| h_a |
Hi folks,
I'm finishing a pcb-layout for a voltage regulated psu-board for dual rails (like +/-35V) which uses the LT1083/LT1084/LT1085 regulator (the high power (7 A) TO-3P variant) for both polarities. I'm going to power my power amp with it.
It is very small in size, currently 50x70mm, double sided, has very fat tracks (150mills for the regulated side), has well separated tracks (20mills average track clearance) and will be manufactured with heavy copper (70um).
One board gives both voltages (adjustable from +/-1.25V up).
This is the first time I'll order at this boardhouse, but I've heared the board edges are cut - not milled - so probably don't look that perfect as you're used to. However this does not have an impact on functionality (just looks).
Big advantage - they're cheap.
Cost depends on number of boards, rough guess is about 18 Euros per board for 4 pcs (that I need), of course dropping with every board that comes in addition.
I'm looking if there's interest, so we could order more boards and benefit from a lower price.
Have fun, Hannes
PS: I will post schematic and layout in the next few days. |
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| h_a |
Schematic
Please note that caps on the regulated side are necessary and that I did not provide space on the pcb for them. They should be mounted on the amp board anyway, so that they're close to the load. |
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| h_a |
Board
To be able to choose a suitable heatsink depending on the load, I think it's most comfortable to use an external heatsink, off-board to be flexible. So you can use something small for your preamp, but a real chunk of alu (1-2 K/W) for your power amp.
To be able to use thick or multiple cables I used the dual Molex-connectors in parallel for the outputs, so to get lowest resistance. For the ground connection I use a soldered connection.
Maybe some cosmetic changes are left to be done, but otherwise that's it.
I'm happy about every comment on improving it further!
Feel free to mail me directly if you're interested (or post here).
Have fun, Hannes |
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| jackh |
| Count me in for 8 boards |
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| h_a |
Hi!
That's great, so we already have a nice number. I'll quote the board house today and see what they say.
All the best, Hannes |
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| 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 |
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| agent.5 |
I am interested. Have you considered:
[1] adding a protective diode between Vin and Vout?
[2] Maybe another diode parallel R1, and R2?
[3] Maybe space for a small cap (say 1000uf) after Vout? |
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| h_a |
Hi agent.5,
yes I've considered all your points; the diodes are not necessary for this regulator as it has an internal diode (capable of handling microsurge currents of 50A to 100A!). You can check this in the datasheet :D
2 reasons I didn't add a Vout cap: first this cap should be close to the load, preferable without parasitic wire resistance in between. 2nd there's simply no space! The size is fixed and you can see there's simply no space left! I would also have added the option for using the dual as 2 single rails, but same story.
If you're still interested, just let me know!
Have fun, Hannes |
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| peranders |
| quote: | Originally posted by h_a
2 reasons I didn't add a Vout cap: first this cap should be close to the load,.... |
No quite :att'n: If you read the datasheet you'll need a minimum required capactiance _close_ to the regulator. I can read 10 uF tanalum but in your case I would choose 10-100 nF/63 V polyester/ceramic plus 10-22 uF 63 V electrolytic cap. |
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| h_a |
Hi P-A!
Of course! That's the reason I use 2x 15A molex connectors in parallel for the outputs, to get the parasitic resistance to a minimum. Mentally I just add the cabling to the ESR of the cap, which is higher than some centimeters of wire anyway.
From reading the datasheet it is for me unclear why you want to use a bypass, since a 22uF Tantalum or 150uF elco gives perfect stability (as the datasheet says under all conditions). AFAIK Elcos have a rather weak high frequency response, so depending on the regulator this could be needed.
Maybe you could give me a hint on this?
Thank you very much, Hannes |
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| peranders |
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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| h_a |
| quote: | | results in worse step response. |
Exactly as I said, Cool :D
Bypassing reduces damping at high frequencies, so decreases phase margin, thus better step response. :idea:
Thank you very much for your advice, P-A!
All the best, Hannes |
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| SheldonD |
| 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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| h_a |
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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| peranders |
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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| h_a |
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 :D
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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| peranders |
It's not a good idea with a non-tested pcb. :no: 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:
- 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
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| peranders |
| 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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| h_a |
P-A, you really take care of us! :D
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 :D Will this be the road to perdition? We'll see :spin:
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 :D |
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| peranders |
| 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.)
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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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| h_a |
| quote: | | If yo have 100-200 or more boards, you don't order them without a prototype run. I wouldn't do it. |
Currently we're at 14 boards total and I don't think that will increase. I never wanted to reach much larger numbers.
P-A, I have the continued impression you think I'm a complete fool.
It is your right to think so, though I'm wondering what gives you this impression as I clearly commented each and every step to show the contrary.
