MBFM Transformer/PSU Questions

[NV]

I've been spending a great deal of time recently plotting out a build of the MBFM synthesizer and after progressing slowly but smoothly, I've run into something of a setback - the MBFM PSU. Before I start, I should preface my questions by saying that I've spent a fair amount of time dabbling with DIY projects, but the realm of power supplies has completely evaded me. I've never been in the position to have really dealt with them before, using wallwarts and kits and such instead. Hopefully I can overcome that now.

I've spent time combing through the two +/- 12v schematics on the Wiki (http://www.midibox.org/dokuwiki/bipolar_12v_psu?s=psu and http://www.midibox.org/dokuwiki/northernlightx?s=psu ) but I keep running into the same central issue, namely the transformer. Frankly, I'm just having trouble wrapping my head around the whole concept. NorthernLightX's wiki page lays things out in a pretty foolproof manner, but he utilizes a transformer that I cannot find anywhere outside of Reichelt, which brings up another issue - I'm located in the US (110/120V). Because of this (and please correct me if I am wrong) a 220/230V transformer would not work in my situation (not to mention importing from Reichelt would run me near $100 US). However, I cannot seem to find any 2x12V 50VA transformers anywhere in the US. I'm sure there is a very good reason for this, but like I mentioned PSUs are all a very new matter for me.

So to try and streamline my ramblings, here are my questions:

Would a US transformer (110/120V) work with the NorthernLightX schematic? Same components and layout, just a different transformer?

If so, is there a specific transformer that anyone recommends, or a direction that someone may be able to point me in?

By using NorthernLightX's PSU, I should have the needs of the MBFM and the additional AOUT module I am planning completely covered, correct? No need for an additional 9V/500mA wallwart as is mentioned in Thorsten's original plans?

I sincerely apologize if my questions seem redundant or if they have been answered in detail elsewhere, but I have honestly spent a great deal of time searching for these answers and have had no luck. I may be barking up the completely wrong tree in my research, but either way I am hoping that someone here may be generous enough to point me in the right direction. To all of you who may take the time to help me out, I truly appreciate it. This whole PSU issue has completely halted my progress and I cannot wait to work my way through it. Thank you!

[stryd_one]

Would a US transformer (110/120V) work with the NorthernLightX schematic? Same components and layout, just a different transformer?

Yes.

If so, is there a specific transformer that anyone recommends, or a direction that someone may be able to point me in?

We've all been grabbing some from pollin.de.

cheap transformer for bipolar PSUs at pollin.de But they'd need a slightly different schematic to NLX's. You already seem to be looing for the right thing, so you can probably ignore that.

By using NorthernLightX's PSU, I should have the needs of the MBFM and the additional AOUT module I am planning completely covered, correct? No need for an additional 9V/500mA wallwart as is mentioned in Thorsten's original plans?

Correct.

I have honestly spent a great deal of time searching for these answers

I can tell from your post! :) thank you! You're on the right track, so don't sweat it. You can go for a transformer that has a higher rating than 50VA, so if you find like 60VA that'll do fine, for example.... Sorry I'm down under but maybe another yank can help you find a good trafo?

[NV]

Thank you for your reply Stryd. I attempted to order a couple of those same transformers from Pollin a couple weeks ago, but the 230V input voltage had me concerned since I am at 110V in the US. They also charged me 30 Euros for shipping/handling which at that price gave me cause for hesitation, particularly when I am unsure if they will work here or not.

I've kept your suggestion of searching for ~60VA transformers in mind, but unfortunately I cannot seem to find any 2x12V transformers for sale with anything above 30VA. After that there is a rather large jump up to the 100VA range with no real middle ground, so it's either far underpowered or far overpowered. I've tried Mouser, DigiKey, Allied Electronics, and a handful of others with no luck. I have found individual companies which make the necessary transformer, but they only do large company orders and don't supply one-offs to distribution companies like Mouser or confused synth builders. Finding toroidal transformers in general seems to be particularly difficult as well, since of the few I've found in North America nearly all are "special order" parts with a premium price attached. I'm hoping that transformers aren't really supposed to be this hard to find and that I am just on the way wrong track here, but I just can't seem to find anything similar to NorthernLightX's recommended unit. Hopefully someone will burst out of the woodwork with godly news and renew my vigor.

