m00dawg

I was thinking about this and talking with members from my local hardware group - what about using a power resistor? Like one of those huge ceramic square guys (some which heatsinks on them already) capable of handling multiple watts? Yes the voltage isn't constant, but as long as the drop isn't more than 2V above 5V, the 7805 can still work. I can have even less if I use a low-dropout regulator, which only requires .7-1V or so above the output. I'm still throwing out the excess voltage in heat, but it's not all through the 7805. Thoughts?

Damn. Oh well, thanks for the advice Wilba! Do you think there's any use in connected the 7805 to the output of the 7809? Seems like all I am doing there is just moving heat around, but it would avoid supplying 12V to the 7805 directly. I don't think that would avoid needing a bigger heatsink though. I'm going to try my old solution again and see if that heatsink can do a better job. I suppose the absolute worst case is to use two transformers, but I fear that would not only waste a huge amount of space but also get me into grounding trouble all over again (if you remember my failed attempts at using a center-tapped transformer to supply multiple voltages).

I thought about that, although I sure hope it isn't since it's a CrystalFontz, the same LCD recommended on the MB-6852 base construction guide on the Wiki. But it can't hurt to try I suppose. Could be the LCD might be flaky itself, but it does seem odd that it always shows the MidiBox banner without issues *shrug* I need to look into that as well as try Wilba's suggestion of running the LCD off the 9V, which should help my power situation as well.

Yes. I forgot to mention that when I updated the post and didn't remember until I was already heading off to sleepyville. I did indeed disconnect GND. Given the discussion, I have no plans to reconnect it though I still need to cut the wire down just to make sure it doesn't short with anything in the box. My next plan is to see if I can get my old, larger, heatsink onto my newer power board. That or I will hookup my old board the sink is currently connected to in order to see if that helps. The heatsink is from a motherboard northbridge so I'm thinking if that can't handle it then I am probably looking at a redesign. I noticed Wilba used some power diodes for sammichSID to step the 9V from the 7809 down a bit before it goes into the 7805. I might try tha as well. Currently, the 7805 is being supplied by the rectified voltage which means it's getting 12V! :P In previous designed I fed the 7805 with the output of the 7809, but that still should throw off quite a bit of heat and I think I'd be close to overloading the 7809 potentially.

Well...I feel dumb :) I took my PSU apart this last weekend while I switched out the power socket (added in one with a switch since I haven't installed a switch on my MB-6852 yet). Turns out, I had the fuses hooked into the 9VAC side. Whoops. I put them back over to the 120VAC side and now things work as advertised. I did find out that my heatsink is woefully undersized :/ The sink was up to 70C so yeah, that's a bit hot :) My LCD is still flaky though. It's weird - the LCD shows the MIOS boot screen without issue. Once it gets to the patch screen, however, everything goes south. The screen blanks and if I try to change patches it just shows random characters. Sometimes it will sort of reset and I can see things, but most of the time is just garbage. Doesn't seem to be a problem with the LCD since the boot screen always comes up properly. Tried re-uplolading the MB-SID application but to no avail. Other than these two issues, however, my MB-6852 is ready to rock! All 8 SIDs appear to be working without issue!

Haha noted. For now, though, I'm using electrical tape :) Seems to be working well enough - all the live stuff is insulated by tape or crimp connectors. I just be careful when moving it. I plan on putting it in a better case and will actually glue and screw things down.

Yes it is a three prong. I'll go ahead and disconnect it and see what that does, although it does kinda bug me I don't have that thing connected anywhere. Isn't it supposed to protect you from ground faults and the like?

