Need some pointers for my first amp build

[Rainmaker91]

  I don't know what the price is of V-D resistors in your country.  We pay 10 cents.  If it's more than that, then there's something special about that particular resistor and you should look elsewhere, which is what you did, I suppose.  Still, that resistor is only 50 cents on US-Mouser.
 
I'm not sure if 20 hours is the time limit on alkalines feeding a CMoy, but I suspect it's really 4 or 5 times that, if not more.  A lot will depend on how much current you let that LED burn.  Otherwise, there's very little being used.  It's been awhile since I had a CMoy, but I don't recall only 20 hours.
 
I built a couple of PIMETAs that I still have.  Those are all solid-state and more or less a buffered-output version of a CMoy.  I have both heavily biased into Class A at the buffers and they will only last about 5-6 hours.  That I understand and remember, but a CMoy at 20 hours sounds wrong.

I was just guessing really, since that was more of the time frame I was expecting. If I'm looking at 60+ hours of playtime with the CMoy then I won't even bother getting rechargeable batteries at all. Would you recommend running it with a serial battery set-up or simply a parallel one? I am unsure how the one on tangentsoft is set up so I'm only asking to be sure I get the correct resistor for the LED and so that I won't fry the components with to high a voltage (not sure if any of the components have that low max rating though)
 
As for the V-D resitors... things tend to be overpriced here anyway, but for some reason they are about 3USD each which is insane.

 

[Rainmaker91]

Also did some recalculations for the LED using 18v and 10ma (half of the listed one at 20ma) I got 1500Ohm and 1/2w. Meaning this resistor should suffice then: http://no.mouser.com/ProductDetail/Vishay-Dale/RN65D1501FRE6/?qs=sGAEpiMZZMu61qfTUdNhG211dyJEeO6wk8rTTTf%2f6ck%3d
 
The same calculations on 9v and 10ma leads to 680Ohm and 1/8w. Meaning this should be fine then: http://no.mouser.com/ProductDetail/Vishay/RN55D6800FB14/?qs=BjwTfpAx95YZBJIGc8zi5w%3d%3d
 
I will just add both and order now I think. Then I will order up some more resistors at a later point if what I have doest work out.
 
came up at a total price of 348.17NOK which just below the tax limit. That is without the protoboard though so I'll have to see if I can source that locally, or maybe just make one myself ( I have sheets of acrylic, and PVC so maybe...).

 

[Rainmaker91]

Actually, considering the board... I think I have some thick aluminium tape that should work brilliantly for making circuits. So maybe I'll just cut to size and fix it on to an acrylic sheet (1-2mm thick), drill some holes for the components and I have a fully working circuit board. I just need some working pcb layouts for a single layer PCB...
 
Concerning that specific line of thought, there are some parts of the schematic that I don't fully understand. Specifically there are some lines going out in to nowhere, they all have a AGND symbol so I assume they are all conected to the AGND in the power section? There is also the OpAmp, but I suspect I will understand that better when I have it in front of me.

 

[30Cal]

You have it correct.  AGND is the virtual ground created by the voltage divider resistors in the power supply section.

 

[Rainmaker91]

  You have it correct.  AGND is the virtual ground created by the voltage divider resistors in the power supply section.

that makes sense. I'm trying to drawp up a clean circuit board layout in TinyCAD at the moment, but I can't seem to get my head around the mess that is the opamp. I would prefer to do the board as a single sided board (form my understanding only one side of the PCB has the leads), but I might have to do a double sided one (leads both on top and bottom of board).
 
You wouldnt happen to know of a more easy to follow layout of the DIP-8 opa than what is shown on tangentosft? I mean not that the layout shown there isnt good, it's just so specific to that board.

 

[tomb]

 

  You have it correct.  AGND is the virtual ground created by the voltage divider resistors in the power supply section.

that makes sense. I'm trying to drawp up a clean circuit board layout in TinyCAD at the moment, but I can't seem to get my head around the mess that is the opamp. I would prefer to do the board as a single sided board (form my understanding only one side of the PCB has the leads), but I might have to do a double sided one (leads both on top and bottom of board).
 
You wouldnt happen to know of a more easy to follow layout of the DIP-8 opa than what is shown on tangentosft? I mean not that the layout shown there isnt good, it's just so specific to that board.

 
 
Go to Google.  Select "Images" from the menu at top right and enter "CMoy layout" into the search field.

 

[Rainmaker91]

   
 
Go to Google.  Select "Images" from the menu at top right and enter "CMoy layout" into the search field.

Such a nice way to say "just google it"  
 
Anyway, would this do fine for a layout?

 
Actually, ignore that first layout. I think this one was way easier to follow: http://www.head-fi.org/t/183397/need-help-with-cmoy-parts/30#post_2194006

 

[tomb]

Ha!  An mb3k post!  He was one of the better DIY-er's on Head-Fi, but for some strange reason, he decided to do other things:
 
http://www.modelmayhem.com/484419
 
I just can't understand why that guy isn't interested in headphones anymore.

 

[Rainmaker91]

  Ha!  An mb3k post!  He was one of the better DIY-er's on Head-Fi, but for some strange reason, he decided to do other things:
 
http://www.modelmayhem.com/484419
 

Yeah, strange... 

 
At any rate I'll see if I can't do some testing with some acryilic sheets I have laying around to see if it will handle me soldering components on it. I'm guessing its going to melt before the solder sets. Worst case, I'll just do it old school with a proper breadboard 

 

 

[MisterX]

Acrylic starts to melt at around 230° (give or take depending on the trade name).
Good luck with that.

 

[Rainmaker91]

  Acrylic starts to melt at around 230° (give or take depending on the trade name).
Good luck with that.

Which is why I'm doing these tests. I'm fully expecting it all to melt in my hands, but I won't know for sure unless I try. I also have different materials I can work with, but I simply want to give a clear PCB a try for the fun of it all 

 

 

[Wiljen]

Try PolyetheretherKetone (Peek) it is a clear thermoplastic that retains its strength up to above 500F.  It is typically used in boiling water applications as it can maintain long term stability even in the presence of high pressure steam at 250C.

 

[Rainmaker91]

  Try PolyetheretherKetone (Peek) it is a clear thermoplastic that retains its strength up to above 500F.  It is typically used in boiling water applications as it can maintain long term stability even in the presence of high pressure steam at 250C.

I'll see what I have laying around, I have quite a bit of different types of scrap left over from other projects. I have Lexan if that will be better than generic Plexiglass, but honestly it doesn't need to be clear (although that would be really cool). I just want something simple so that I can make a nice looking board for now.

 

[Wiljen]

Lexan will melt at about 155C so not a great choice likely as it starts to flow a bit below that.

 

[Rainmaker91]

  Lexan will melt at about 155C so not a great choice likely as it starts to flow a bit below that.

Better than my generic acrylic that melts at 75*c, and the brand name plexiglass that melts at 105*c. Still though I don't think there will be that much of a problem as the temperatures won't be that high. I guess I'll find out when I test it, which I unfortunately didn't get to do today. Oh well, I have some heat resistant cardboard as well but that is 9mm thick... so yeah.