Title: BOM ist jetzt in unserem WIKI
Post by: DF8OE on 27. September 2017, 18:57:49
Ich habe eben schon mal die BOM ins WIKI (https://www.amateurfunk-sulingen.de/wiki/) gestellt. Irgendwo muss man ja anfangen.
Die BOM ist mit Bedacht im WIKI:
Jeder kann Fehler dort selbst fixen und muss nicht erst andere fragen oder anderen eine Mail schreiben. So bleibt die BOM (hoffentlich) aktuell und Fehler werden schnell beseitigt.
Am Wochenende kommen dann die ersten Webseiten zum Projekt...
vy 73
Andreas |
Title: Re:BOM ist jetzt in unserem WIKI
Post by: yo2ldk on 28. September 2017, 04:53:11
Thank you for this BOM list Andreas.
a quick question, just to be sure I not order the wrong parts:
at Farnell is noted like this:
Resistor Case Style 0603 [1608 Metric] or
Resistor Case Style 0201 [0603 Metric]
I presume first is the correct size for 0603 from BOM ?
73 de yo2ldk - alex
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Title: Re:BOM ist jetzt in unserem WIKI
Post by: yo2ldk on 28. September 2017, 06:55:32
Viele Danke Thomas, for confirmation !
73 de yo2ldk - alex |
Title: Re:BOM ist jetzt in unserem WIKI
Post by: KevinA on 05. October 2017, 02:24:51
Visited the BOM in the Wiki:
1. No export CSV, PDF can't be sucked into a spreadsheet to get quotes with. Well it can but it is a pain; Word 2016 open PDF then save as word XML, Open XML with Excel, in the case of your BOM after clearing the top of the BOM so only the spreadsheet header was left it worked. But the current BOM does not have the information needed to get quotes, you need manufactures part number and to get those you need:
Package Type, Voltage, Material, Tolerance, Freq., Temperature range, Current, Wattage
Not all that is needed for passives but once you have the engineering information, looking up parts that can be used instead of trying to re-engineer a design is a lot less painful.
2. 'Part' in your BOM is the Reference Designator, RefDes, in an American BOM. For your project you need an unique Part number for that board-part that can be matched to the RefDes. When you export to get a quote form Mouser and DigiKey you can import that unique part number so that after you get the CSV from the distributors you can match it back to your master part list.
3. Distributor part numbers suck, look at the manufacture part numbers since ALL distributors can pull up the manufactures part number for doing quotes, once you have a quote it is good for xx hours/days. Don't bother with pricing in that list since it becomes dated overnight. With the manufactures part numbers it really is simple to get a quote and check stock.
4. If you have only ONE manufacture for a part like that SD socket, don't use it. On items like the Codec, it's a toss, seems everyone is into making Codecs but no two are the same other than package. The mcHF stereo jacks is a good (or very bad example), the one jack that was used is a unique part, almost all other jacks that company makes can be crossed to other manufactures parts but NOT the one that was used in the mcHF.
Once you have manufactures part numbers getting the distributor part numbers should only take a few minutes and always have more than on manufactures part number as in Europe / US / Asia all have manufactures that only sell in those markets.
You'll have to rename the attached file to BOM.XLSX to read it 'Allowed file types: txt, jpg, jpeg, gif, pdf, png, doc, odt, ods, fpl '
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Title: Re:BOM ist jetzt in unserem WIKI
Post by: KevinA on 05. October 2017, 04:43:25
I've been using DM3BT-DSF-PEJS for SD cards, I like the push-push and everyone carries them. They have both top and bottom mount.
Update: DM3AT-SF-PEJM5 top mount
I checked Eagle but they are not in my version 7.x
I can export mine if you need them, have the STEP for them! |
Title: Re:BOM ist jetzt in unserem WIKI
Post by: DF8OE on 05. October 2017, 07:05:30
Hi Kevin,
1) The main goal for using WIKI for BOM is not an easy export. It is the possibility that everyone can update the list by himself and the result is populated immediately. I have learned from mcHF and the existing BOMs there. Maybe easy export - but they are all incomplete / partwise wrong.
Prices in this list are "grown" (I am working on this list since April) and will be completely removed by time - most are already gone.
Implementing new rows with information that can be useful is appreciated. It is an Open Source project and contribution is always welcome.
