I would like to build a power supply for my pedalboard, but I'd rather avoid messing with 220v. So I've come to think that something like that (http://topopiccione.atspace.com/PJ25TPCMedusa.html) could be interesting (basically, a row of 7809 voltage regulators fed by a 12-19 V switching power supply). What can I expect from such a design (compared to the ubiquitous 1Spot for instance)? Do you see any major reason I should stay away from it and choose something else?
Bump. Any idea?
The idea should work. The issues I see with it are that the outputs aren't isolated and switching power supplies are noisy to begin with. They do obviously work though since that's what nearly every pedal power supply is based on.
One of the things to think about though is the inefficiencies of the voltage regulators. You are going to be dropping a lot of power across the regulators. So, your input DC power supply is going to need to supply quite a bit of current that is wasted. It'll be bigger than it otherwise would need to be.
The DC brick type power supplies that I have use buck converters (or buck regulators) instead of the normal regulators. They are more efficient. But, I think they also add more noise themselves and that's the component that died on one of my bricks.
I've built a bench supply that uses a 12VAC output wall wart supply and then rectifies it and I use a 5V regulator and 9V regulator to get those outputs and then a couple of LM317's to get variable between about 4V and 15V. This works fine for my bench and is very quite. But, It has the problem of the inefficient use of the regulators too. So, it could become an issue with something like 8 outputs. If you only wanted 9V outputs, you could get an AC/AC transformer that would rectify to a better output voltage and this would work well.
It still wouldn't have isolated taps though. So, we were talking in another thread here about using 2:1 and 1:1 transformers with the same basic idea to get more efficient power usage and isolated outputs. I think this could be a really neat way to go. I've been looking for the right transformers to use and I think I have some that will work. But, I don't know enough about transformers to know if I've got every spec covered. If that part can be solved, I think this would be a really nice solution -- no high voltage, efficient, clean, isolated and not very expensive.
When you can buy the Fame DCT-200 for around £60 or less I really struggle to see the point of building power supplies.
This model is fully isolated, has 12v AC and DC outlets, 2 sag outlets, 4 standard outlets (100mA) and 2 high power outlets (250mA)
Just cant be beat.
Sold under different brands in other territories.
ymmv
Can't the same thing be said for pretty much any pedal now? It's kinda the spirit of DIY to want to build it yourself. Besides that, for me, it's another learning experience.
I hadn't seen the Fame units before, so I googled it. I found this link http://freestompboxes.org/viewtopic.php?f=16&t=15737. (http://freestompboxes.org/viewtopic.php?f=16&t=15737.)
The photos don't really make me want to get one. More to the point, it doesn't do what I need. I don't want 12V outputs. Using 12VAC rectified to around 16VDC and then regulated down to 9V is inefficient. It doesn't have 15V and 18V outputs, which I do want. The commercial power supplies that do have what I want are up over (US)$200. The bench supply I built was closer to (US)$30.
Geofx Spyder?
Pics:
http://www.offsetguitars.com/forums/viewtopic.php?f=11&t=15564&start=705#p642118
(http://i247.photobucket.com/albums/gg133/mysticwhiskey/DIY%20Pedals/InsektPowerSuppleSmall_PCBFrontAngled.jpg)
(http://i247.photobucket.com/albums/gg133/mysticwhiskey/DIY%20Pedals/InsektPowerSuppleSmall_FrontAngled.jpg)
Build docs:
http://www.offsetguitars.com/forums/viewtopic.php?f=11&t=15564&start=720#p651703
Here is mine.
http://s1200.photobucket.com/user/bitracer/library/Pedals/Pedal%20Powerr?sort=3&page=1
I actually put boards up on oshpark, you would need two for 8 outputs. Each is isolated, very stable and well regulated. Uses the weber transformer.
http://oshpark.com/profiles/aballen
Of course you can etch your own like I did.
Do you have the build docs for that?
Thanks for the answers everyone, they give me food for thought. Lots of great projects here! But there does not seem to be a way to have isolated outputs without a transformer, which I hoped to avoid since in my mind, transformer = 220 VAC (which I did not want to mess with) to low DC voltage. RobA's idea with 1:1 transformers looks very appealing though, I'd really like to know more about it when someone comes up with a design.
I feel your pain trying to make/find something for your requirements. I ended up making my own:
http://www.madbeanpedals.com/forum/index.php?topic=9871.msg87154#msg87154
Basically because I needed a 18vAC outlet along with the 9vDC stuff and everything retail was too expensive. I think you could feed the 9v rectification/regulation section with pretty much anything and still get your 9v at the other end - I've considered running it off laptop power supplys myself. It'd work.