I am operating on the assumption that using a 220/230V transformer in the 110V US will yield poor results. Is this accurate? I looked into stepup voltage units to raise the 110V wall voltage to 230V, but with the overseas transformer already running me about $80 US and the stepup unit costing around $30, I'm really starting to spend a great deal of cash on something which I imagine should be relatively inexpensive. I guess at this point I'm open to any suggestions anyone may have, so please feel free to fire away. In the meantime I'll keep the thread posted on anything I may find - perhaps others are experiencing the same issues.

[NV]

Alright, so after spending many fruitless hours combing every electronics and industrial distributor I could find in North America, both large corporations and small shops, I have come to the conclusion that a 2x12V ~50-60VA transformer, toroidal or not, simply does not exist in the US without paying an enormous premium for "custom work." So unless someone knows a secret that I am oblivious to, I think it may be best to direct my attention towards possible alternatives.

If at all possible I would still like to use NorthernLightX's PSU schematic, as my current approach to the internals of my chassis would fit perfectly with the small and organized footprint - something I highly doubt I would be able to accomplish by mashing together something of my own on vero board. However, at this point I am beginning to think that sticking with NorthernLightX's schematic simply will not be possible, unless someone has news I am missing (and please let me know if you do!).

Assuming that I did try to continue with NorthernLightX's schematic, is there a way I could achieve the same result using something like two separate 12V transformers? If so, how would I approach this? Would the power rating for the two separate transformers have to both be 50VA (which I also cannot seem to find...)? Or perhaps such an approach isn't even possible at all?

If anyone has anything even remotely helpful to say please don't be shy - at this point I could use any bit of help that you may be generous enough to offer. Thank you for your time and I hope someone can lend me a hand in working through this hindrance!

[seppoman]

you could use a 2x15V transformer, too. and 50VA is quite a lot, that's more than 2A on each rail. I'd say even with an additional AOUT, something in the range of 20VA is plenty - 20VA are 10 on each rail, 10VA with 12V are about 800mA. A MBFM should need less than 100mA bipolar supply, same applies for the AOUT.

You can't use a 230V primary transformer though, these would give you more than twice the rated output voltage.

S

[NV]

you could use a 2x15V transformer, too. and 50VA is quite a lot, that's more than 2A on each rail. I'd say even with an additional AOUT, something in the range of 20VA is plenty - 20VA are 10 on each rail, 10VA with 12V are about 800mA. A MBFM should need less than 100mA bipolar supply, same applies for the AOUT.

You can't use a 230V primary transformer though, these would give you more than twice the rated output voltage.

S

Thank you so much for your reply Seppoman. It's wonderful to hear from you, as I know the AOUT_NG was your creation and several of my power supply issues focus around integrating that module into my MBFM.

I've followed your advice in searching for 2x12V or 2x15V transformers with a lower VA rating and have found the following as the nearest possible result:

Pulse Low Profile Encapsulated Transformer 14 VA 2X12V@583mA

Data Sheet - http://www.pulseeng.com/products/datasheets/LT2006_29.pdf

I am unsure if this may be pushing the lower limits or not at 14VA, although it is rated for 583mA. Using NorthernLightX's schematic, would this transformer be enough for both an MBFM synth with complete control surface and an additonal AOUT_NG module? Or would something with a higher VA/mA rating be needed? I'm having a great amount of difficulty finding anything higher than 14VA, as beyond that point there is a minimum order of 12 or so units. I'll keep searching in the meantime just in case the 14VA will not be enough. Thank you both so much for your help! I truly appreciate it!

[NV]

Update: I've found a 115VAC transformer with the following specifications...

Type - Dual Primary

Primary Windings - Dual

Secondary Windings - Dual, No Center Tap

Series Output Voltage - 24 VAC @ 625mA

Parallel Output Voltage - 12 VAC @ 1.25A

Maximum Power - 30 VA

Data Sheet - http://www.pulseeng.com/products/datasheets/LT2006_32.pdf

Since this unit is above the 20VA you specified Seppoman, I assume this transformer would work sufficiently with NorthernLightX's schematic and adequately power an MBFM with control surface/LCD and an additional AOUT_NG module using one transformer/supply? Or am I wishing too hard? Thank you again for all of your trouble!

[stryd_one]

Sorry guys but remember - NLX's PSU does not only run the +/-12V power but also the 5V... You might want to select your LEDs and LCD before the transformer.