It's my own monster basically. I've got a 9VAC transformer that I take and rectify and supply that as input separately to a 7809 and 7805 that I have heatsinked. Nothing really special, except that I had the luxury of putting fuses on the AC side to avoid killing my xformer (at least that was the plan). I want to make this into a more refined design by adding in resettable fuses (9VAC side) getting a printed board, etc. Right now the regulation is done on a small protoboard, which does mean the possibility for bad ground or shorts is possible. I'm sort of wondering if grounding is an issue here because of the increasing audible hum I hear (when I have the MB-6582 fully stuffed) over the SIDs shortly before the fuse blows. I had tied together the earth GND prong from the AC side to the ground of the board and MB-6582. I assume that was the safest way to do it since the PSU case is just plastic. Could that possibly be it? I was going to test unhooking earth GND to see what that did. I should point out too that, though the heatsink on those regulators isn't ginormous, it's not small either. It does get warm to slightly hot, but not like skin searing hot. So I don't think the regulators are to blame, at least in terms of heat dissipation.

Well, it only happens after adding in the 3rd set of SIDs so it could be something with the MB-6582 itself. Doing a load test is a good idea, although I'll need to figure out how to do that in a way that simulates load form the 6582. Oddly enough, the 6582 is behaving correctly, again, other than the flaky LCD, which is flaky no matter how many SIDs I've got stuff into the 6582. I'll keep playing around with it and see what I come up with.

Wow that is awesome! I love it when companies have kick-ass customer service! Makes such a difference! That said, is Ponoko pretty good in terms of prices for prototyping? For my next project (an MB64 or MB64E - long way away :) I wanted to use an acrylic control surface to save on costs but also for looks since I dig translucent things. I assume, though, that they don't accept Front Panel Express templates? :)

Haha I was wondering about that :) Of course, stupid me, I should've just done the math to figure out the wattage that would have been. No part of the PSU seems to be getting hot that I can tell, other than the regulators which are attached to a dual TO-220 heatsink. The sink is warm to slightly uncomfortable to the touch, but isn't hot enough to burn skin or anything. I haven't touched the caps or regulators yet though, but, at least last I checked, they weren't in backwards :) There's not a lot of parts on a PSU that could go wrong, though, beyond the regulators? My guess is that it is in the PSU itself though. Other than the LCD, I don't notice any flakyness with the MB-6852 itself. Fully loaded with all the PICs and SIDs, power isn't supplied to the MB-6582 for more than a few seconds. With 6 SID, 3 PICs, I have just enough time to test audio from the 2 SIDs on the 3rd PIC by playing a few patches and that's about it. One thing I did notice, however, was that there is a small audible buzz I don't normally hear with only 2 SIDs stuffed. It seems to get louder progressively until the fuse blows, so I have a feeling that's connected somehow.

Yikes that means I'll need something bigger than a simple 7805 it sounds like, which means I have bigger issues than just a fuse :) I thought the SIDs drew more off the 9V than the 5V? Hmm... Well thanks for the help as always Wilba! I'll go grab some 3amp fuses and see how that fares.

It lives! Almost :) Apart from a few minor quirks, my MB-6582 is mostly working. I'm in the process of slowly adding in PIC and SIDs and, so far, everything is working. Problem is, I think I either mis-judged my fuse sizes or I have a problem because once I have 3x PIC and 6x (6582) SIDs, I start to blow fuses. I'm using 1A fuses on the 110V side (on + and Neutral). Seems like that should be plenty. When the fuse blows, there's no odd behavior. My LCD does seem to be flaking out a bit but I don't think that's related (it is flaky well before the fuse blows and is regardless of how much PICs and SIDs I have). Thoughts? I don't want to start putting bigger fuses in the thing until I know it's safe to do so :) I mean the fuse is there for a reason. Thanks!

Sounds reasonable to blame him sure :) On an aside, I noticed those photos appear to have a covering over the LCD? Is that part of the kit or are we on our own for having to figure out that part?

Damn that red looks hot! I would personally prefer a red-tint case myself. If I had the pick of any color, though, I'd probably go for a translucent blue. I used a blue front-panel for my almost sort of working MB-6582 and it looks really nice with amber or green LEDs. Otherwise translucent grey is fine by me. I'm not a fan of the non-transluscent colors though. Them boards are pretty and I want to see thems! Though honestly I'm more excited about being able to build a Sammich more than what it actually looks like. :) So, really, I won't complain if you offer whatever colors you can, particularly if other colors would complicate things.

