9 Volt voltage regulator for my stomp boxes.

[KMS]

I have read a bunch of files on wall warts, and all the ways to avoid the magnetic loop that causes the hum etc. And I don't like what I read about this stuff.

I had the idea that a big 9volt battery would work just fine for me since all my stuff is mounted to a dolly anyway and that way I could just hook up to a charger for 24 hrs once a week and I'd be set, with pure DC.

Well, I can't find a big 9volt battery and started wondering about a voltage regulator for a big 12volt battery instead.  I have found some sites with schematics for some nice regulators but the best I can find requires at least a 2.5 volt difference from input to out put voltage.

Does anybody have any ideas here about dc/dc conversion from 12V step down to 9V?

I would love to walk into practice next week with all my stuff on my dolly and not even plug into ANYTHING, AND JUST START PLAYING.  The guys would have a fit over that!

[R.G.]

You actually have a couple of options. You could use a 12V battery and regulate it down to 9V with a 7809 three terminal voltage regulator chip.

However, it's even simpler to find a battery holder to hold six D cells and get 9V directly that way. D cells will last a long time in effects usage.

[niftydog]

DC/DC convertors are not trivial to design and build. You can find commercial 12-9VDC/DC convertors, but usually not at the required current for an application such as the one you suggest. (in fact, I have one right here that I salvaged from an old LAN card!)

Decent regulators with low dropout voltages can be built that will suffice, but regulators chew power as well remember!

Perhaps a cheaper option would be to build a few common cells into a battery pack ala RC cars etc. Half a dozen D cells and you're set.

Still, seems to me that it would almost be less hassle to just build the Spyder and be done with it!

[mjarus]

I actually power all of my experiments with a 12V 500ma wall wart running into a LM317 fixed to 9V.  I use 1% resistors of 200ohm and 1240ohm to get to 9V.  In addition there are a few caps involved for smoothing and stuff.  Look at the data sheet, they have the circuit listed.

I do have some LM7809s, but I haven't used them because I heard that the LM317 is more stable.  Is there any truth to that?  Dunno.  I do know that the LM317/Wallwart is pretty darn "quiet" so far.  I don't have to heatsink the LM317 with 12V either.

As niftydog suggested I am going to build a Spyder-like PS soon, but I think I will actually build 2 or 3 taps @ 12V so I can run a variable LM317 that I can dip down to like 7.5V to play with the whole "brown sound" thing and another couple of taps @ 18V to mess with the "high power" projects.  Haven't thought it all the way through yet...

mjarus.

[Mark Hammer]

I second brother Keen's suggestion about a sextet of D-cells.  Unless your plan is/was to power a bunch of current-hungry digital effects, those batteries should last you a while (me fuzz you long time), and it's hard to get any more humfree than pure DC.  If you can't find a 6-D holder, you can probably find a 4-D and 2-D and wire them in series.

Why that option and not the huge battery?  Well, as noted, D-cells can deliver substantial amounts of current for respectable periods of time (certainly reliable enough for a gig).  Second, the holder/s can often be easily secured to a/the pedal-board by a wood screw or two.  Third, they use 9v battery-snap connectors, so "turning the supply off" is as simple as yanking the connector off.  Fourth, they have a pleasingly low profile, which makes for pedal-boards you can pack away (my hunch is the battery you were pondering has a much higher profile).  Fifth, you can pick up such batteries just about anywhere, often in "dollar stores", and where the lifespan difference between a cheap 9v and a high quality 9v may be substantial, the difference between cheap and expensive D-cells is not something you'd likely notice unless you were powering lanterns or other devices demanding tons of current.

[KMS]

The D Cell ideas are great RG and Mark.    I don't know why I didn't think of it.  Yea Mark, I was considering a large acid battery which would work on my dolly full of gig stuff, but the D cell idea is much better.  Radio Shack has metal hydried rechargeable D cells so I might look into that since my 9v rechargables have lasted me about two years (and still work now but loose their charge in about 5 days instead of two weeks)

Thanks everyone for your suggestions, as usual you guys have all the answers anyone could want.

[petemoore]

  If all your components are rated at say 16v and higher, you can run them on 12v without worry.
  D Cells sound like a really good solution, rechargables...I like the NiMh's.
  I collected some alarm batteries, brick sized...they charge up to about 14 volts and last...and last...and..last...but not least,
  ...OT... I bought a 'silent' Visual Sound One Spot adapter, it puts out 9.7v, and is noiseless...completely...so far...from what I've read and experimented with, I did have to invert the output polarity and daisy chain it...couldn't be happier...relatively inexpensive and easy to do...drilling adapter jack holes in already built boxes sukks without a drill press though...the bit 'screwed' into my BMP !!! OUCH...it doesn't *look broken.

[KMS]

  If all your components are rated at say 16v and higher, you can run them on 12v without worry.

Yea I thought about that, but many diodes could have problems particularly the LEDs.  It is doable with some modifications, but I pretty sure I'm going with the D Cell batteries.

Our Bass player works at a electrical box manufacturer and he just made me a 12"x24" (18 or 16 gage not sure).  They made it with no knock-outs and a hinged lid for quick access to the circuits.  It has about 7 degree angle on the top and is about 1 1/4 tall in front and about 2 1/2 inches tall in back.  So I am in the process of consolidating all of my FX into this one big foot panel.  I'm going to take my time and design a good layout that will allow for future expansion.  One of the things I'm need to find out now is how to make the graphics look professional.  I will post a pic of the box later tonight or tomorrow.