Custom Power Supply for mb6582

[Shuriken]

I am curious what you have come up with. So looking forward to seeing your schem.

[technobreath]

Hi

As it turned out i had too little time to work on the schem this saturday, so i will do some work tonight and monday evening. I recon i will have a schem ready then for you to see.

I have thought of a couple of new things to add, ie led indicators for normal op and protection.

Ill see if theres a simple way to do it. Afterwards i would need some serious evaluation of the schem from people who knows this stuff, so if anyone feel like they can verify the design and suggest changes, speak up.

[Shuriken]

Hi

As it turned out i had too little time to work on the schem this saturday, so i will do some work tonight and monday evening. I recon i will have a schem ready then for you to see.

I have thought of a couple of new things to add, ie led indicators for normal op and protection.

Ill see if theres a simple way to do it. Afterwards i would need some serious evaluation of the schem from people who knows this stuff, so if anyone feel like they can verify the design and suggest changes, speak up.

Ok, well i am working on my schem atm. Now wondering if instead of just using a 78S05 it would be a good idea to combine it with a transistor something like a tip2955. That way it would have a little more room to breath. And better power dispensation. Also struggling to add the MC3423 to my eagle library. :pinch:

[technobreath]

This is a good idea, and is very similar to my design. But current limiting / crowbar and fuse is even more important with pass transistor.

I have looked at tip31c as the limit transistor. Its 10A. Havent done the math yet, so ill have to do some calcus to see what the actual needs are.

[Shuriken]

This is a good idea, and is very similar to my design. But current limiting / crowbar and fuse is even more important with pass transistor.

I have looked at tip31c as the limit transistor. Its 10A. Havent done the math yet, so ill have to do some calcus to see what the actual needs are.

This is what i have come up with so far:

This design should be sufficient for 5A on 5V+ line.

The TIP2955 is 15A. And the packaging is a bit bigger then the TIP31. I haven't really specced the thyristor yet, just picked one from Eagle lib.

Edit: Meh, i need to add a short circuit protection as well.

Edited February 13, 2011 by Shuriken

[technobreath]

Hi.

It might be that the pic is lowres or i cant see it properly on my shitty htc, but i cant seem to understand the meaning of the transistor that passes over the vreg. I mean, i see its the pass transistor, but how does it actually work? I thought its base was supposed to connect after the vreg and not before... again i am no expert though... hehe. Ur schem seems interesting though, a bit more advanced than my basic idea... could u explain what the intention with the design is? Good work. It would be cool if we could come up with a fairly simple but good design that everyone can use. When i started projecting the psu i soon discovered that it was far more to designing a good psu suited for this delicate application than i first thought. I really enjoy learning about it. I have struggled for many years to learn about psu, logics and electronics in general and really understand it. I never went to any school about this, so everything i know i learnt from the internet, my dad who used to design industrial robots for a living and from the good people in here. Especially smash and nils.

Im working on the schem tonight, and ill post it later on.

[technobreath]

Sorry, cant find a way to edit post on my phone,

But another thing i thought about is that i have some huge mosfets lying in box here. They were intended for driving big dc motors on a precut saw. The technician on the site left them behind in the factory they built it along with other components. They are rated about 100amp if i remember correctly.

It would be cool to use them instead of the bipolars. A wee bit overkill yes. But since i have them... i havent studied mosfets very much, so if anyone has an idea on if mosfets can be used please speak up...

I will anyway make the design for bipolars, but i could use them in my supply and make the necesary changes for my own psu if they can be used.

[m00dawg]

Actually I think it would make more sense to put a current limiting transistor before the regulator? If you are using multiple regulators off of one transformer, for instance, you can have just one master current limiting circuit for the whole works?

[Shuriken]

Please have a look at the 78xx datasheet at page 24 figure 13.

As you can see there, the application of the transistor is not current limiting. If the current surpasses 1A the transistor will take over. This will increase the current output to a max of 3 to 5A depending on the transistor used. As i said the design is not short circuit protected. So i should adapt it to resemble figure 15. at page 24 of datasheet.

My intention is to use 2 transformers. 1 for 5V and 1 for 9/12V line. The 5volt line is most sensitive. Hence the more intricate SCR design. I intend to include a simpler (less sensitive) zener diode based scr design on the 9V/12V line.