[seppoman]

yes, in the meantime I already noticed that issue - but instead of using a fat transformer I'd recommend using a second (7.5V or maybe 9V) transformer for the 5V rail. Nothing personal against NLX, but that construction only introduces troubles. It's loading the transformer very asymmetrically, plus there's a huge amount of heat to be dissipated from the 7809/7805. Best thing would, of course, be a single transformer like that Pollin one, but they're quite hard to find...

S

[stryd_one]

I agree.

[seppoman]

I forgot to answer about the two transformers you've found:

If you use a separate transformer for the 5V rail, the 14VA one is more than sufficient.

If you decide to go the NLX way, the 30VA should be ok as long as you don't use a lot of superbright LEDs (better anyway so you won't need sunglasses ;)). Usually LCDs are between 200 and 500 mA, the rest doesn't need much. So there'd be around 500 mA left for LEDs.

S

[NV]

Thank you both for your responses, I feel I am right on the cusp of figuring it all out and owe it to the two of you.

In response to Stryd, I have chosen my LEDs and my LCD. I am not intending on utilizing any superbright LEDs as they're a bit of a headache on a synth interface that requires alot of eye reference. I've chosen standard brightness LEDs with a forward current of 10mA each. From what I understand of the MBFM there should be no more than one LED on at a time in the selection matrix, as well as five others at a time in the Instrument/Operator column, so I anticipate a minor current draw from my use of LEDs (although I may of course be wrong). As of now my intention is to utilize a Hantronix 40x2 standard LCD for my display (Datasheet). After reading through the specs I anticipate much less of a current draw compared to other models, as I have heard murmurs that white edge-lit LCD displays (the model I am using) have a much smaller current draw than other colors by avoiding the back-lit arrays. The datasheet above rates the particular model I am eyeing as having a 50mA LED forward current, whereas similar models in yellow/green are rated around 230mA or even as high as 700mA. Regardless, I'm building my supply as if I were expecting a ~300-400mA current draw from the LCD to be on the safe side and employing resistors before the LEDs just in case. I do imagine that the more headroom the better, so if you feel that I may be heading towards a problem feel free to let me know.

Seppoman, given that I was intending on building two separate supplies at once (one for the MBFM + control surface + AOUT_NG, and one for a future MBSEQ + control surface + AOUT_NG + LED Matrix breakout), do you think it may be best to utilize an additional 9V transformer? I am under the impression that the 2x12V 30VA transformer I found will be sufficient for my intentions with the MBFM, but I am thinking that it may be cutting things a bit close (if at all) with my intentions regarding the sequencer. If I were to utilize an additional 9V transformer I imagine an additional power supply would also be necessary on top of NLXs, correct? Would a particular VA rating be recommended? Perhaps these questions may be best saved for a later date/thread, so feel free to let me know if you'd rather I keep this thread more focused.

Thank you both again for your help in guiding me through these matters. I feel I've made great progress over the past few days and I owe much of it to your helpful guidance, so thank you!

[seppoman]

do you think it may be best to utilize an additional 9V transformer? I am under the impression that the 2x12V 30VA transformer I found will be sufficient for my intentions with the MBFM, but I am thinking that it may be cutting things a bit close (if at all) with my intentions regarding the sequencer.

Well as I said, a second transformer will help avoiding heat anyway. But for a FM using that display, the 30VA transformer/NLX cirquit would be ok. You could omit the 7809 part because you don't need 9V. Instead of the high power resistor you could also use a 7809 like shown here (for MBSID): http://www.ucapps.de/mbhp/mbhp_core_power_fix.pdf. The resistor will work fine but become rather warm/hot, and it's easier to mount a 78xx to a heat sink than a resistor.

The FM would also benefit from a second transformer, but for a SEQ I'd really recommend using one (two displays, more LEDs, more of them staying on at the same time etc). 7.5V is even better than 9V, they're not that uncommon.

If I were to utilize an additional 9V transformer I imagine an additional power supply would also be necessary on top of NLXs, correct? Would a particular VA rating be recommended?

The PSU for this second transformer is already integrated on the core module, and for the bipolar supply you could go for the first schematic on the "bipolar 12 V" wiki page. So the two transformers method even makes the PSU more simple. A rating of e.g. 15VA would be sufficient for a SEQ (that equals 1.66A with 9V or 2A with a 7.5V transformer). For the FM, about 10VA are plenty.

