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Old 27th November 2009, 03:29 PM   #6111
udailey is offline udailey  United States
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A blob of that arts/crafts glue stick stuff that you put in a gun and heat it up so that you can spread it ... if you seal them together with this they will stay the same temp as the glue will act as a heatsink and will heat up evenly. No.. it wont get warm enough to turn back into glue.
Ri
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Old 27th November 2009, 05:01 PM   #6112
tinitus is offline tinitus  Europe
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If the Jfets are glued into a massive chunk of aluminium, the temperature will just be below that of the inside box, 100% stable, always

I have considered this before, but thought it was much too impractical, in many ways

But the solution is quite simple
Place the Jfets horisontal
Then the massive heatsink can be screw mounted

Oh, yeah, drill a few exstra holes fore future mods, like a cascode
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Last edited by tinitus; 27th November 2009 at 05:05 PM.
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Old 28th November 2009, 05:11 AM   #6113
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i made some progress tonight - doin' it the "big dumb way".. 33,000uF Panny UP x4. Panny power resistors. red G-10 board is 3-1/8 by 6-3/4. block rectifiers will flank the board, mounted directly on the chassis bottom.
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File Type: jpg 013.jpg (424.5 KB, 861 views)

Last edited by fishski13; 28th November 2009 at 05:36 AM.
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Old 28th November 2009, 01:44 PM   #6114
udailey is offline udailey  United States
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Looks 'smart and compact' to me. Nice job man.
Uriah
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Old 28th November 2009, 02:58 PM   #6115
osscar is offline osscar  Latvia
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Nice PSU , im still working with enclosure (sanding, dtilling ...boring) i hope amp will be ready till end of next week.
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Old 28th November 2009, 08:24 PM   #6116
Ryssen is offline Ryssen  Sweden
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Quote:
Originally Posted by Nelson Pass View Post
I find that the most important details relate to the bandwidth.
The typical - 3dB point is out around 1 MHz, so without
compensation you can see all manner of effects.

Any time there is a question about this possibility, it's helpful
to throw a small capacitor across the feedback resistors and
see if it changes anything.

I had to limmit the bandwith because I got oschillation(uncuntrolled heating)when connected to a DAC via transformers.Anyway I used a 2,2nf across R10 and that stopped the oschillating(heating)but I think I got some less detals after,can the 2,2nf cause that?Should I use a smaller cap to keep out of the hearing area?
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Old 28th November 2009, 09:32 PM   #6117
alazira is offline alazira  United States
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Quote:
Originally Posted by Ryssen View Post
I had to limmit the bandwith because I got oschillation(uncuntrolled heating)when connected to a DAC via transformers.Anyway I used a 2,2nf across R10 and that stopped the oschillating(heating)but I think I got some less detals after,can the 2,2nf cause that?Should I use a smaller cap to keep out of the hearing area?
Hi Ryssen,

I think R10 is a ground reference, not part of the feedback. To limit the bandwidth the cap needs to be on R5 and R6 (plus R7&R8 if used). Perhaps you can also consider increasing the gate resistors (R9, R13, R14) to see if it fixes the problem? Trimpot might be a friend here. If I'm mistaken (quite possible as my grasp is tenuous) someone please correct me.

Garrett
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Old 28th November 2009, 10:11 PM   #6118
tinitus is offline tinitus  Europe
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Correct, it is R6-8
I was recommended a cap in the pf range, but to be checked with instrument
I suppose that if you mount the wrong size cap you will just get a "ringing", and still have not dealt with the problem
Isnt 22-100pf often used
100pf is like 0.1nf, right

If you use multiple outputs, its also been adviced to increase R11/12 source resistors to maybe about 1ohm

Last edited by tinitus; 28th November 2009 at 10:25 PM.
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Old 28th November 2009, 10:34 PM   #6119
Ryssen is offline Ryssen  Sweden
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In the manual it says"You can limit frekvency responce by an input capacistor across R10,and allso in the feedbackloop with capasistance across R5 and/or R8,i have choosen not to"

I tried caps across R5 and R8 with no effekt on the problem,cap across R10 had effekt,maybee to much...
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Old 28th November 2009, 11:06 PM   #6120
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by Ryssen View Post
I tried caps across R5 and R8 with no effekt on the problem,cap across R10 had effekt,maybee to much...
Ofcourse, it makes perfect sense
R9 and R10 are there exactly to deal with problems like yours, oscillation caused by a connected source
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