DIY power supply

[croquet hoop]

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 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?

[croquet hoop]

Bump. Any idea?

[RobA]

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.

[LaceSensor]

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

[RobA]

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.

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.

[ThePastRecedes]

Geofx Spyder?

Pics:

http://www.offsetguitars.com/forums/viewtopic.php?f=11&t=15564&start=705#p642118





Build docs:
http://www.offsetguitars.com/forums/viewtopic.php?f=11&t=15564&start=720#p651703

[aballen]

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.

[ThePastRecedes]

Do you have the build docs for that?

[croquet hoop]

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.

[Willybomb]

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.

[selfdestroyer]

I have always liked this one.. would love to build something like it.
Outside:
http://www.flickr.com/photos/51572438@N05/6130543461/
Inside:
http://www.flickr.com/photos/51572438@N05/6128010985/
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@N05/5764032545/
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!

[croquet hoop]

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

[Peteyboy]

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.

[croquet hoop]

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.

[selfdestroyer]

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.