Edited February 13, 2011 by Shuriken

[m00dawg]

Ah ok...yeah I dunno if you need 3-5Amps for our purposes :) Many regulators can go 1-2A with proper heatsinking and that's likely more than you would need in most of the applications. Can't hurt though, I suppose.

[strophlex]

Those are rated 15VA, it's been years since I was into this stuff but please correct me if wrong; that means 2A for the 7,5V trans and a little more than 1A for the 12V one, right?

Yes, 2A for 7,5V but just 0,625A for the 12V rails. The same transformer is used for both + and - 12V.

@technobreath:

I didn't write the wiki entry, just used the design. I added some diodes to the output part to protect against reverse voltages.

@m00dawg:

I will provide some pictures. THe base board is not fitted in the box. The synth is in a P-10 enclosure. The 1U box contains PSU and expansion stuff. It is very crowded...

Edited February 14, 2011 by strophlex

[Futureman]

http://cgi.ebay.com.au/MEAN-WELL-30W-Triple-Output-Switching-Power-Supply-/300525846546?pt=LH_DefaultDomain_2&hash=item45f8bc8012

Thats what I used.

http://shop.ebay.com.au/i.html?_nkw=mean+well+triple&_sacat=0&LH_AvailTo=15&_odkw=power+supply+triple&_osacat=0&_trksid=p3286.c0.m270.l1313

I A-B'd it with a C64 power supply and could not hear any difference... even at excessive gains.

Modern SM power supplies switch at way higher frequencies than the older type..

Regards

Mike

[NorthernLightX]

I have been thinking about a switcher as well, but am hestitant because I also want to use AOUT and SSM boards. Toroid trafo's still are the way to go in audioland AFAIK...

[findbuddha]

http://cgi.ebay.com....=item45f8bc8012

Thats what I used.

http://shop.ebay.com...6.c0.m270.l1313

I A-B'd it with a C64 power supply and could not hear any difference... even at excessive gains.

Modern SM power supplies switch at way higher frequencies than the older type..

Regards

Mike

The Meanwell SMPS are very popular for powering DIY audio amplifiers.

[m00dawg]

I doubt this tired old debate of "to switchmode or not to switchmode" will ever cease, but every-time it comes up, I learn something.

I will say I am running a switching DC power supply on my sammichSID at the moment since I just haven't run into an extra AC power brick nor have I gone out and grabbed one up from Goodwill. It sounds great - I've even used it for recording, though that was because I forgot I was using a switching supply. If I had remembered, I would have swapped it out before that.

I would imagine that using certain filtering caps can mitigate the noise, if not totally eliminate it. Maybe this is a place where tantalum (another fun debate) might be useful since I recall it handles HF noise fairly well. I wonder if the HF noise from these guys can be picked up on an oscope?

I myself prefer a linear supply because they are fun to build; but I'll admit, having something that is "good enough" if not perfect would be good initially, particularly if it has some of the built in protection we have been discussing here. That way I can go about working on the other parts of my synthesizer.

But back to the world of linear, I just found this from Allied Electronics in my inbox. First e-mail from them that might actually prove to be useful:

I haven't looked at the spec sheet yet but perhaps this might be something to look at.

Edited February 15, 2011 by m00dawg

[Futureman]

The Meanwell SMPS are very popular for powering DIY audio amplifiers.

Modern SM power supplies also have a much higher switching frequency than in the past.. waaaay above the audio spectrum.. Plenty of people are using em for racking up vintage channel strips from old consoles etc, including some serious racking specialists that I know. I figured, that if it's it good enough for them, it'll be good enough for a noisy as F@#k SID synth.

Cheers

Mike

[m00dawg]

Something definitely worth looking into. I'd save some space for my MB-SID rack. That said, I still like linear supplies just 'cause I guess. As far as SIDs being noisy, that's sort of true (they aren't THAT noisy). I find that any noise you do get from the SID is part of the character of it. I don't want to introduce noise that isn't there for sure.

I'm waiting for the linear PSU peeps to voice their opinion but, yeah, it sounds like a good solution, particularly if it has built-in protection (that's a biggie because, if not, I can just as easily make a linear PSU).

