PCB layout for (not only) SL-PSU

fonik · Last edited by fonik on Mon Aug 21, 2006 6:57 am; edited 1 time in total

hi all,

i designed a PCB layout of a small PSU for my soundlab.
it converts 9V AC to +12/-12V DC and +9/-9V DC (approx. 100mA). actually its a counterfeit of the doepfer a100 miniNT.
using a wallwart transformer (9V AC, 500mA) you don't have to care about high voltages!

http://modular.fonik.de/soundlab/sl_psu.pdf

the layout is a positive for press'n'peel blue...

matthias

Coriolis · Joined: Apr 11, 2005 Posts: 616 Location: Stilling, Denmark

That looks nice! Do you have a schem you can post of that?

C

fonik · Posted: Mon Aug 21, 2006 4:48 am Post subject:

here we go:

SL PSU.gif

Description:

C1-C4 electrolytics 2200uF, C5-C12 ceramics 100n, D1-D4 1N4001

Filesize:

8.96 KB

Viewed:

318 Time(s)

This image has been reduced to fit the page. Click on it to enlarge.

Coriolis · Joined: Apr 11, 2005 Posts: 616 Location: Stilling, Denmark

Kewl, thanks!

C

a.b.o.z. · Posted: Wed Apr 18, 2007 1:32 am Post subject:

where to find wallwart 9v AC.
i got a buch of 9V DC for stompboxes. could i use two of those to get 9V +/- like with batteries..

Uncle Krunkus · Posted: Wed Apr 18, 2007 5:41 am Post subject:

As long as neither of them are earthed, it would be okay, but not good practice. Use it until you can get a proper +/-PSU happening.
The reasons are a bit involved, but the fact that they need to be not earthed is a worry to start with. If you want a more detailed explanation I'm sure we can get one together ASAP.

a.b.o.z. · Posted: Wed Apr 18, 2007 6:06 am Post subject:

yes not grounded. buch off boss and korg wall warts are not grounded.. i'm right, right?
thats cool than..until i get propper psu.
doepfer had something like that in their shop. psu using two wall warts..

Uncle Krunkus · Posted: Wed Apr 18, 2007 6:13 am Post subject:

My Boss one is grounded. But I s'pose it's more than likely a different one to yours. Does it have just two pins plugging into the mains? Or is there a third one? If it has a third one, check with a multimeter that there is no connection from the third one to either of the output wires. Then you should be right to go.

Lemmy · Posted: Wed Apr 18, 2007 6:25 am Post subject:

Hi,
When using this scheme, does it matter if the 9VAC power supply is unregulated?

a.b.o.z. · Posted: Wed Apr 18, 2007 6:57 am Post subject:

no third connection to mains. just two.

Wild Zebra · Posted: Wed Apr 18, 2007 7:17 am Post subject:

Nice Fonik!

Uncle Krunkus · Posted: Wed Apr 18, 2007 7:54 am Post subject:

AC is never regulated.
Well, not in this sense of the word.

AC is what you get straight off the secondary of a transformer.
Put that through a rectifier and you get a very spikey DC.
Put that across some big caps and the spikes become a ripple.(50Hz hum)
Put this into a regulator and you get regulated DC.

BTW The last 3 are what this circuit does. Smile

a.b.o.z. · Posted: Thu Apr 19, 2007 3:01 am Post subject:

Uncle Krunkus · Posted: Thu Apr 19, 2007 4:32 am Post subject:

Yes, could someone with a bit more theoretical background please explain this? I have some vague notions about chassis earth and electrical earth conflicting, or the potential for conflicts (pun intended Very Happy

), but I get the feeling there's more to it than that.

Lemmy · Posted: Thu Apr 19, 2007 4:38 am Post subject:

Cheers Uncle K, i have a lot to learn Smile

Fonik, (or anyone else) I'm having problems finding an LM7809 and an LM7909 here in the UK. Do you know a supplier or can you suggest alternative components?

I notice you mention heatsinks on the pdf file - should they go on the LMxxxx parts? Something like this? LINK

I'm also a bit stuck finding 50K pots for the fine tuner mod. Crying or Very sad

Uncle Krunkus · Posted: Thu Apr 19, 2007 5:11 am Post subject:

The 7808/09 are so standard that you'll find them just about anywhere that sells wire. Very Happy

Where do you get your other components from?
Any TO220 type heatsink should be fine, but like Fonik said, get some of the bigger ones. (BTW heatsinks are usually listed with their thermal resistance value, so learn how to read that. The smaller the value, the better the heatsink, and usually the bigger it's size)

Lemmy · Posted: Thu Apr 19, 2007 5:33 am Post subject:

I've been using Rapid Electronics. Also tried Maplin and RS Components. And E-Bay. Found something on Farnell, but you need to order at least £20 worth of stuff to use a credit card there...

Uncle Krunkus · Posted: Thu Apr 19, 2007 6:40 am Post subject:

I just checked Rapid Electronics and I can't find them either! Shocked

I checked all over their 1A fixed regulators page, and there are none.
That isn't just weird, it's seriously fucked up.
I'm not sure what to think.
Are 9V regulators prohibited in the UK or something? Rolling Eyes

Hey Tom! (v-un-v) What's going on? Have I slipped into an episode of The Twilight Zone?

Uncle Krunkus · Posted: Thu Apr 19, 2007 6:47 am Post subject:

I just checked Maplin.
None there either.
I'm going to bed before my brain starts dribbling out of my ear! Laughing

Lemmy · Posted: Thu Apr 19, 2007 9:51 am Post subject:

Thanks for looking... So it's not just me then. Shocked

EdisonRex · Posted: Fri Apr 20, 2007 8:09 am Post subject:

Check RS Components in the UK. http://www.rswww.com and look in their considerable s/transformer/power regulator/ selection.

I found 9V linear regulators there.

Lemmy · Posted: Fri Apr 20, 2007 1:36 pm Post subject:

Hi Edison,
If you could post a link that would be great. I'm struggling to find these. Can you suggest alternative components to the ones I mentioned?

EdisonRex · Posted: Sat Apr 21, 2007 2:23 am Post subject:

EdisonRex · Posted: Sat Apr 21, 2007 2:36 am Post subject:

And for those looking for 9V AC transformers, I noticed that RS Components lists some 9V toroidal 1.6VA transformers for £8.79 apiece, those aren't wall warts, though.

There are, however, 2 listed 9Vac 9VA external wall adaptors listed. Part numbers are 400-6901 and 400-7049.

Again, hope this helps.

Lemmy · Posted: Sat Apr 21, 2007 3:46 am Post subject:

Nice one, many thanks.
I found the trick to using their search facility too: change the search type to "Manufact. part number" instead of "keyword". Then you get a useful result for e.g. a "7809" search.