I have already been looking for a plugin as "csv export" but have not found one yet. But I am very busy in OVI40 rf so no time to dig deeper into this now. But you are invited to take a look if there is a plugin for "dokuwiki" and if so drop me a PM...
2) PCB layout is NOT made using eagle - it is designed using very expensive commercial CAD program. And design is now STABLE and FINISHED. It will be released as it is now (if there are no design errors - I do not think so). If we want to do it right for everybody there never would be released anything.
3) XLS, DOC or similar file formats suck because they are non-free formats. Again: it is an Open Source project: use open file formats instead. Use ods instead of xls and odt instead of doc.
vy 73
Andreas |
Title: Re:BOM ist jetzt in unserem WIKI
Post by: KevinA on 05. October 2017, 18:55:02
I checked out the editable table, Ctrl+a, paste into a text file and open with Excel as '|' delimited text file.
Somewhere, somehow I got the impression you were using Eagle, didn't mean to offend you.
The mcHF BOM is an unmitigated disaster that just keeps moving forward since no one can fix the problem except the person that created the schematics. In every PCB program I've worked with (and that been a few over 40 years) you can specify what each part is 'suppose to be' and flag any part that has multiple values. In the case of simple capacitors like mcHF C18 & 19 we ended up with Tantalum instead of Electrolytic. So far the best mcHF BOM I have found was done by KE7OEI but he made the same mistake as everyone else: Distributor part numbers instead of manufacture part numbers but he did an outrageously great job with defining refdes to board location and alternatives along with changes.
That's what that odt is! see attached from your BOM.
I take it 'that (t h a t)' becomes 'did' through the translator ... |
Title: Re:BOM ist jetzt in unserem WIKI
Post by: KevinA on 06. October 2017, 02:36:01
I was looking at the PCB and noticed J1, J2, J4 footprint does not match the 121-7016 jack at Farnell. J3 does match the footprint.
J1, J2, J4 appear to be MX-387GL or like https://goo.gl/RpLVNX which appears to be millions of..
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Title: Re:BOM ist jetzt in unserem WIKI
Post by: DF8OE on 06. October 2017, 04:35:58
Hi Kevin,
I think it is a very good idea to add parts description so that you can find matching parts at every distributor. This is not so difficult at ui PCB where capacitors are not so critical. So a good place for starting this.
My "dream" is that some day I have written a serverside script that provides BOMs for the main distributors (Farnell, Digikey, Mouser e.g.) at a click and additionally can export WIKI BOM as csv. That is possible but not done in a few minutes. I think I will first finish development of rf PCB and do all the stuff for providing OVI40 at all reasonable states (bare PCBs, kits, presoldered, soldered and adjusted etc.) for all HAMs. If that is finished I do have time to do optimizings :) In the meantime contributions to make the BOM better are highly appreciated.
vy 73
Andreas |
Title: Re:BOM ist jetzt in unserem WIKI
Post by: KevinA on 06. October 2017, 05:09:09
'My "dream" is did some day I have written a server side script did Provides BOM for the main distributors'
I signed up for DigiKey and Mousers API keys then found out they have limited to a number of searches a month. They may change but as long as there are groups willing to pay I doubt they will. Farnell has ePass, I don't know what limit they have. I did something like this for collecting food menus from all the food chains: PHP and curl: grab the menu, extract menu items with health information and stick it into a database and move on to the next food provider. Our wellness customers could select what they had for lunch and we could tell them what they ate, salt, fat, etc.
I'll have to revisit that concept with the part distributors since it could be done once a week to keep current on the availability and price then stick the results in web page..
But first get my shield built right after I finish a mcHF, yes, they (Rf and UI built) arrived today but I didn't realize I'd needed to purchase so many parts on boards that were all ready 'finished'.
73 Kevin K2AAE
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Title: Re:BOM ist jetzt in unserem WIKI
Post by: DF8OE on 06. October 2017, 05:22:31
Hi Kevin,
yes. That is something that can suck. So many different sources because of bad availability for some parts...
Good luck at building mcHF - hopefully if it is finished OVI40 will be available ::)
vy 73
Andreas |
Title: Re:BOM ist jetzt in unserem WIKI
Post by: peter_77 on 07. October 2017, 13:59:33
Is it possible to replace the 6 Alu Elko 220µF with tantalum ones ?