Good Lord, Wilba, what haven't you thought of! That is crazy! A tiny package that's also takes into account potential future developments. I'm almost scared to ask what your day-job is :) Not that I'm trying to impose any pressure, but I was curious as to when you might be setting up the official bulk order stuff? I want to make sure I put my name down once the Wiki page is up (I assume you were going to do the bulk orders similar to the SID orders?).

Yes you're right, but my thinking was that I would like use core32 for something else in the future. So using it as a 2x2 would get me used to dealing with its changes, etc. But you certainly answered my question! Namely, I should wait for another GM5x5x5 bulk order :) Thanks seppo!

Oh *slaps forehead* sorry about that :) I thought you were trying to answer my questions - I see now you have you own questions in need of answers. Feel free to use this topic for those! I suppose we could even change the subject to "MBHP_CORE_STM32 application questions" or something like that.

Thanks for updating the post :) I was starting to wonder. That said, I'm not sure that answers my questions? To put it more succinctly: Is using the STM32 CORE as a 2x2 USB MIDI interface good enough to be used in production (ie is it stable enough to use in place of my MidiMan 1x1 MIDI interface)? The application code is already on ucapps.de - I just don't know what state it is in and do not want to throw down $50 for a MIDI interface that might not be ready for general use yet. Is it possible to add more MIDI interfaces? I assume the answer is yes given you mention analog input sources, but MIDI requires both in and out and I wasn't sure if it's really the same thing as a normal analog source? Thanks!

My guess is by replacing the 7809 with a 7812 since all the remaining components should only require 5V (only the SID requires 9V or 12V depending on the model).

You can, but I'll go on record as saying I'd prefer a kit :) In fact, I'd probably order a full kit even if I wanted to make customizations since that would seem to be a lot easier that way. If the costs of the kit are marginal, I would say it'd be easier for everyone only to do the kits? But that's just my thought. I've never done a bulk order or anything, but, damn, they look like a lot of work. Huge thanks to everyone who puts those together!

Oh quick question - is there enough room for heatsinks on those SIDs? Similar to the ones used by some peeps who've built an MB-6852? I couldn't tell from the photos, but it looks like a heatsink might be a tight fit. Thought I'd check anyway :) Damnit I can't wait for kits! w00t!

Kit for me! Excellent job Wilba! This thing looks freaking awesome and will be great to have while I am finishing up my MB-6582 (still having trouble with the CS to mainboard wiring - wires keep getting pulled off :/). That and it looks sexah!

I noticed that SmashTV is no offering the MBHP_CORE_STM32 board with the presoldered ARM (yay!!). I was about to pull the trigger on buying one but stopped for two reasons. One, my MB6582 is still not quite complete and I should really finish that guy first; and two, I wasn't sure how much of an early adopter this was? I noticed that only two applications are available - SEQv4 and a USB-MIDI interface. I was quite interested in the latter because it avoids the complexity of having to solder an SMD chip (ie GM5) on my own while still giving me two MIDI IN/OUTs for relatively cheap and gets my feet wet with the STM32. The question I have is whether or not the USB-MIDI application mature enough on the STM32 platform for regular use, or should I wait a bit longer? Also, are there any plans for adding more MIDI ports? Wasn't sure if that was possible using one of the expansion ports? Thanks!

Correct. You can use a single heatsink for the 78xx's as long as they share a common ground. You can't do that with the 79xx since you're dealing with negative voltage here. So the 79xx might be a special case. As an aside, the C64 Optimized PSU design supplies 5V to the ground pin of the 7809 to bump the voltage up to 14V so, in that case, you also would not be able to share the same heatsink between the 7805 or 7809.