I'm gonna build a variable voltage regulator in a plastic project box that I can plug 1 of my crappy unregulated(13.whatever volts or more) wall-warts in one side, and have outputs of nice regulated filtered 9.whatever volts coming out the other side(for at home use). Y not just buy some Boss PSA-120s U say? I have no idea. The percocets I'm taking for my bad back R doing the talking right now and they say: "Build A Regulator"!! Besides, it's fun, and I already bought some 317s and 220 style heatsinks off eBay!

Am I crazy? Or is that beside the point?

I'm excited!



RDV

no, you're not crazy, as long as you design it properly.

If you have good protection and a really well heatsinked 317, you could hook it up to a very wide variety of wallwarts and come out with a clean, well regulated supply. You might even consider some rectification and filtering, thus you could even hook up an AC wallwart!

Wallwarts are a dime a dozen at pawn shops, buy 'em up and use 'em I say! This is a great "value adding" idea, dude!  

I bought an equal amount(10 each) of regulators and heat sinks. I'm gonna do the standard regulator circuit. Like on the datasheet, or like the front-end of the small-wart.

RDV

it's worthwhile putting in the two protection diodes. should be shown somewhere on the datasheet.

See the Pedalboard Power Supply and the Spyder Power Supply articles at GEO for some suggested circuits.

The Spyder over at RG's Rock's RDV, take a look at it, you'll like it, I do the same thing under my pedal board's, just make sure you use a good heat sink.
Johnny

Quote from: R.G.See the Pedalboard Power Supply and the Spyder Power Supply articles at GEO for some suggested circuits.

Huh?  I thought it was mandatory to read and study every word at GEO before even posting anything here

Quote from: cd

Quote from: R.G.See the Pedalboard Power Supply and the Spyder Power Supply articles at GEO for some suggested circuits.

Huh?  I thought it was mandatory to read and study every word at GEO before even posting anything here

it is!!!    actually though i did print off everthing i could find before i came here lol, but i am strange.

Quote from: Ansil
it is!!!    actually though i did print off everthing i could find before i came here lol, but i am strange.

Printing out all of the printable articles of Geo(some are quite unprinter friendly *cough*The technology of...*cough* really helps(that's what I did to read on the 18hr flight time between Winnipeg and India)

Anywhoo, back to RDV's question, that's what I did on my Pedal board. It says in the NAT semi Linear Databook 1 that the max inpuit is 28V, so you can say that the input will accept all 1A 12V wallwarts (and 9V if you can find it).Note I say nine as 12V @1A will ouput a lot, and will power a lot of pedals. It's more efficient as if you use a higher voltage @1A supply, because these voltage regulators just slice off the extra voltage, so you will just create more heat(you will still only get reged. 9V @ 1A)

Instructions.
1)first, buy all possible input jack, and tie the positives and negatives together.

2)Buy some LM317's(I'd buy the TO-3 ones as they are 20W)
http://www.national.com/pf/LM/LM317.html

3)ONLY FOR AC take all the AC lines, tie them together to get two main AC lines, and put through a bridge rectifier.
http://www.tpub.com/neets/book7/27c.htm

4)Regulator: look at the first diagram on the LM317 datasheet
http://www.national.com/ds/LM/LM117.pdf
hook up the input like that (as the filter caps are more that 6 inches away(read the datasheet)) Filter the output from this, put it to a variety of male jacks, and you get 9V at 1A

Other regulators(adjustable)
LM317T          15W   TO-220
LM117            20W   TO-3
LM317K steel  20W   TO-3
LM117HVK      huge  TO-3
LM317HVK      huge  TO-3


There you go RDV,

LM250+

I built a voltage regulator to take my 15VAC adapter's output and turn it into 12V dc output for my Shaka Express. That way, I can be lazy and leave the same adapter on my pedalboard and use it for either my Shaka Express or my Shaka Tube. I just use this little box in series with my Express...

Here's a pic: http://www.diyguitarist.com/Images/PS-RadioShack.JPG

I'm just tired of having to work my gig PSA-120 to death in the house. I'm gonna build one with a input jack for the wall-wart, and an output for the regulated voltage that'll run a multi-pronged cord to power 3 effects at a time. I'm gonna buy the smallest RS project box to do it. I may do a pedal board supply like the spyder someday, but not this time. I will make it adjustable voltage-wise however(though I'm gonna run it at about 9.7v). I've got a couple of unregulated "9v" supplys to use with it that just make everything hum as they are.

RDV

Hey RDV, you do know about that 100 ohm resistor in series with one leg of the power supply and 1000uF cap across the power supply trick don't you? That usually kills any powers supply hum pretty effectively...

Quote from: Paul MarossyHey RDV, you do know about that 100 ohm resistor in series with one leg of the power supply and 1000uF cap across the power supply trick don't you? That usually kills any powers supply hum pretty effectively...

These have that already, but I'm gonna add more. Or maybe it's across the AC? I've got some large value caps coming.

Thanks

RDV

Maybe you have some induced hum getting into your system thru your signal path? I was going crazy with a hum problem on my pedalboard for a while. I had like 4000uF worth of filter caps on my power supply but still had a hum.  :twisted:  Then, one day, I realized that my AC adapter was too close to my wah, which just loved to pick up hum from it.   :!:  :idea: Moved the adapter to the other end of the pedalboard, and "voila!", no more hum...

FWIW.

Yup, samething happened to me too.  I made a preamp with the regulated power supply in a separate box with a six foot cord.  On my table, I was testing the thing and the hum was driving me nuts - no matter what I did (more capacitance, different regulators, etc.) the hum was still there.  Once I separated the transformer (I did put in that long cord for a reason) voila! no more hum.

Ricky, to get rid of the " HUM " you gotta teach them the rest of the Song,
:lol:  :lol:  :lol:
Johnny

I've just got some pedals that don't like an unregulated supply. They crackle and hum and carry on, but when I use a regulated supply, everything's fine. Some things(like most of my DIY and the LM386-based amps like 13v+ just fine, but not my Boss or Ibanez stuff.

JD: First I gotta learn that sucker myself! :wink:

RDV

I finally got around to doing this and I must say it turned out quite well, but I've got some questions that I'd like answered if possible.

When I first fired it up, I adjusted the voltage to about 9.5v(unloaded) and plugged in a few effects and it sounded much like it did before. HUM.

So, wondering if this wasn't going to work, I decided to adjust the 10k trimpot I used as the adjusticator on the fly. I dialed it down to where the effects LEDs almost went out, and then brought the voltage back up, up, up, and then the hum went away. I measured the voltage under load and it was about 9.5v exactly and zero hum. I then unplugged the load and measured and got exactly 9v even. Set like this, my old generic 13.whatever volt humming piece of crap is performing like a good pedalboard supply. It works a bit better than my PSA-120 also. A bit less noise.

My question is why?
Why did I have to dial a certain voltage up to kill the noise?
Does it turn the 10uF cap across the + & - into a filter 4 that frequency?

I think this is a worthy project for anyone to try. It'll turn a crappy unregulated wallwart into a nice quiet supply.

Source of schematic: http://casemods.pointofnoreturn.org/vregtut/tutorial-1.html

RDV

what would help would be access to an oscilloscope to check the DC voltage for AC ripple. Then you could dial up/down the regulator and see what effect it has on the ripple.

Maybe one (or more) of your pedals have a problem with too high a supply voltage. Might be worth testing individual pedals for hum at different supply volts.

Not knowing the output impedance of the LM317 (probably quite low)  it's hard to say, but yes, the output impedance and the cap would form some sort of a low pass filter.

thnx for the tutorial link.

Maybe this can help my wallwart learn to stfu...