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Old 4th April 2013, 12:13 PM   #101
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Amperage,

For proper ferrite beads implementation check this out:
http://s3t.it/data/uploads/dac_1541_v011.png
(at least i think it is proper way)

The 20v connector on the left - all the conductors pass thru ferite beads, GND and supply wires, and there is a ground fill cutout around "dirty" side - so the RF won't go to the board thru parasitic capacitance.
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Old 4th April 2013, 02:37 PM   #102
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Quote:
Originally Posted by s3tup View Post
Amperage,

For proper ferrite beads implementation check this out:
http://s3t.it/data/uploads/dac_1541_v011.png
(at least i think it is proper way)

The 20v connector on the left - all the conductors pass thru ferite beads, GND and supply wires, and there is a ground fill cutout around "dirty" side - so the RF won't go to the board thru parasitic capacitance.
Looks good.. Your design?

I have ferrites on every line except the power ground currently (ran out). I have more suitable ones on the way here that work better around the 1ghz mark along with a bunch of those X2Y caps in 22pf, 100pf and 0.1uf.

Got the 100pf for peak performance around the 800-900mhz range and the 22pf extends nicely up to around 2ghz. The 0.1uf X2Y's will decouple the op amp power coming in from the 2mhz DC/DC converter to clean up any stray noise from that. I'll have a decade capacitor arrangement using normal ceramics along with the 0.1uf X2Y to help smooth things out a little more(1uf and 10uf).

I also ordered some teeeeeny carbide drill bits and some press in vias (ugh) to make stiching the ground planes together a bit more tolerable. Won't have to hand solder small bits of wire through each. I really need to setup something to plate my drilled pcbs
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Old 4th April 2013, 06:33 PM   #103
marce is offline marce  United Kingdom
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some possibly usefull links:
http://www.compliance-club.com/pdf/EMCTestingPart1.pdf
http://www.compliance-club.com/pdf/EMCTestingPart2.pdf
http://www.compliance-club.com/pdf/EMCTestingPart3.pdf
http://www.compliance-club.com/pdf/EMCTestingPart4.pdf
http://www.compliance-club.com/pdf/EMCTestingPart5.pdf
http://www.compliance-club.com/pdf/EMCTestingPart6.pdf
http://www.compliance-club.com/pdf/EMCTestingPart7.pdf
EMC Design
Design Techniques for EMC
Design Techniques for EMC: cables and connectors
EMC Compliance Club – Design Techniques for EMC. Part 3 — Filtering and Suppressing Transients.
Design Techniques for EMC - part 4
PCB DESIGN TECHNIQUES FOR LOWEST-COST EMC COMPLIANCE
Design for EMC Part 6: ESD, dips and dropouts, etc.

A lighter view, even though it mentions emissions the reverse is true.
The 10 Best Ways to Maximize Emission from Your Product

These devices get used a lot, especially where radio transmissions are used.
ACH32C-103
Put the name in google and you'll get the data sheet, the central GDN connection is connected either directly to the board GND, or on an isolated plane joining the main ground through a larger ferrite, both schemes get used and both work. Also sometimes they get used together, more delicate signals requiring the standard GND, power and more robust using the "dirty ground". These devices are also often used in conjunction with some ESD protection, to avoid nasty spike from the user when they plug something in or out.

Last edited by marce; 4th April 2013 at 06:49 PM.
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Old 4th April 2013, 07:30 PM   #104
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It's a problem making good doublesided boards at home. I still make them, they have their place, but you just can't do as good a job as a PCB manufacturer unless you're prepared to virtually become a PCB manufacturer.

You can get 10 off 50*50mm boards delivered in ~10 days for $10 + postage from seeedstudio.com. Look under 'Services'.
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Last edited by counter culture; 4th April 2013 at 07:33 PM.
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Old 4th April 2013, 07:34 PM   #105
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Originally Posted by counter culture View Post
You can get 10 off 50*50mm boards delivered in ~10 days for $10 + postage from seeedstudio.com. Look under 'Services'.
$10 really? How can they afford that? Most places charge around $75 or so setup fee and to get to a reasonable cost per board you have to order 100+.

For troubleshooting and small modifications 10 day turnaround is still pretty annoying but $10.. that's cheap!

On the plus side I've got this LTE RF noise down to a dull roar so I think once I get my X2Y parts in and redo my layout for them I should be pretty solid.

Last edited by Amperage; 4th April 2013 at 07:53 PM.
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Old 4th April 2013, 11:15 PM   #106
agdr is offline agdr  United States
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Quote:
Originally Posted by Amperage View Post
$10 really? How can they afford that?
It is true. I had the board below made at iTeadstudio a couple of months ago. The pricing is similar to Seeedstudio and I think the two may use the same board house. Great quality. I paid $19 for 10 pieces of 80mm X 100mm boards (1.6mm, HASL, 2 layer, green), regular $24, a special they had going during the Chinese holiday. Then $20 DHL from China. The 4 day shipping cost more than the 10 boards. PCB prototyping
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Old 5th April 2013, 06:31 AM   #107
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It is true. I had the board below made at iTeadstudio a couple of months ago. PCB prototyping
that's a handy looking vise you have there. did you modify another product or It came like that?
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Old 5th April 2013, 06:58 AM   #108
qusp is offline qusp  Australia
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i'm not sure I would say its great quality, but its certainly very good for the money. if I was doing something for production I wouldnt use them, the screen printing and soldermask can be a little less than perfect sometimes and i'm not 100% sure they do 100% E-test/flying probe testing; but hey its $10!!. or even try seeed, which have the same $10 deal, plus $39 for 4 layer!! which may use the same boardhouse, but they seem to have even better deals. is it iTEAD that includes shape routing in the cost?

some of these services arent quick though, usually up to a few weeks, so doing stuff at home is better if you need to do a one off quickly, or perhaps a larger board, but really there is little reason to do a second generation board at home anymore

I say again $39 for 10 x 4 layer PCBs!!

Last edited by qusp; 5th April 2013 at 07:05 AM.
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Old 5th April 2013, 08:00 AM   #109
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Yeah definitely worth it.. Once I get my final component list I'll probably do a 4 layer layout and get the 10 for $39 deal. I wonder if they allow you to panelize like iTead to squeeze more boards in for the size. the boards will end up being something like 80mm x 21mm so I could fit 4 boards in to a 10cmx10cm area.
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Old 5th April 2013, 08:32 AM   #110
qusp is offline qusp  Australia
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you can panelize, but you have to cut them yourself. the $39 is for 50 x 50mm. if you actually need or want to panelize to 10x10cm and get 40 PCBs once youve cut it, you would need to add 50 bucks for $89. If 20 is enough, just get the $69 for 10 pieces of 10 x 5cm. since you are going for as good HF decoupling as you can, I recommend going with the thinnest PCB, which is 0.8mm. not as sturdy if that worries you, but decoupling is more effective, as is signal->ground closer and thus better.
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