I have always liked this one.. would love to build something like it.
Outside:
http://www.flickr.com/photos/51572438@N05/6130543461/ (http://www.flickr.com/photos/51572438@N05/6130543461/)
Inside:
http://www.flickr.com/photos/51572438@N05/6128010985/ (http://www.flickr.com/photos/51572438@N05/6128010985/)
http://www.flickr.com/photos/51572438@N05/6302737426/ (http://www.flickr.com/photos/51572438@N05/6302737426/)
Looks like there are a few pics of the build process also.
http://www.flickr.com/photos/51572438@N05/5764585224/ (http://www.flickr.com/photos/51572438@N05/5764585224/)
http://www.flickr.com/photos/51572438@N05/5764032545/ (http://www.flickr.com/photos/51572438@N05/5764032545/)
http://www.flickr.com/photos/51572438@N05/5764582514/ (http://www.flickr.com/photos/51572438@N05/5764582514/)
Info:
5 -completely- isolated 100mA 9V outputs, and two input jacks so that you can plug power into one, and use the other jack to run said power to a second unit. You know, in case you need more outputs. Also, it's TINY. It fits in the palm of your hand, and hardly takes up any space on your pedalboard. Or bedroom floor.
There's a DIP switch on the back to turn off up to 4 of the outputs. Any output you're not running should be switched off, since the chips tend to run hot with no load. You'll know if an output is on because there's a fancy white LED above each jack.
One more fun feature-- since it uses a 5V DC supply, you can use the Team Tesla to power a few pedals with your laptop for wireless power! You'll want to limit it to two outputs, probably, but it's a pretty neat thing when you're out and about!
This one looks very interesting too (and the man has exceptional building skillz, his flickr gallery is incredible), thanks for the links, I'll try and see if I can find more about it.
edit: found it, third schematic in the first post http://www.ilovefuzz.com/viewtopic.php?f=151&t=21891
I've been in the process of building one of these too. I work as a student computer repair tech and am fortunate to have access to several unwanted laptop power bricks. I have tested 5/6 for low disrtorrion and they all seem to be ok. My plan was to just like you was to use 78** to drop the voltage down ( it comes out of the power supply at 15- 19 V depending on the model). I plan on mounting this all in a cheap holiday food tin. All parts should be <$20. You can also by replacment laptop power supplies relitivly cheap on amazon.
I've got one which has been sitting idle for a few years now, and a few of these 78xx regulators, so I guess I'll give it a try for fun, and keep a eye on better solutions.
Quote from: croquet hoop on August 30, 2013, 09:56:14 AM
This one looks very interesting too (and the man has exceptional building skillz, his flickr gallery is incredible), thanks for the links, I'll try and see if I can find more about it.
edit: found it, third schematic in the first post http://www.ilovefuzz.com/viewtopic.php?f=151&t=21891
Thats the same one I posted also.. McSpunckle makes some awesome pedals. The Tesla looks really cool and its in a 1590B and you can chain them. Sounds like a win.
Quote from: RobA on August 29, 2013, 03:07:14 PM
Can't the same thing be said for pretty much any pedal now? It's kinda the spirit of DIY to want to build it yourself. Besides that, for me, it's another learning experience.
I hadn't seen the Fame units before, so I googled it. I found this link http://freestompboxes.org/viewtopic.php?f=16&t=15737. (http://freestompboxes.org/viewtopic.php?f=16&t=15737.)
The photos don't really make me want to get one. More to the point, it doesn't do what I need. I don't want 12V outputs. Using 12VAC rectified to around 16VDC and then regulated down to 9V is inefficient. It doesn't have 15V and 18V outputs, which I do want. The commercial power supplies that do have what I want are up over (US)$200. The bench supply I built was closer to (US)$30.
ok I can agree on the functionality aspect but making a PSU is quite hazardous compared to a tubescreamer, hence my choice to just buy one.
Building a fully isolated one with all the features you want it might just be better to buy a commercial one was all I was thinking.
Quote from: LaceSensor on September 01, 2013, 10:25:44 AM
...
ok I can agree on the functionality aspect but making a PSU is quite hazardous compared to a tubescreamer, hence my choice to just buy one.
Building a fully isolated one with all the features you want it might just be better to buy a commercial one was all I was thinking.