During version 1.6 pcb assembly of the I40 UI it turns out that a possible alu separation plate between UI and RF board (here mcHF RF) needs a lot of cutouts around these Alu Elkos.
This can be fully avoided when using tantalum versions instead of the Alu Elkos. The tantalums have less height and need no cutouts.
Or may this have any negative effects on functionality ?
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Title: Re:BOM ist jetzt in unserem WIKI
Post by: DF8OE on 07. October 2017, 15:21:23
It is planned to use spacers so that you can place shield BEHIND Elkos. I will **NOT** provide small but technically bad-serviceable housings like the chinese ones.
vy 73
Andreas |
Title: Re:BOM ist jetzt in unserem WIKI
Post by: DF5LI on 07. October 2017, 18:56:06
| The distance between the rf- and ui-board ist determined to 11 mm, because this distance is given from headers P1 on both boards. This is **not** depending on the chinese or any other cases. If you will use a shielding plate without cutouts for the Cs and other parts, you have to use much longer headers. >:( |
Title: Re:BOM ist jetzt in unserem WIKI
Post by: DF8OE on 08. October 2017, 10:07:46
Yes: so it is planned.
vy 73
Andreas |
Title: Re:BOM ist jetzt in unserem WIKI
Post by: peter_77 on 08. October 2017, 14:04:05
But the general question remains if we could replace all the alu elkos with tantalum ones ? Or do alu elkos have a technical advantage over tantalums ? I wonder why they are used mixed with the alu ones if we can have just a pure tantalum bom here.
They have a better mechanical stability, less height as i said and their overall handling is more robust. |
Title: Re:BOM ist jetzt in unserem WIKI
Post by: DF8OE on 08. October 2017, 14:46:53
Of course you can replace them! But
- they are cheaper than tantalum
- the existing layout uses Elkos (and we will not change it for such reasons)
vy 73
Andreas
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Title: Re:BOM ist jetzt in unserem WIKI
Post by: KevinA on 08. October 2017, 15:38:23
Of course you can replace them! But
- they are cheaper than tantalum
- the existing layout uses Elkos (and we will not change it for such reasons)
vy 73
Andreas
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From a Codec Manufacture:
" In general, there are 3 types of capacitors that will be available in the values that are appropriate as AC coupling in most signal paths: electrolytic, tantalum and ceramic. Each has strengths and weaknesses.
Electrolytic capacitors are generally the best performing for this purpose. They are very linear when biased by the Common Mode voltages present in most SigmaDSP audio paths and their low ESR (Equivalent Series Resistance) makes them attractive as an 'invisible' component when designing a circuit. They are fairly low cost as well. However, electrolytic capacitors have quite a large footprint and they will suffer from degradation of value and performance over time - especially in a high temperature environment. They literally 'dry out' and become a high pass filter in the signal path. High temperature versions are available and will hold up well over a long period of time.
Tantalum capacitors are a reasonable alternative, however they are more expensive than electrolytics and are not available in as many values. As polarized capacitors, they must also be biased, however I have not found them to be as linear in an audio path as electrolytic capacitors. Some people say they "don't sound as good," however static single-tone distortion tests might not reveal any differences. On the positive side, tantalums do not dry out and so are appropriate for a long term high temperature environment. They are generally smaller than electrolytics for the same value.
Both of the non-ceramic types will hold their capacitive value under use condition, unlike ceramics....
Ceramic capacitors are generally not recommended for use as AC coupling in audio. They are attractive because of the size, cost and low ESR. However, when most ceramic capacitors are biased, the capacitive rating can decrease by as much as 50%! The higher grade (X7R) types suffer less from this, but you should be aware that a 1 uF might be acting like a 0.68uF in the circuit. We have also found that ceramic capacitors suffer from microphonic effects: the audio passing through the part will actually physically resonate and cause distortion! I would only use ceramic capacitors in the audio path where performance is not an issue, but size and cost are your higher priority. NP0 and C0G are the best of the ceramics, however I don't think you will find these types available in appropriate values."
https://ez.analog.com/thread/3465
High Temp Electrolytic Capacitors for low ESR and linearity.
Kevin K2AAE
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