Official Felix board/kit group buy thread

whubbard · « **Reply #40 on:** 13 Mar 2008, 04:45 pm »

Well here is the last email I received from coilcraft. It seems like there not really even sure...

Quote from: CoilCraft

Hi West,

I'm sorry, but I believe I answered your question to the best of my understanding.
The application notes I had attached should answer any questions regarding how to select the appropriate common mode choke,
and the question "How important is the differential mode choke?" is really a judgment call by you. Often, experimentation is required to answer this type of general question. If you have a prototype circuit, perhaps you could try some samples of different products.

Best Regards,
Chris

Seems like its going to be trial and error for us. I read the notes (the pdf files I linked too), and I didn't pick up on when to use a differencial choke, but I guess I will read them again.

I'm still waiting on a reply from miller...

EDIT:
here are some things I picked up from the notes.

Quote from: CoilCraft

Neglecting measurement error (approximately 4 decibels),
the differential input did not appear to affect the
common mode attenuation of the circuit even at high
frequencies (through 10 MHz).

From my reading I would say that the differential mode is not very important to our application, however, higher inductance is!

I will continue on in my search, but inductance seems like the big factor.

Occam · « **Reply #41 on:** 13 Mar 2008, 06:06 pm »

Quote from: whubbard on 13 Mar 2008, 04:45 pm

...
EDIT:
here are some things I picked up from the notes.

Quote from: CoilCraft
Neglecting measurement error (approximately 4 decibels),
the differential input did not appear to affect the
common mode attenuation of the circuit even at high
frequencies (through 10 MHz).

From my reading I would say that the differential mode is not very important to our application, however, higher inductance is!

I will continue on in my search, but inductance seems like the big factor.

I believe you are misinterpreting the Coilcaft quote. The differential signal they are referring to is nominally your mains voltage. They are simply saying that if you measure the common mode attenuation with no other signals present, it will track (within 4db, at the same frequencies and impedances/loads?) the same common mode attenuation with your mains power doing its sinosoidial hokey pokey simultaneously.

FWIW,
Paul

whubbard · « **Reply #42 on:** 13 Mar 2008, 06:30 pm »

I'm not surprised, as I'm new to this whole thing, I'm really just trying to do my best to figure this all out.
I still feel that the inducatnce is much more important than the differential filter, but it might ultimietly depend on your personal power interference.
My main theory for this is because as I previously quoted common chokes usually reduce 90% of the noise, so if you sacrifice the quality of the common choke, you sacrifice more than if you don't have the differencial mode choke.

Paul,
do you by any chance have any insights into this subject?

BradJudy · « **Reply #43 on:** 13 Mar 2008, 06:56 pm »

It looks like the 8113's might make the first level discount after all - I just received another order that included several of them.

The complexity is starting to ramp up as the late orders trickle in. We're now up to six countries on four continents, so I need to better understand international shipping options. I have already received some pointers from one of the international members, so that helps.

BradJudy · « **Reply #44 on:** 14 Mar 2008, 07:16 pm »

Please read this note

This is a group buy and only a group buy. That means that I am aggregating purchasing power to get discounts on components and a PCB board designed with community feedback (an item that would otherwise be financially impractical). I will not be providing support for these items. Only buy them if you know what you need and what to do with them. Some of the questions I am receiving imply to me that I will be getting support requests once these ship.

When I send out invoices, I will include a reminder that no support is provided and that buyers need to know how to implement these and how to do it safely.

Thanks,

Brad

BradJudy · « **Reply #45 on:** 15 Mar 2008, 12:27 am »

Things have been busy with PM's today. I need to get some replies in. It looks like we're sitting right about 300 boards total with about 200 sets of capacitors (remember that means 1200 capacitors) and slightly fewer than 200 CMC's.

I need to figure out how to deal with additional costs (bags, boxes, etc) in terms of the pricing. It will probably be a flat-rate line-item and will fit under the buffer for extra discounts, so your end costs should still be lower than expected.

US residents will probably get theirs via FedEx ground and international (now up to 8 different countries) residents will probably get theirs via USPS.

Hopefully I'll get invoices out this weekend, once I do some math on end costs.

nature boy · « **Reply #46 on:** 15 Mar 2008, 01:22 am »

Brad,

Thanks for arranging this group buy and for all the number crunching. Make sure to cover all
your costs adequately. This is a helluva nice thing you are doing for your fellow AC'ers.

NB

whubbard · « **Reply #47 on:** 15 Mar 2008, 03:02 am »

Considering the volume that is being ordered, what do you all think about all splitting the cost of Brads filters. Considering the amount of work he is doing for us, it would be a nice for all of us to return the favor.

What do you all think?