S

[NV]

Alright...whew. So after analyzing the things you have both said and doing further research on my own into transformers and PSUs, I've decided that in the interest of preventing possible future problems and making my MBFM as efficient as possible I'm going to attempt to build a supply myself rather than utilize NorthernLightX's supply. My intention is to create two separate but identical supplies for both the MBFM and the SEQ. In order to do this, I will purchase a 7.5V transformer to power the 5V core, and then a 15V transformer and a schematic I have discovered from a few searches through the forum for the +/-12V AOUT_NG and OPL3. When I first discovered this supply I was a little overwhelmed by all of it and focused on NLX's instead, but now after learning quite a bit from you two and my own further research I think I am prepared to tackle it. At the very least it will be a growth experience.

The bipolar supply is linked as follows: http://www.generalguitargadgets.com/pdf/ggg_bipolar_ps.pdf (Hopefully they will forgive me for posting it extraneously...)

From what I have read this supply will more than adequately provide for my needs in both the MBFM and the SEQ, as well as being compact, efficient, and providing just what I need without unnecessary extras. Everything is quite clearly laid out in the documents, so if anyone would be so kind as to entertain just a few more questions to make sure I am on the right track then I would once more be in your debt:

When powering the core module, I am under the impression that providing more than the recommended 500mA in order to provide some headroom does not present any problems with the circuit (such as providing 1A with a 7.5V transformer). Is this correct?

I am under the impression that the MBFM and AOUT_NG require less than 100mA each to function properly (as seen here: http://www.ucapps.de/mbhp/mbhp_opl3_psu.pdf). Given that this is the case, I am assuming that a 15V transformer supplying more than 200mA should be fine with the above linked single-transformer schematic to power both modules. Since the supply is turning a 15V transformer input into a bipolar 12V output, will this affect the mA rating of the transformer at all? Is there a VA/mA range that may be recommended?

When utilizing two separate transformers (in my case a 7.5V and 15V), how do you wire them up to a single AC line?

Thank you both so much for all of your assistance. At this point I am beginning to feel quite comfortable with the entire subject, although I am well aware I still have much to learn. Regardless, it is fantastic having a resource such as this with patient and knowledgeable people willing to provide assistance to newcomers. Thank you!

[stryd_one]

7.5V transformer to power the 5V core

I'd go for 9V, just to be sure.

a schematic I have discovered from a few searches through the forum

We love when people do their own research, it makes it so easy to help :) There's a similar schematic on the wiki here, and someone tried it unsuccessfully recently. Don't let that put you off, but I should mention it. It was never determined why it didn't work.

When powering the core module, I am under the impression that providing more than the recommended 500mA in order to provide some headroom does not present any problems with the circuit (such as providing 1A with a 7.5V transformer). Is this correct?

Correct. That is a maximum rating, it will only put out what the core draws in, so that's just extra headroom.

I am assuming that a 15V transformer supplying more than 200mA should be fine with the above linked single-transformer schematic to power both modules. Since the supply is turning a 15V transformer input into a bipolar 12V output, will this affect the mA rating of the transformer at all? Is there a VA/mA range that may be recommended?

I dunno... that's a 24V swing, so I think you'll get a lower maximum amperage per pole, but I think bipolar ratings are done for the full swing from pole to pole anyway.

When utilizing two separate transformers (in my case a 7.5V and 15V), how do you wire them up to a single AC line?

In Parallel, but beware of ground loops.

Seppo will probably come and fill in the blanks in my post soon :)

[Shum]

Hi NV,

You probably be able to get the 12v ct 3A transformer from RadioShack.com. The model # 273-1511 or catalog# 237-1511. The primary is rated at 110v that is what you are looking for. I have used transformer of the same rating for my midibox64 and other projects that require regulated voltages of +/-12 and 5v. Hope this information will help.

Regards

Shum

[seppoman]

From what I have read this supply will more than adequately provide for my needs in both the MBFM and the SEQ, as well as being compact, efficient, and providing just what I need without unnecessary extras.

as stryd already pointed out, this is quite the same as the second one on the bipolar wiki page. I guess it would work but would give more ripple on the supply voltage. so there's no real reason not to use the 14VA transformer you found in the first place (or the 15V version from the same series) :)

When powering the core module, I am under the impression that providing more than the recommended 500mA in order to provide some headroom does not present any problems with the circuit (such as providing 1A with a 7.5V transformer). Is this correct?

correct. and maybe 9V is better after all. I used a 7.5V transformer before without problems but the margin is maybe a bit slim considering the voltage drop over the rectifier. I'd go for an at least 1 A, better 1.5 A transformer, especially for the Seq.

