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Pavel Dudek's super Gainclone group buy

Colour of the pcb

  • Black

    Votes: 31 37.8%

  • White

    Votes: 12 14.6%

  • Red

    Votes: 14 17.1%

  • Blue

    Votes: 13 15.9%

  • Yellow

    Votes: 3 3.7%

  • Green

    Votes: 13 15.9%
  • Total voters
    82
Jump to Latest
B

BNK

Member
Joined 2007
Upupa Epops said:
To jaybombalous : replace foil capacitors C11 and C15 by electrolyt type ( see text and BOM ) - with foil type is low frequency of amp too high - see again instruction manual...
Click to expand...


Pavel,

In the manual you refer to C14 (1u - treble, 47u - regular).
Was it meant C11/C15?
No remark on bridged mode (rather than parrallel, but I assume it's the same as on stereo/active).

Just now I noticed the original BOM in english-excel format... answered some of my questions (although I got to the same conclusion about the screws/washer).
 
J

jaybombalous

Member
Joined 2007
yeah ex007, no problem at all. Really u did a great service.

PA - excuse me for asking to make sure I am doing the right thing or lack there of... This is my second project that I have ever done and I was just asking some questions. I do not have the hundreds and thousands of hours into selecting electronic components like the rest of u geniuses.

To me the TO - 220 mica insulator, whatever, will not fit correctly on the back of the LM4780, I was looking for something else... Or a better answer. Maybe I am just so new, I just don't get it...
 
L

Landoctor

Member
Joined 2007
Thermal washers

jaybombalous,
What he is saying is that the LM4780 comes in an un-insulated package and thus needs further insulation if it will be exposed. You are fine to just mount it to the heatsink with a mica washer and a little thermal compound.

Donovan

Peranders,
In reading your first response it looks like you were saying that it was an insulated package ("all plastic"). I think that's where the confusion was coming from. In checking the datasheet I see that it is in fact not insulated, so will need a mica washer only if exposed.
 
peranders

peranders

Member
Joined 2002
sjostromaudio.com
Paid Member
Guys, don't you ever read the datasheet if you want some facts?

Note 14: The TA27A is a non-isolated package. The package’s metal back, and any heat sink to which it is mounted are connected to the V- potential when using
only thermal compound. If a mica washer is used in addition to thermal compound, ?CS (case to sink) is increased, but the heat sink will be electrically isolated from
V-.
Note 15: DC electrical test.


Meaning = NOT insulated!
 
B

BNK

Member
Joined 2007
Actually I hoped I can build this project without looking too much into the specs and without searching too much for components (that's why I try to help the others on the components BOM).

I don't tend to build too many amps (In the Jacomo article you posted on your site, as the daughters boyfriend, I would be with the daughter and NOT by the computer...).

I've chosen Pavel's gainclone to be my main amp(s) as it looked very promissing.

I think the best way for others to learn (the design and in general) is after receiving all the components,
And I think Pavel's amp does worth building, even for beginners.
 
J

jaybombalous

Member
Joined 2007
Send me a link to the page where I can buy a mica washer for a LM4780 chip. All the mica washers I seen will not fit, or at least don't look like they will.

This is my only problem, someone just post a god damn link to a mica washer so I can buy it all ready.


Irregardless of whether I need it or not, its in the BOM, so can someone please post a link to a mica washer I can buy for my LM4780 chip. Anyone...


BTW, I don't plan on putting the amp in a case right away, so thats why I wanna isolate the chip, so I can isolate the heat sink from me doing dumb **** when its running and blowing it up.
 
J

jaybombalous

Member
Joined 2007
Ok, so now I understand it a little more... I have yet to see these impregnated silicone washers...

Now all makes sense, just confusing when someone expects me to know how to accomplish something when I have never done it before or even seen it done before.

Thanks ppcblaster for a link so I could at least research the type of material I need.
 
B

bobgroger

Member
Joined 2005
jaybombalous said:
Ok, so now I understand it a little more... I have yet to see these impregnated silicone washers...

Now all makes sense, just confusing when someone expects me to know how to accomplish something when I have never done it before or even seen it done before.

Thanks ppcblaster for a link so I could at least research the type of material I need.
Click to expand...

jaybombalous,

Here is the exact item you are looking for
http://rocky.digikey.com/WebLib/Bergquist/Web photos/Q3-67, 101.jpg

Available from Digi-Key as part number BER136-ND
http://dkc3.digikey.com/PDF/T072/P1013.pdf for $0.49\ea

As others have said there are many ways to deal with this but you can never go wrong buying the correct item!

Bob G.
 
B

BNK

Member
Joined 2007
peranders said:
If you plan to use it in heavy duty, it may be better to use 18 VAC but since the IC has over temperature protection you can use a higher voltage and possibly experience distortion at real high output power but the amp will not die.
Click to expand...

Looking at the LM4780 specs I understand that higher the better.
If the IC has over temp protection I don't understand why not use 25vac even on high load applications?

I'm just about to order the toroids and I thought of a toroid that can be used in mono & stereo modes (25vac, 24vac, 22vac?).
 
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