I agree completely if we are talking about using a mains input power level. But, there are a couple of different paths that are possible that use a low voltage input and those are interesting. Now, if I can only figure out which transformers are the right type to use to isolate the taps, I think we can come up with a nice and reasonably priced DIY friendly board. The problem is that I'm finding that I'm going to need to learn a whole lot more about transformers than I really wanted to know to be sure the design is correct and safe. Oh well. Anyone have a good source of info on transformers thats aren't aimed at kV levels.
I think we have a good base with the Team Tesla! schematic... now the design could be more efficient, and I'm not sure where to find the Recom converters (Mouser does not stock them), but maybe the design can be adapted while keeping the basic idea.
Not only do they not stock them, they charge $7.07 per each when they do have them in stock.
But, I don't understand the point of the design to begin with. Why start with a 5VDC input and use a switching upconverter to boost the level and add more noise? Using multiple clocked converters has issues as well. Using the common mode chokes may well help with this, but I still don't get the point. It would be much more straight forward to just start with a 1.5A 12VDC power supply and then use the regulators and common mode chokes to regulate and filter. The only thing I can come up with is that the 5V is because it is a universal USB charger power level. But, that doesn't really seem like much use for this purpose.
Edit: Of course, I could be reading the data sheet wrong and completely missing the point. I'd be happy to hear that too ;D.
Quote from: RobA on September 01, 2013, 02:53:27 PMBut, I don't understand the point of the design to begin with. Why start with a 5VDC input and use a switching upconverter to boost the level and add more noise? [...] The only thing I can come up with is that the 5V is because it is a universal USB charger power level. But, that doesn't really seem like much use for this purpose.
From what I read, it's pretty much the point: 5V chargers are common, and powering pedals from a USB port is fun and can be convenient. I won't dispute that, although I agree with your objections—I find it more logical to start with 12-19v and regulate down voltage.
Looking around Mouser, there are other very similar DC-DC converters to the one that is specified that are in stock. The cheapest I see are around (US)$5 per converter. It's going to get pretty expensive to build a multi tap supply if you want to isolate every tap. But, I do think it would be possible with the parts that Mouser does have.
Quote from: croquet hoop on September 01, 2013, 03:15:49 PM
...
From what I read, it's pretty much the point: 5V chargers are common, and powering pedals from a USB port is fun and can be convenient. I won't dispute that, although I agree with your objections—I find it more logical to start with 12-19v and regulate down voltage.
I can see that. I'm not sure of what is happening in the DC-DC converter yet, but they are isolated according to the spec sheets. So, that would be part of the reason too. Especially if they provide total isolation so you can invert the polarity and such without causing shorts. Still, they are expensive.
Also there is the AMZ Power boards. Looks like this member made one
http://www.madbeanpedals.com/forum/index.php?topic=5430.0 (http://www.madbeanpedals.com/forum/index.php?topic=5430.0)
Quote from: RobA on September 01, 2013, 03:22:41 PMI can see that. I'm not sure of what is happening in the DC-DC converter yet, but they are isolated according to the spec sheets. So, that would be part of the reason too. Especially if they provide total isolation so you can invert the polarity and such without causing shorts. Still, they are expensive.
They are, but if it's what it takes to get an isolated & regulated power supply without messing with AC mains, I find it to be an acceptable tradeoff (and I can't see it being more expensive than any equivalent psu commercially available anyway). Of course, there may be better designs, and I am curious about possible improvements of the idea.
Bump. In spite of the shortcomings of the design, I've just ordered what's needed to make a small Team Tesla with two isolated outs to give it a try and see how it performs. I'll let you know how it turns out.
I'll definitely be interested to hear how this turns out. If an isolated DC-DC solution can be made to work well, it could be really useful when used with some of the Li-Po battery packs that are available now.
Although the tonepad power regulator isnt isolated like the one suggested by Lacesensor, it costs the whole part of about $10 to make (in a 1590a), so it actually is cheaper in this, well...unfair, comparison.
Check that one out if you want a super simple and safe power supply to build. If you havent seen it, heres a couple of videos i uploaded recently:
Demo:
http://www.youtube.com/watch?v=ROZvdRb01d4&feature=c4-overview&list=UUGhzS1GbX-yxyBrUJtnUMoA
Build report:
http://www.youtube.com/watch?v=KTb2FZDkvD8&feature=c4-overview&list=UUGhzS1GbX-yxyBrUJtnUMoA
Paul