EDIT: Looks like it has current limiting protection according to the Spec Sheet. This could be a contender!

Edited February 15, 2011 by m00dawg

[m00dawg]

Here's a few places I found a similar model:

Mouser - $46.00

TRC Electronics - $34.29

Edited February 16, 2011 by m00dawg

[Futureman]

. As far as SIDs being noisy, that's sort of true (they aren't THAT noisy).

Well, they are easily the noisiest bit of kit I own... yep, not offensive.. a nice soothing 8 bit noise, but you sure can hear it when it's switched on and nothing else is playing.

Also, regarding the price, when I check the mouser link it shows me $62.. not $46, unless you get different price breaks in the US etc.

I find Mouser is rather expensive her in Australia, sure, convenient and a vast catalogue, but expensive.

regards

Mike

Edited February 16, 2011 by Futureman

[m00dawg]

Yeah it's definitely $46 here (checked again just to be sure). Usually I use Allied Electronics as they are the next city over and so shipping is (usually) super fast. Didn't find these PSUs there though, and, speaking of expensive, they tend to be :) There's DigiKey as an alternative - perhaps they might have a few.

For cost savings, the only thing I can think of is trying to see if people want to rock a bulk order. I was thinking of offering that for my LED matrix board I'm working on; but I don't think I'm quite ready to manage one of those things yet :) Otherwise, the prices on eBay seemed pretty reasonable so that might be an avenue as well?

EDIT: One thing I did notice, though - there's no 9VDC so that will have to be regulated. I wonder, do the protection features of the PSU make having to make a simple 9VDC power supply (or using the MB6582 mainboard perhaps) negate some of the benefits of the switchmode supply?

Edited February 16, 2011 by m00dawg

[Futureman]

Regarding the 9vDC.. yea, I suppose you could use the 12v and regulate it down.. You probably don't need any other components apart from a regulator.

I had height & room constraints for the inside of my 6582 synth, so the SM PS was a nice tidy solution. It also runs very very cool, which was important, considering the SID's get warm enough on their own.

Cheers

Mike

[janvanvolt]

I got a Meanwell T 60B now (+/- 12V, 5V), so what do i need additionally to use it with the MB6582 ?

[m00dawg]

If you are using 8580 or 6582A SIDs, you need to supply them with 9V so either have to figure out how to use the regulation found on the MB-6582 or build your own. I haven't looked at that part of the MB-6582 schematic in a while to know how easy that would be. Wilba made the PSU options fairly configurable though this particular setup is not one of the documented PSU options.

I would like to keep heat away from the MB-6582 baseboard so if I go with this PSU option, I will likely just use a simple circuit off the PSU to supply 9VDC. Since the 12VDC supply is already a stable output, I don't need to do most of the tricks talked about in this thread (though may want the regulator protection diode. You can check out some of the spec sheets that have been passed around in this thread for what that looks like. If you go this route, you can also look at the spec sheet of the regulator you buy just to match capacitance values and such.

Even when having to regulate 9V on your own, it will still end up being quite a bit less heat than going with a linear option (at least when using one transformer) - plus you get a supply that has a good amount of built in protection. Anyways hope that helps!

[strophlex]

I feed 12V DC into my MB6582 where it's supposed to have 9V AC. The voltage goes through the rectifying bridge (loose some voltage) smoothing caps (no change) and finally through regulator (regulated down to 9V). It works fine and doesn't seem to generate much neat (actually I think it generates less heat than the standard 9V AC way). One thing I am thinking about though is if the dc cable is more prone to pick up noise than an ac ditto.

Edit: Changed a misplaced DC to AC.

Edited March 14, 2012 by strophlex

[nebula]

I feed 12V dc into my MB6582 where it's supposed to have 9V dc. The voltage goes through the rectifying bridge (loose some voltage) smoothing caps (no change) and finally through regulator (regulated down to 9V). It works fine and doesn't seem to generate much neat (actually I think it generates less heat than the standard 9V ac way). One thing I am thinking about though is if the dc cable is more prone to pick up noise than an ac dito.

I was thinking about doing exactly that. Just to clarify: you mean your MB-6582 is set up for the C64 power supply option, and you feed 12VDC into your MB6582 where it's supposed to get 9VAC, right?

I wonder if you could do the same with a C64.