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frailn

MBFM Bipolar Power Supply Kit

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After reading and rereading and rerereading this post regarding bipolar PSU for the MBFM, I did some looking around on the internet and found a bipolar psu kit from PAiA that delivers +/- 12VDC @ 300mA. It seems like this kit should work for the MBFM, but I'm unsure about the "300mA." The kit is $41. This might be a good find for FM builders in the US, if 300mA is enough for the FM. Can any FM builders confirm that this PSU kit is good for the FM?

Link to the site:

http://www.paia.com/proddetail.asp?prod=9770R-12

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That page has a lot of good information! However, purchasing their PCB, plus shipping, then buying the parts from Mouser, Digikey, etc...plus shipping would seem to be more expensive. I like the PAiA kit because it includes everything you need, including the wall wart for $41. Shipping within the US shouldn't be bad.

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Okay, I answered my own question ::) - The PAiA PSU does not have enough mA to run a good FM box with LED's and Backlit LED. Off to read more on the PSU PCB at Music from Outerspace.

EDIT: I'm wrong on this - see below

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btw for giggles I just put all those parts to fully stuff that MFOS PS into the mouser cart. Including the wall wart came to approx 30 shipped. Its not so bad

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Okay, so I just found this schematic, which tells me that the PAiA kit works. I was wrong! I should do more reading and less posting! BTW, that's not too bad for the mouser parts. I think I'm going for PAiA kit, and just get it all in one bag. It comes out just a little cheaper than MFOS board + Mouser order, not much, though. So others could go either way. Thanks for looking that up on Mouser, lief!

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300mA should be plenty to supply the OPL3 board alone; the OPL3 really only needs less than 100mA on average, as you've seen from Thorsten's schematic. The rest of the MBFM is powered by the 5V supply in the CORE board, so as long as you're supplying enough power for the 5V then the bipolar PAiA supply should integrate well enough for most everyone's uses. The only reason you may need more is if you chose to utilize an additional bipolar AOUT, but even then the extra 200mA should very well prove sufficient to drive it.

One concern would be that the kit utilizes a wallwart transformer, which is only really an issue if you want to keep things a bit neater from the outside and avoid having two separate plugs for the MBFM. However I imagine that most people utilizing this kit won't be interested in AOUT options, fiddling with transformers, or concerned about additional plugs, so for those purposes it should certainly get the job done in one clean shot.

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Hey $15 bucks for a ready-to-go +/-12V regulated PSU, that's awesome!

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:D Perfect! Thanks for the link!

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heya fräulein, did you ever get around to buying one of those Condor PSU's?  i've got a MBFM waiting for a psu...  just curious if it worked out or not. ;)

(anyone can answer, not just fräulein.)

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I did buy one of those PSU's. But, I have not started on the MBFM, yet. It's collecting dust along with the two old sound cards I purchased on eBay that have the relevant MBFM chips. I'm going to tackle the MB6582 and Lemonhorse's AY-3-8912 before I work on the MBFM....saving the hardest one for last.

If you have any questions about the PSU, I can dig it out and try to answer them or even take photos and post them here.

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I did buy one of those PSU's. But, I have not started on the MBFM, yet. It's collecting dust along with the two old sound cards I purchased on eBay that have the relevant MBFM chips. I'm going to tackle the MB6582 and Lemonhorse's AY-3-8912 before I work on the MBFM....saving the hardest one for last.

If you have any questions about the PSU, I can dig it out and try to answer them or even take photos and post them here.

no need for pics. ;D  i just wanted to know if you had actually purchase one, you know, to see if they were reliable/worth the effort.  thanks for the reply! :D

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To move from the bipolar power supply itself to the transformer (I made a bipolar from a 7812 and 7912 pretty much lifted from the PDF datasheets, but with more input capacitance)....

When I made valve amps in the past, the transformers always put most projects out of range.

I've hand wound 3 High Voltage and Heater toroid valve mains transformers which have run without hitch for years. This means removing all the secondary windings then adding your own. For these kind of voltages, you're talking about hundreds, if not closer to a thousand+ coils ;) It's worth it! They make great PSUs.

I've actually wound a toroid especially for the MBFM already, here's a poor picture:

FM01.JPG

I modified the 5.8v~ winding up to 9+v~ for the 5v, but the other winding is fine.

Should be enough for the low current draw. Already tested the +/- 12v  circuit. Oh. You may notice I have no centre taps on the secondaries? No problem. There is a voltage doubler in the +/- 12v circuit, so 12.8v~ is fine and actually produces roughly +/- 18v DC.

I haven't managed to rewind a laminated transformer yet without problems, so I don't recommend doing this with the ordinary laminated transformers, just toroids.

To do this, you need to make a long shuttle, about 8-12" long, narrow enough to fit through the centre of the toroid. Like the shuttles in weaving. I used thin mdf and pine. Wind on an overestimate of the wire to this first and wind away. Coated copper wire of course.

If you choose a toroid with a suitable winding on it already, you'll need less additional windings  ::)

Generally, I've found toroids with higher voltage secondaries need less windings per volt. (easier on you)

To measure the windings per volt, wind on 10 turns and measure the AC volts.

This also tells you the rough primary windings..

Make sure your wire is rated above the approximate current draw of the circuit it is to power and double that to be safe. Within reason.

It may sound like a real PITA, but it only takes about an hour or two to do once you've done one and they work a treat.

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Did any one purchase a few of those $15 12v PS from here?

http://www.skycraftsurplus.com/index.asp?PageAction=VIEWPROD&ProdID=439

Out of stock.

It looks like they've got almost the same thing (same specs, different manufacturer, doesn't have remote sensing terminals) for US$0.05 cheaper with screw terminal outputs:

http://www.skycraftsurplus.com/index.asp?PageAction=VIEWPROD&ProdID=1100

Datasheet at:

http://www.solaheviduty.com/products/powersupplies/pdfs/manuals/sl/sld12-1010-12tmanual.pdf

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Noisy as in noisy audio signal or a noisy power brick?

The power supply will be noisy, leading to some noise on the audio signal.  How much noise depends on the power supply filters, ripple rejection of the opamps, switching frequency (52kHz in this case), etc, etc.

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