Honestly I'm finally fed up now. If you would have read my posts fully, you would know that I just want to give some people the opportunity to get some extremely simple regulator boards, which are quite unique in the sense that they are designed to power a power amp. Something like this I have not seen offered here before. Small quantities for a few people.
At first and foremost I need them for myself. And I do have a strong interest that they work right from the start. And I am perfectly sure a less than 20 parts board is routinely done without a prototype.
As I'm routing manually I continously check the design against the schematic, of course there is forward- and back-annotation, and in addition (after another final schematic check) at least 2 full checks of all used part libraries are on my quality control. And I'm confident that this will give me soon flawless boards for a much larger project.
Dear P-A, I'm sorry, I know you as a highly reputable person so I try hard to think that you just want the best for everybody here.
As already said above, I'm fed up. You even openly insult my work without reason.
Folks, I'm sorry, this thing is over now.
The ones that showed interest I will mail directly and if you're still interested you will of course get your boards as I stand by my offer.
Have fun, Hannes |
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| h_a |
Update
I just stumbled over Per-Anders own Group buy PSU-board thread, see here
http://www.diyaudio.com/forums/show...threadid=117036
There he does not mention obeying his rules, nor prototyping. In fact the word prototype can not be found in that thread.
Now I know why I'm treated like this. The group buy of ACDs PSU-boards - where Per-Anders is also involved - has too few orders! Too little interest.
So what to do if somebody else with an alternative shows up? Get rid of him!
What a shame.
Nevertheless people, have fun! Hannes |
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| peranders |
| quote: | Originally posted by h_a
Update
I just stumbled over Per-Anders own Group buy PSU-board thread, see here
http://www.diyaudio.com/forums/show...threadid=117036
There he does not mention obeying his rules, nor prototyping. In fact the word prototype can not be found in that thread.
Now I know why I'm treated like this. The group buy of ACDs PSU-boards - where Per-Anders is also involved - has too few orders! Too little interest.
So what to do if somebody else with an alternative shows up? Get rid of him!
What a shame.
Nevertheless people, have fun! Hannes |
Only you can deside if the interest is enough or not. I'll agree that 14 boards is more or less a prototype run but not 100.
As long as an design is considered free (the level of art is low) I see no problem with that somebody else run the same groupbuy. It's not to get rid of somebody.
So, Hannes, carry on :nod: |
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| h_a |
Hi P-A,
I might be a very odd fellow, but for me audio is a hobby. It's recreation. It's fun.
If I happen to go into a direction where people start to fight eachother and forget that this should be fun, I go somewhere else.
I want to simplify my life. No interest in bad feelings in my hobby.
No further group buy.
All the best, Hannes |
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| peranders |
Audio is also a hobby for me although the knowledge I have has been useful lately.
(In my lab there is a Labgruppen 10 000 W power amp, 10 kg, 2 U high, 19" wide :nod: :drink: :yummy: :lickface: it is used as a bipolar power supply) |
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| peranders |
| quote: | Originally posted by h_a
...get some extremely simple regulator boards, which are quite unique in the sense that they are designed to power a power amp. Something like this I have not seen offered here before. |
This has been done before when I think about it. digi01 made a design a couple of years back.
http://www.diyaudio.com/forums/show...9816&highlight=
Digi's home page
http://assemblycraft.com/regulator.htm
4 boards + shipping for 22 USD, quite nice price. It's possibly 2 boards, I'm not sure.:confused: |
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| h_a |
@jackh: it seems I cannot reach you via email. Please mail me wether you are still interested.
@Agent.5: please mail me if you're still interested as well. My last board offers now Vout-caps (180uF low ESR) and additional pads for other TO-220 regulators (like lm338 and many others) as well (thank you for the suggestion, Sheldon!).
Thank you! All the best, Hannes |
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| agent.5 |
| quote: | Originally posted by h_a
@Agent.5: please mail me if you're still interested as well. My last board offers now Vout-caps (180uF low ESR) as well. |
Thanks for doing the group buy. Unfortunately, I will not be participating in it. |
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| h_a |
Ok!
Thanks for replying! All the best, Hannes |
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| h_a |
| what the postman brought today:D |
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| woody |
Was that $22 for 2 or 4 of those small boards? What were the
larger boards in the picture? |
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| h_a |
Hi woody,
the large boards are the regulator boards, 50x70mm, and came to 9E (about 13$) per board.
The small ones that you see in the picture are bridge-pcbs for the high voltage high current Schottky-diodes with ultra-low forward voltage - discussed here . With these little pcbs you can build a full bridge rectifier using 4 of these Schottky-diodes and I will offer a small number of them here.
If you're interested in the small Schottky-bridge pcbs, they're 25x25mm, drop me an email! :)
The regulator boards, however, are all gone.
Have fun, Hannes |
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| jackh |
Received boards from Hannes
Thanks
I also got diode info from this thread |
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