I am under the impression that the MBFM and AOUT_NG require less than 100mA each to function properly

That's right. Depending on what you want to control with the aout_ng and if you want to power that stuff from the same PSU, you could either use the 14VA transformer or go for a slightly higher rating.

When utilizing two separate transformers (in my case a 7.5V and 15V), how do you wire them up to a single AC line?

Nothing complicated about that. just connect them in parallel. On the secondary side, if you use that dual transformer, you need to take care that you connect the end of one coil to the beginning of the other. Don't make the "ground" connection at the same side of the coils or you'll get the transformer humming and getting hot. but if it's wired the wrong way, you'll notice that effect very fast :)

S

[NV]

Thank you all for your enormously helpful replies! To begin, thank you Shum for your transformer recommendation. I will certainly keep it in mind for future projects, although at this stage with my MBFM I have chosen to utilize a different transformer set. Regardless, I think it will prove very helpful to others who choose to utilize NLX's schematic for their projects and I will look forward to finding my own uses for it as well. Thank you for your help!

To Stryd, thank you for your advice. I will certainly keep the possible power supply complications you have mentioned in mind. Should the schematic I am utilizing prove to be troublesome I will do my best to figure out where the problem lies for future builders. As for the 24V swing, I am intending on utilizing a transformer which will provide solid headroom amperage with that possibility in mind, so hopefully it shouldn't become an issue.

To Seppoman, thank you for your recommendations. It's been very helpful to be provided with your suggestions so as to give me a general idea of what to be shooting for. Using the advice you have both given me, I have found the following two transformers:

For Core Module:

Type - Standard, 115V 50/60Hz

Windings - Single primary/single secondary, no center tap

Series Output Voltage - 9VAC @ 1.77A

Parallel Output Voltage - N/A

Maximum Power - 16VA

Data Sheet

For Bipolar Supply:

Type - Standard, 115/230V 50/60Hz

Windings - Dual primary/dual secondary, no center tap

Series Output Voltage - 16VAC @ 1.25A

Parallel Output Voltage - 8VAC @ 2.5A

Maximum Power - 20VA

Data Sheet

I'm operating under the assumption that the combination of these two transformers and the bipolar schematic I provided earlier would provide adequately for the MBFM synthesizer and the SEQ, both with additional power requirements (AOUT_NG module for both, LED matrix breakout box for SEQ). Of course, if I am wrong feel free to let me know. Would 1.25A be a bit much for the bipolar supply? Would it be possible to go for something like 700mA, or would it be best to stick with something closer to 1.25A in case there is an issue with the stepdown from 16V to +/-12V affecting the amperage? From what I have learned, I feel quite confident in these two choices and am excited to finally move away from the power supply stage and back into the work of preparing and ultimately assembling my FM synthesizer, as well as plotting out the rest of my SEQ. Thank you all so much for your help, you have made this entire process so much more inspiring and informative!

[Shum]

Hi NV,

In my opinion, I would go for a Bridge configuration Bipolar power supply (with 2 secondry windings) as it has a lower ripple value of 48% (good for audio application) compared to a half wave configuration (with 1 secondary winding) that has a ripple value of 120%. Figure 1 in the attached schematic is a typical Bipolar power supply. Also I would suggest you use the transformer model # 14A-30-36 with a rating of 20VA from the data sheet you provided.

Regards

Shum

1bpsu.JPG

[NV]

Hi Shum,

Thank you for your recommendation. Fortunately I have been able to find a significant stock of the transformer you mentioned, so that makes things much easier. Your schematic is especially appreciated since I can integrate it into the existing schematic I was planning with different capacitor values and minor layout changes to accomodate the parallel transformer and bridge rectifier. Is there a specific value you recommend for the bridge rectifier?

While I have spent some time looking into voltage ripple and understand what it is, I am having trouble discerning what the effect would be on circuits such as those in the MBFM. I imagine reducing the voltage ripple would simply reduce noise and extend the longevity of the circuits, although I am unsure if this is entirely correct or if there is much more to it.

