Power Supplys?

[BaLaClavaAa]

Well it's about time I built a power supply, and I have been reading about them a bit. First a I wanted to build RG's spyder, but I don't really want to spend that much money. But after reading his article I am a little paranoid of hum  . I then went and looked at GGG's Ultra Clean Power Supply, and I was wondering if anyone had built this and had anything to say about it. Does this hum? Or does the humming only occur when you have too many pedals powered off of one. So like, 3 would be fine, but 8 I would hear a hum? Just in case this was the case I made a vero layout where I could fit 3 of these on (I hope this is cool to make).



Also note cut under D4

Should this work alright? Would it be safe to put 4 jacks on it and build two supplies on one strip board? Will I hear any hum with this? Do I have to do anything different with this to power both types of grounds (like powering a rangemaster). Also if someone could double check me on the layout that would be great =] ( I want to be certain before I go messing with higher voltages).

[GibsonGM]

I'd stick to how it's laid out for us, Bala...maybe adding another jack would be OK, depends on how much current you try to draw from it!  I'm not sure how much current this thing can produce, which is the limiting factor on how many jacks you can have.

Hum is a factor that involves a couple of variables.  Shielding is important (keeping the AC voltage coming in away from ANY signal path, transformers in grounded metal enclosures...), and having the appropriate filter caps there to minimize the ripple (fluctuating DC after the rectifier).  Even where you put the box could have an effect on how your FX react - like playing guitar near a TV set.  If it's very close, you may hear it. 

Putting 2 in one box is probably ok as long as they're spaced apart a little...I would build a separate supply for pedals with + ground.   I'm sure aron will be around to check your layout, I have to head out to a wedding gig (one of those all-day affairs, ugh! At least it's not MY wedding, ha ha).

I think you're on the right track with this one...

~Mike

[petemoore]

  It looks like there are multiple DC jack wires emanating from the board, in the picture.
  Have you scoured around at GGG to try to find out the current supplying capability of the circuit?, that and the amount of current needed = answer to the currents questions.
  My guess is that the transistor would be the component most likely to heat beyond max. temp. by cause of current, take a look at the data sheet on that...
  The Spyder actually breaks ground loops by disconnecting all the PS grounds [all the 9v outputs are floating until plugged into an effect].

[BaLaClavaAa]

Well I looked up the transistor and it says 1.5A output.

I also found http://www.electro-tech-online.com/electronic-projects/28568-ultra-clean-9vdc-power-supply-project.html

Now that said each pedal drew .25A, but I looked at the Voodoo Lab 2+, and it has a few jacks that only give .2A, which would make me think a pedal draws less the that.

Also what transformer should I use for this? So many out there =P

Also, I do play guitar by the T.V., maybe that's why I get that hum 

[sfx1999]

You can't draw 1.5A out of that circuit without a hear sink. The maximum current draw without a heat sink is more like 150 mA.

[BaLaClavaAa]

You can't draw 1.5A out of that circuit without a hear sink. The maximum current draw without a heat sink is more like 150 mA.

Don't they come with heatsinks on? Also how many jacks could I chain on and still be alright with hum and current?

[BaLaClavaAa]

Bump

[Rodgre]

the 317T has a mount for a heat sink, but it won't do much heat dissipation on it's own. You'll still need to attach one to it, and with that tight layout, it will have to be above the regulator, where it might be prone to being jostled and might cause the regulator to eventually break a lead.

You're best to leave room in the layout so that the regulator has plenty of space on the board as to not cause unnecessary heat to the components nearby, and for security, enough room so that the IC can be mounted horizontally, so a heat sink can be mounted to it's tab and screwed into the board.

Like this:


I agree that you need to make sure you have enough available current to power the effects you're hoping to use it with. The more heat sink area, the better chance you have of getting more current without a failure. If you are ready to build, you might want to consider using ONE wire to get from the DC output of your supply to the output jacks, and daisy-chain the + connection from jack to jack instead of running separate wires for each. Because you're not using isolated outputs for each DC jack, there's no benefit to using multiple wires to each jack, and you are actually increasing the chances of a failure because one of the wires has a bad connection or breaks or shorts. One good heavier-gauge wire would be neater and more reliable than several.

By the way, I'm currently using that circuit as my bench power supply and I have multiple outputs available on the enclosure, but I typically only have three things, tops, running from it. No hum. No noise. Steady as a rock.

Hum in power supplies can come from different sources and there are probably a lot of great sites/posts that can explain them. You've already learned a lot from RG's Spyder design (who hasn't? ) The main things to be careful are not enough filtering, which the Ultra Clean circuit does have, and ground loops with pedals at different spots in the chain (say some are on the floor between the guitar and amp, and others are inserted in the amp's effects loop).

Roger

[BaLaClavaAa]

Wow that is big! I see what you mean, I can adjust it to do that.

By the way, I'm currently using that circuit as my bench power supply and I have multiple outputs available on the enclosure, but I typically only have three things, tops, running from it. No hum. No noise. Steady as a rock.

That's a relief, thanks =]. I think I will go ahead and order the parts then, and since it can power more alright I can space out the circuit more. See I thought that the most it could really have was 3, so I needed to cram it all, but if like you said you have never noticed hum then its all cool. Just wondering, but what is the most pedals you have plugged in? Also what transformer did you use?

[ClinchFX]

I noticed that nobody has posted to verify your layout.  As I see it, you have connected the output to an outside pin of the LM317, but the centre pin is the output pin.  There may be other problems, because the symbol on the layout is not the correct one for the TO-220 package, and I can't tell which way round you have placed the LM317.

The LM317 is not a transistor.  It is a 3 Terminal Adjustable Regulator.  Inside, it has something like 25 transistors, a FET, some zeners, resistors, capacitors and a thermistor.  It has thermal overload protection and current limiting, and, under most conditions, it will shut down if it gets too hot, without causing permanent damage.  You don't really have to bolt the heatsink to the PCB as in the picture, and those small black heatsinks will work more efficiently upright instead of lying down.  When I use one of these heatsinks in the upright position, I usually place some neutral cure silicone between the heatsink and the PCB, so that the pins of the regulator are not carrying the load of any vibration.

Most pedals that can operate from a 9V battery will require less than 50mA, so this supply should be capable of running at least 10 of these pedals.  Some complex pedals that don't have battery capability can draw 200mA or more, and it wouldn't be smart to run more than 3 of these without a larger heatsink.  This is just a rough rule of thumb, and there will be exceptions where a pedal requires more or less current than in these examples.

Peter.