Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › help finding a replacement for C8 of bantamDAC?
New Posts  All Forums:Forum Nav:

help finding a replacement for C8 of bantamDAC?

post #1 of 10
12/20/09 at 3:04am
Thread Starter 
C8 is out of stock at mouser, and I am not really sure what's important with finding a replacement.

can anyone help me out?
C1206C226K9PACTU Kemet Multilayer Ceramic Capacitors (MLCC) - SMD/SMT

Would this work?
GCM31CR70J226KE23L Murata Multilayer Ceramic Capacitors (MLCC) - SMD/SMT

are there a better options?

Thanks in advanced =)

EDIT: I found this:
http://www.mouser.com/ProductDetail/...x%252bP3Fsk%3d
it's the same capacitor with a 10V rating, but it's significantly wider. But, looking at the layout, It seems like length is much more important than width.

Would that work?
Reply
post #2 of 10
12/20/09 at 5:19am
I would have went with this one - cheaper, same specs.
GRM31CR60J226ME19L Murata Multilayer Ceramic Capacitors (MLCC) - SMD/SMT
Reply
post #3 of 10
12/20/09 at 5:40am
Thread Starter 
20% tolerance instead of 10%.

Is that not important? obviously, the BOM doesn't contain the cheaper ones even though their available.
Reply
post #4 of 10
12/20/09 at 6:17am
22uF with 10% is 19.8uF - 24.2uF, 20% is 17.6uF - 26.4uF, considering this is a simple 5V USB power bypass cap, it really doesn't matter all that much. You're putting it in parallel with C7 - big electrolytic.
Reply
post #5 of 10
12/20/09 at 6:33am
Quote:
Originally Posted by FallenAngel View Post
I would have went with this one - cheaper, same specs.
GRM31CR60J226ME19L Murata Multilayer Ceramic Capacitors (MLCC) - SMD/SMT
FallenAngel is correct. The actual spec for the capacitor in that position is anything from 1uf to 22uf, so if the tolerance is 20%, it's not going to hurt. It's also just decoupling the ground from the voltage supply on the USB connection, so it's not really that critical. There's another 1000-1500uf around the same connection, separated by two ferrites.

Get the cheaper one at 20%.

EDIT: Looks like he said the same thing while I was checking the schematic/specs.
Reply
post #6 of 10
12/20/09 at 11:43am
Quote:
Originally Posted by FallenAngel View Post
I would have went with this one - cheaper, same specs.
GRM31CR60J226ME19L Murata Multilayer Ceramic Capacitors (MLCC) - SMD/SMT
I just ordered this one for my Bantam.

If you look at the BOM, IIRC, all the SMT caps at 1206 are from Kemet. Doesn't make the Murata a worse cap, it is just a choice. Just like choosing Vishay-Dale for all the resistors.

I did a BOM once for the GrubDAC where I used the most precision thin film resistors and the best (5%) caps. Took the price of the bom from $20 to $70. You could do the same thing on the Bantam pretty easily.
Reply
post #7 of 10
12/20/09 at 1:59pm
Thread Starter 
Thanks everyone. I appreciate it. I suppose I'll be ordering that cap.

but that makes me wonder.. why -was- kemet chosen.

By replacing all the SMD capacitors by their cheaper alternatives (Murata, Vishay-Vitramon), you can save about $3.

$3 cheaper on the history of all bantam orders is alot >_>. the PCB only costs $2.

Are the kemets suppose to be any better? or should I stop trusting BOM's so much.
Reply
post #8 of 10
12/20/09 at 2:13pm
Every designer/bom maker seem to have a preference for a certain makers part.

A couple of consideration to that:
- maybe a vendor tends to have a certain part in stock. This can make maintaining a BOM simpler.
- maybe you just like a certain part makers product. For example, the Vishay Dales on the BOM are white on black text, not black on blue like the cheaper KOA that will work. Easier to read, therefore easier to support.

There are a lot of parts that will fit the bill. Just depends on what you want to spend, what your preferences are and what your goal of price is.

For example, on the grubDAC, when I did my BOM, my goal was to try and keep the overall price to about the same as the BantamDAC. So I went with the parts that I perceived as the highest quality that kept the total price the same. In my case, I could choose C0G capacitors in a lot of positions instead of X7R or X5R. Does the temperature co-efficient really matter for the DAC? Maybe, Maybe not, but it makes me feel better to spec the parts.

So the BOM is important, but there are always substitutions that can be made. You just need to know which ones can make a difference and which parts cannot be substituted.
Reply
post #9 of 10
12/20/09 at 4:47pm
Quote:
Originally Posted by nullstring View Post
Thanks everyone. I appreciate it. I suppose I'll be ordering that cap.

but that makes me wonder.. why -was- kemet chosen.

By replacing all the SMD capacitors by their cheaper alternatives (Murata, Vishay-Vitramon), you can save about $3.

$3 cheaper on the history of all bantam orders is alot >_>. the PCB only costs $2.

Are the kemets suppose to be any better? or should I stop trusting BOM's so much.
Sorry, but I'm not as patient as cobaltmute. Please note the date of the BOM - it was made on 11/1/2008. Heck, Murata may not have made that cap in 2008, and Vishay may not have even owned Vitramon at the time - that's not even considering the price changes that occur almost monthly in these types of parts. Why not b*tch about Mouser and DigiKey raising their PCM2702 price from $9.86 to $13.59? That has more of an effect on the BOM price than anything you're complaining about.

It's D-I-Y. The ultimate choice of parts is up to you. As it is, I believe the Beezar/DIYForums BOM's are fairly elaborate with a pretty good set of choices. There's a full complement of DigiKey (when stocked) and Mouser choices for each design I support. It also takes a lot of work to put the specific web links in there for each part, too, but that seems to have been backfiring lately.
Reply
post #10 of 10
12/20/09 at 9:34pm
Thread Starter 
erm, I didn't mean to be so offensive...
I apologize.
I do appreciate all the work you guys do.

I have no problem chosing my own parts; It just was never clear to me that was an option. I mean, I created a thread about something in which there were probably hundreds of capacitors that would've worked fine. >_<.
Reply
New Posts  All Forums:Forum Nav:
  Return Home
Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › help finding a replacement for C8 of bantamDAC?