Also, the transformer you suggested has a parallel output of 18VAC @ 1.64A. Using the schematic you provided, would it be possible or even advisable to use a transformer with a lower parallel amperage (such as 18VAC @ 1.1A or 700mA)? I am attempting to keep the total amperage of my MBFM and SEQ under 3A, although I can certainly go above that if it would lead to better overall performance. Given that the OPL3 and AOUT_NG boards have such a small amp draw of ~100mA each, do you think a lower amp output on the transformer would present any issues? Or does the swing from 18V to +/-12V affect the amperage enough for it to be a concern? Thank you for your advice!

[seppoman]

Hey NV,

you really are starting to make things more complicated than they are - I think all you need to know has been said before now ;)

Except: Ratings of bridge rectifiers are just the maximum allowable values, i.e. a B40C800 would take 40V and 800mA max, so as the prices don't differ much als long as you're not going for a HUGE PSU, just use e.g. a B80C1500 or somthing like that.

The basic principle of Shum's schematic in fact is the same as the first one from the Wiki except the missing secondary 100nF caps (which you should install, too). The cap values of Shum's schematic are quite sensible, so just take them and add these secondary 100nFs.

About the transformer: 2x14V or 2x15V is definitely enough, if you're going higher you only generate more heat by that. Use e.g. the 14A-20-28 or the 14A-30-28 from that PDF, or from the Pulse/ERA PDF from last week, the 039-5311.0 (30VA). As long as you're not hooking up a modular synth to that same PSU, even the 039-5104.0(14VA) would suffice. Just choose one of them now and get going  ;D

ripple: yes, ripple means noise, so it's something you want to keep reasonably low :)

S

[Shum]

Hi NV,

Seppoman is right, enough has been said already and you should get on with the project. In my opinion using a transformer with a higher rating then needed is fine unless the cost differential is not substantial. For your applications, those transformers which have been selected are fine. I have attached a working schematic showing the two PSUs for the Core and the Fm modules.

The lower amp output of the transformer is not an  issue provided the loading is within this output range. Each 18V winding with a rating of 820mA, provides a stable regulated DC output of +12V and -12V. The maximum current which can be drawn from the +/-12V is 820mA ( 820mA x 2 x 18 = 30 VA) each. If you draw more current than this you will overload the transformer and it will get hot.

Regards

Shum

psu2.JPG

[NV]

Thank you very much for your input Seppoman and Shum. I apologize if I stepped on anyone's toes here, my intention was just to make sure everything would work together before making any investments. As I mentioned earlier I have a solid amount of experience with DIY projects in general, but the concept of building bipolar power supplies is a new topic for me and one which I figured warranted more of a sense of perfection when dealing with potentially dangerous voltages. Shum's admirably detailed schematic has provided me with exactly the information I need to complete the puzzle.

My original intent in this thread was to find accessible distributors for MBFM/SEQ capable transformers in North America, which after some scouring I have been able to locate. Once I've established more of a sense of what is actually in stock as opposed to carrying large hidden minimum orders I will post a list to assist those who may be struggling with similar issues. Judging from the many bipolar PSU postings in the MBFM forum, I feel this topic is often the primary roadblock for potential builders. As such I hope that much of the information in this thread will prove fruitful to others in bypassing that point.

I hope my many questions did not prove too aggravating. I do feel quite comfortable with the topic at this point which is considerably further along than I was a week ago, so your efforts in assisting me were most certainly not in vain. Once I have nailed everything down definitively I will try to make something which may help others in a similar situation as I have found myself. Thank you all again for your considerable time and trouble and know that it is enormously appreciated!

[stryd_one]

I guess I can see both sides of the fence here... because there's no real tried-and-tested way to do the bipolar PSU, it's a bit sketchy to get stuck into it, and if you're new, you don't really know when you have all the info... I mean... How do you know you haven't missed something, if you don't know anything about what you may or may not have missed?* It's an unnerving feeling. But the guys are right, you'll be set to go with what you've got, and a bit of luck :)

And, if you want to earn some serious brownie points, document it for us with pics and text and schems and test results and such, so that future NV-alike people will have no fear :)

*Can anyone remember the GW Bushism that sounded like that?

[faton]

I read some messages before (about NLX PSU):

It's loading the transformer very asymmetrically

What is asymmetrical? Is it because we have more charge on +12/+9+5 than on -12?

Do you think it can become a problem, on a long time? I have done the NLX PSU and I have a good result,

I am not an electronic expert, but I was agree with that schematic... It seems to be correct.