal???

Tod
Click to expand...

I believe Mcmasters carries Mu metal...

Russellc
 
R

Russellc

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Joined 2003
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malgre said:
OK, I just ordered heatsinks, so I'm all in! Took a bit of doing to track them down (let me know if you're looking for them), hoping to get the transformers sorted tomorrow (I'm checking out some that I liked the look of in a build by jimbo51) and then go through my boxes of resistors and capacitors to see if I already have some of what's needed. Progress :)

Tod
Click to expand...

Well, dont be tight lipped, what did you get heatsink wise?:D ( and where , numbers i.e.) I may as well snag those as well...I havent even begun heatsink hunting, hopefully your finds will speed this along.

This kit has aged long enough!

Russellc
 
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Russellc

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Zenmod, it looks like I am going to have to stand those 1 watt metal oxides I asked about up "soldier style"......is there a suitable one that is small enough to fit the trace?Maybe that's why the list I l;ooked at showed those items from Newark...I will check their size.

Russellc
 
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malgre

malgre

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Joined 2004
Russellc said:
Well, dont be tight lipped,
Click to expand...
:yes: A fair point, well made. Maybe not so much tight lipped as lazy, I'll post links to parts from now on!

Russellc said:
what did you get heatsink wise?:D ( and where , numbers i.e.) I may as well snag those as well...I havent even begun heatsink hunting, hopefully your finds will speed this along.
Click to expand...

I got the Fischer SK81-50 SA and SK75-50, from the cookbook. I'm sure other options would work, or could be made to work, but with the spacing so perfect on the boards, I decided to hunt those down (I couldn't find the Austerlitz options at all). Unfortunately, I couldn't find a vendor that had both types, so I have two different sources:

SK75-50 Allied Electronics: Fischer - SK75-50-TO220 - Screw Mount 50 x 32 x 14mm 8.5K/W TO-220 Heatsink - Allied Electronics - $1.79 each, US, regular shipping for 4 was $6.41

SK81-50-SA Transfer Multisort Elektronik (TME): SK81/50/SA FISCHER ELEKTRONIK - Heatsink: extruded | TME - Electronic components - $3 each, Polish company, shipping was $9.90

Yeah, shipping 2 separate orders kinda hurt the cheapskate inside, but I will be happy with the result.

Tod
 
malgre

malgre

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Joined 2004
Russellc said:
Allied has the SL75-50, but 0 in stock, search continues.
Click to expand...

Ah, I missed that you had searched - yeah, 0 in stock, but Allied can get them, so I went ahead and ordered, figuring they'd arrive around the time I was ready for them, maybe use something temporary if I'm ready before they are here.

TME is cheaper than Newark/element 14 for the other heatsink (SK81-50-SA). I've never used them, though - they say the order should arrive in just a few days, will let you know how that goes.

Tod
 
Zen Mod

Zen Mod

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R

Russellc

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malgre said:
:yes: A fair point, well made. Maybe not so much tight lipped as lazy, I'll post links to parts from now on!



I got the Fischer SK81-50 SA and SK75-50, from the cookbook. I'm sure other options would work, or could be made to work, but with the spacing so perfect on the boards, I decided to hunt those down (I couldn't find the Austerlitz options at all). Unfortunately, I couldn't find a vendor that had both types, so I have two different sources:

SK75-50 Allied Electronics: Fischer - SK75-50-TO220 - Screw Mount 50 x 32 x 14mm 8.5K/W TO-220 Heatsink - Allied Electronics - $1.79 each, US, regular shipping for 4 was $6.41

SK81-50-SA Transfer Multisort Elektronik (TME): SK81/50/SA FISCHER ELEKTRONIK - Heatsink: extruded | TME - Electronic components - $3 each, Polish company, shipping was $9.90

Yeah, shipping 2 separate orders kinda hurt the cheapskate inside, but I will be happy with the result.

Tod
Click to expand...

Ok, Heatsinks ordered! Whew!

Russellc
 
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