Christopher Witmer · « **Reply #48 on:** 15 Mar 2008, 04:00 am »

Brad should round up his prices in a manner that leaves him ahead of the game on paper. I'm all for it if he ends up getting his components for "free" (which they won't be, even if they are). There is so much work involved in this at his end that any modicum of rounding up on the prices would not even begin to cover the amount of time he's putting into it.

And folks, this forum ought to be able to provide all the technical support that anyone needs. We should have a rule that the first person who asks Brad for technical support gets instructions on how to wire the thing so it delivers a massive jolt of electricity the first time it's plugged in. (That was humor, by the way.)

-- Chris

P.S. Here's the first technical support question: "Which end of this soldering iron am I supposed to grip?"

BradJudy · « **Reply #49 on:** 15 Mar 2008, 04:06 am »

Don't worry too much about me. I'll make sure the costs of the prototype batch are covered as well as all packaging expenses. In the end, I'm getting a bulk discount too.

Quote from: Christopher Witmer on 15 Mar 2008, 04:00 am

P.S. Here's the first technical support question: "Which end of this soldering iron am I supposed to grip?"

Don't think I haven't made that mistake before - it hurts!!

tanchiro58 · « **Reply #50 on:** 15 Mar 2008, 04:28 am »

Quote

P.S. Here's the first technical support question: "Which end of this soldering iron am I supposed to grip?" Very Happy

Don't think I haven't made that mistake before - it hurts!!

One more question: " Which end is a positive end in a film metallized cap?"...

whubbard · « **Reply #51 on:** 15 Mar 2008, 04:32 am »

Quote from: Christopher Witmer on 15 Mar 2008, 04:00 am

Brad should round up his prices in a manner that leaves him ahead of the game on paper. I'm all for it if he ends up getting his components for "free" (which they won't be, even if they are). There is so much work involved in this at his end that any modicum of rounding up on the prices would not even begin to cover the amount of time he's putting into it.

Agreed.

Brad, make sure you do this!

Christopher Witmer · « **Reply #52 on:** 15 Mar 2008, 06:23 am »

Quote from: tanchiro58 on 15 Mar 2008, 04:28 am

One more question: " Which end is a positive end in a film metallized cap?"...

That reminds me of the time I got yelled at by the boss of my construction crew for throwing away all the nails that were pointy on the wrong end -- imagine how sheepish I felt when he explained that those nails were intended for use on the other side of the house. Anyway, I'm sure everything will be much better now that I'm working with AC, which is pointy on both ends.

BradJudy · « **Reply #53 on:** 15 Mar 2008, 04:27 pm »

Okay - the group buy is closed. Everyone who has sent me a PM is in and will receive an invoice this weekend. After receiving their invoice, everyone has one week to pay.

In the end, between boards, caps and CMC's there are more than 2000 pieces to be ordered from five vendors and shipped out to just over 50 people around the world.

Thanks for participating and hopefully everything goes well.

BradJudy · « **Reply #54 on:** 15 Mar 2008, 05:29 pm »

Now for the really good news....new prices:

PCB boards: $5 each (down from $9/$7)
F1778 X2 caps: $6 a set (down from $6.50)
MKP 338 X1 caps: $6.50 a set (down from $9)
(All CoilCraft items stay the same)
8117-RC: $8 each (down from $9)
8113-RC: stays $7
8118-RC: $8 each (down from $9)

These costs still cover the development boards and are rounded up a bit to cover PayPal fees, bags, boxes, etc.

Because these prices may change some plans, I'll allow only those who have already placed an order to increase their quantities if they wish. Only over the weekend If I send you an invoice before you decide to change your order, I can send a new one.

I'll look into shipping costs and may just go with a flat-rate inside the US if there isn't too much variation of costs.

nature boy · « **Reply #55 on:** 15 Mar 2008, 07:28 pm »

Smokin' great prices on the group buy!

Thanks again Brad.

NB

BradJudy · « **Reply #56 on:** 16 Mar 2008, 09:22 pm »

Invoices have gone out to all US buyers.

I still need to figure out shipping costs for international buyers, but your invoices should come tonight or tomorrow.

BradJudy · « **Reply #57 on:** 17 Mar 2008, 03:14 am »

The Canadians now have their invoices.

Seven more left, but those will have to wait for tomorrow for me to stop by the post office and check into the options.

Christopher Witmer · « **Reply #58 on:** 17 Mar 2008, 11:08 am »

Quote from: BradJudy on 17 Mar 2008, 03:14 am

The Canadians now have their invoices.

Seven more left, but those will have to wait for tomorrow for me to stop by the post office and check into the options.

Take your time, at the rate the dollar is circling the drain, I could get these babies for free . . .

"Zero . . . it's what's for dinar."

-- Chris in Tokyo

kyrill · « **Reply #59 on:** 17 Mar 2008, 11:14 pm »

low dollar's value will enhance American Sellings
I really worry now how Airbus can keep Boeing at bay
( is that the right expression?)