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Old 9th June 2008, 08:04 AM   #11
Electrons are yellow and more is better!
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I recommend to put those caps close the regulator, I mean max 10 mm. The exact value isn't critical but a but cap results in worse step response. 22-100 uF is normal values I'd think.

Tantalum or plastic+ elco and this has to do with impedance versus frequency.
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Old 9th June 2008, 01:20 PM   #12
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Quote:
results in worse step response.
Exactly as I said, Cool

Bypassing reduces damping at high frequencies, so decreases phase margin, thus better step response.

Thank you very much for your advice, P-A!

All the best, Hannes
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Old 9th June 2008, 03:43 PM   #13
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Quote:
Originally posted by h_a
jackh, I just got the quote from the board house and sent you an email!

For all others that might be interested: with 12 boards we already cut the initial price in half, so at the moment it's 9 Euro per board.

All the best, Hannes
Hannes: Suggestion: Please post the price breaks vs quantity.

This will help generate real interest. And you could periodically post what the interest number and price is at that time.

May the PCB also work for some other 3 pin regulators such as lm338?
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Old 10th June 2008, 01:51 PM   #14
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Hi SheldonD, sorry for my late reply, I've been busy!

From a quick look you can use the lm338 also; they have the same pinout. However you would need to bend the leads a bit, since it's a different package (TO-220 vs TO-3P of the LT1083). I will see if you can add some additional pads to the board, but don't get too excited, there's only little space.

Acutally I don't know exact price breaks as I didn't plan for a real large-scale group buy. I need some boards for myself and thought that maybe others would needs some as well, since that kind of regulator boards is rarely offered.

Of course everybody benefits from a lower price as well.

Indeed if there are 1-3 people joining me, I'm happy to order the boards!

Please let me know if you're interested, I want to order soon!

Mail me or post here, I will contact the guys who showed interest regarding payment in the next few days!

All the best, Hannes
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Old 10th June 2008, 02:31 PM   #15
Electrons are yellow and more is better!
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To keep things flowing good, here is reading for you.

Set up a wiki page first and collect the interest, then get an offer from your pcb house, after that create a real list and start to get money from people. If you want some help with the setup, send me a message.

It's very easy to mess up things you see and it may be much money involved. Make sure you charge enough because you have costs for envelopes etc.
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Old 10th June 2008, 03:09 PM   #16
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Thanks a lot for your generous help, P-A!

Indeed for a large group buy a wiki and good book keeping skills are a must

So just to summarize:

Costs

Currently 9 Euro per board, 14 boards total.

Expect for a small number of boards about 5 Euros shipping (worldwide) without personal receipt and 7 Euros with personal receipt; for 8+ boards add about 2 Euros for the increased weight.

Europeans get cheaper shipping, about 3 Euros without and 5 Euros with personal receipt.

I will wait for a few more days, say to the weekend and then I would like to start collecting the cash.

Payment options are Moneybookers, bank transfer or sending me plain cash (if you take the responsibility). Paypal still is not able here to offer their service to people without credit card, so I'm honestly sorry, I cannot offer this option.

I just read prototyping in P-As list: people, be aware that the board was not prototyped. I did my work to the best of my abilities and of course I do everything to ensure its proper functioning, but nevertheless it is not tested. Please only join if you are comfortable with this.

Have fun, Hannes
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Old 10th June 2008, 07:46 PM   #17
Electrons are yellow and more is better!
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It's not a good idea with a non-tested pcb. We have had successful group buys but the boards have also been debugged properly. Why don't you order from Olimex a couple of boards first? People here are used to professional boards in most senses.

My advices:
[list=1][*]Check the design![*]Write pcb name in every layer (but in some layers it can be placed outside the board)[*]Write revision number or letter in every layer[*]It's also a good rule to write the layer name in the layer[*]Correct the silkscreen so all designators are clearly visible when the parts are mounted[*]Check trace widths. Unnecessary thick traces in some places[*]Check drill sizes. > 0.2 mm more than the thickest component pin[*]Check pad sizes (a bit small in some places)[*]Check part dimensions with the pcb symbols[/list=1]
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Old 10th June 2008, 07:52 PM   #18
Electrons are yellow and more is better!
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Quote:
Originally posted by h_a
people, be aware that the board was not prototyped. I did my work to the best of my abilities and of course I do everything to ensure its proper functioning,...
Poll:

Hands up for those who are pros here AND succeed the first shot!

I have succeeded only a few times in 20 years!
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Old 11th June 2008, 06:42 AM   #19
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P-A, you really take care of us!

It's up to everybody to decide for himself. This is a simple regulator board with a handful of parts, so I'm confident about it.

(Honestly I have the impression that a lot of the group buys here are about untested boards, but it is never clearly mentioned.)

Anyway, please understand that I'm not a professional business. I do not offer a commercial product. I just offer the possibility to get some boards that I would have ordered anyway.

I highly respect your attitude and your efforts to provide highest quality boards, P-A. However if I have to order prototypes first, assemble and test them and offer boards then, it costs a lot of time and money (prototypes), so I would have to charge these additional costs, even if I don't charge my working time. And who wants to pay that?

You will be astonished, P-A when you will see my Cello pcb buy. Much more complexity! But I'm now working on it for a couple of months now and I'm again confident that it will work Will this be the road to perdition? We'll see

Of course I will extensively check the boards prior to sending them to the board house, including checking all used part libraries, schematic, pinouts...

Quote:
I have succeeded only a few times in 20 years!
Well, you don't do simple boards, do you?

Thank you for all your tips, they will not be forgotten.

All the best, Hannes

Quote:
Check trace widths. Unnecessary thick traces in some places
Now that completely escapes me. What's the disadvantage? I can only imagine that they're harder to solder? An updated artwork did already consider this
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Old 12th June 2008, 07:12 AM   #20
Electrons are yellow and more is better!
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Quote:
Originally posted by h_a
(Honestly I have the impression that a lot of the group buys here are about untested boards, but it is never clearly mentioned.)
Quite the opposite, most boards are excellent when it comes to bugs. I think we have created here a sort of professional way of doing group buys but we have had also a couple really embarrassing ones too so I see it as my duty to eliminate bad offers and bad administration.

When you mention money, prototyping costs will be charged from the buyers so the golden rule if you read my instructions is not to put money into it and also do a prototype run if you plan to make many boards. This is why you have a wiki with the interest. If yo have 100-200 or more boards, you don't order them without a prototype run. I wouldn't do it. Even a simple board can fail in to process. Personally I wouldn't offer boards with irritating bugs. My goal is "spitzenklasse" within the design goal.
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