[neilwight]

been beginning to build up my GSSL and my fears ref my 0.1 capacitors being too large physically have been founded.

theres no way that these are going to fit into the spaces no matter how i jiggle them.

since i now need to order replacements i'd like some advice.

firstly, will any 0.1 capacitors work in this circuit or do they need to be poly versions or will any kind work?

can anyone give me info of ones they have managed to use in this circuit with some level of easiness of fitting.

i'm in the UK but can easily cross reference to get an idea what i should be looking at.

[Mark Burnley]

Hi Neil,

The 0.1u (100n) caps are all PSU decoupling caps (as far as I can remember) Ceramic disk or plate caps are the best to use here- these are the small circular type- usually brownish colour, but sometimes dipped in blue or red epoxy.

If you can handle the torment that is Maplin, these will do:

Maplin RA49D

In PSU decoupling apps, ceramic actually outperform other types of cap at higher frequencies,.

Mark

[bcarso]

Some stacked film mylars are also pretty good, and also compact.  I tend to shy away from the high-K ceramics because of the large tempco, microphony, and other losses, but admittedly these are mostly an issue when they sneak into other parts of a circuit.  As PS bypasses, the ceramics are usually fine and also low inductance.

Sometimes the losses in caps work to damp ringing so are not necessarily bad.  In ham radio books you can see recommended the use of various caps with the lead length tuned to series-resonate at the fundamental of the circuit, so as to provide a very low Z at that one frequency.  I don't know if that technique has been revived for switchmode amps yet, where you would require at least a few caps tuned to different harmonics of the switching frequency.

[Mark Burnley]

Yea,

I tend to use ceramic for PSU decoupling, and polystyrene for signal-path areas such as op-amp feedback loop compensation and external comp caps. These epoxy-coated ceramics I linked to have been surprisingly stable in a range of apps- some of those cheap ceramic discs actually become physically damaged a bit too easily.

Mark

[Ptownkid]

WHat about polyesters?

[neilwight]

mark,

thanks a million for that...good advice and a good link.
i got a few items from maplin already for this so its an acceptable solution for me.

thanks everyone for the discussion too. some good reading there for my education

[bcarso]

WHat about polyesters?

Same as mylars.

[Ptownkid]

I've got a bunch of phillips polyesters kicking around if you need some...

[drpat]

...

[pstamler]

Kev Ross' list has them listed as "100nF Poly (MKT)".

I don't know if that means Polyester or Polypropylene. The WIMA site had no "MKT" type capacitors listed. I'm building two units, so I just ordered polyester for one unit and polypropylene for the other. I found WIMA's in 5mm lead pitches to use there; hope they're not too big! I read, from Jakob of Gyraf, that the caps on this board aren't that critical.

MKT is polyester -- I think the T stands for "terephthalate" but I could be wrong, and I also could be misspelling it. MKP is polypropylene.

Peace,
Paul

[bcarso]

Stamler wins:

"Mylar is a trade name of DuPont Teijin Films of Hopewell, VA for biaxially-oriented polyethylene terephthalate (BOPET) polyester film "

BOPET.  Hmmm ---that has somewhat sinister connotations.  But it has been a long day.

Panasonic has some extraordinarily compact mylar stacked film caps, which a client did not find and shipped me some enormous ones instead.  Fortunately I had some of the small ones which showed up during a thorough search.

[Svart]

i use Panasonic polyester and polypro for most everything i do these days.  Polyester for the jellybean parts and polypro for the audio path parts.  work nice and usually come with LONG leads which get you over and around most other parts when putting them in tight spaces.  this is how I got the .1s into my ssl compressors.. I used polypro here and they are much larger than the same value/voltage polyester.  with some slight adjustment of parts surrounding them and their longer legs, they fit quite nice.

 :thumb:

[Greg]

I used WIMA 5mm polys and they all will not fit in the board because of surrounding parts. I just used some jumpers and some glue to mount the caps elsewhere on the board.

Something kind of like this:
http://members.cox.net/capstanrecording/GSSL/G4000_202_Top.JPG

[gyraf]

..you can always mount from the bottom side if you run out of board space..

[SSLtech]

..you can always mount from the bottom side..

 :shock:

Keef

[gyraf]

Damn, you have a dirty mind, keef..  :oops:

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