Neovibe/GGG Isolated Power Supply Question

[blues_mang]

I'm building a new pedal board for all my modulation pedals and want to use Scott Swartz's 4 isolated power supply to power them, including a Neovibe. I planned on using an 18V transformer to power the Neovibe but noticed that the max. current output of the voltage regulator is only 100mA. Is that enough to power the Neovibe? If not, could I possibly combine 2 outputs to double the mA or am I way off base?

[axg20202]

100mA is unlikely to be enough. IIRC, something rated at 200mA might also be a bit underrated for powering a neovibe - it is quite a power-hungry circuit. You'd be better off finding a regulated transformer that is rated for 500mA or so, which would easily power the neovibe.

[Auke Haarsma]

If the transformer can provide enough mA, consider using 7818 instead of 78L18.



This one can provide up to 1A (1000mA) if I'm not mistaken.

[RedHouse]

I've used 7815 and 7818 units without a problem in my vibe builds, but then again, I use a 20mA bulb.

[Auke Haarsma]

78Lxx = 100mA unit
with out the L (78xx) = 1A.

Keep that in mind.

[fpaul]

I use this ps on my with 12 50ma bulb; works great

[blues_mang]

Thanks guys for some insight.

This was the transformer I was going to use: http://www.mouser.com/Search/ProductDetail.aspx?qs=mZMNBqyh7oHqVNDbRmaL%252bQ%3d%3d , but it looks like in parallel, the max. output is still only .13A. Anyone know of a link to a suitable transformer with higher max. current output that would work with this layout?

fpaul,
which transformer did you use? My bulb is a 1.5V, 25ma. If you used the same one, I'm guessing it will work with mine since it is a lower current.

[fpaul]

I used the ones specified for 18 volts, on the ggg page, at the bottom.  It was from mouser.  I used the 1.5v bulb first,( and didn't like it), but it blew before I finishished building the ggg power supply.  No problem with the new bulb using the ggg power supply, and I've been playing almost everyday for probably over a month.

[blues_mang]

Thanks fpaul, I'll give it a shot.

[dxm1]

So many choices... here's one:

http://www.partsexpress.com/pe/pshowdetl.cfm?&Partnumber=120-1165&CFID=14088281&CFTOKEN=64247603

If you plan to power several effects, you will probably want to look for something in the 1-2A range.

[fpaul]

dxm1 has a point.  If you just want to power the univibe there are a lot of easier options.  I ran mine for a while on a 24vdc 600ma from altex, $9.  Just have to adjust the bulb bias (brightness).  I couldn't tell alot of difference in sound although it was a lot brighter with the 24vdc.  With the bulb you're using, I don't think brightness will be an issue; I think mine was too bright with the 1.5v bulb.  The univibe board has filtering and voltage regulation already,although it's not regulated to the bulb.  I put 3 of the ggg power supplies in one box(ala R.G.'s spyder) and mounted it under the pedal board with pieces of bicycle chain links so I have 4 x18v and 8x9volts; I got really tired unplugging all the stompboxes i've built everytime I played my guitar.  Positive and negative ground boxes run on it together without a problem.

This is OT, but you'll probably want a booster to match the univibe volume with other pedals, if you don't have one.  I built the colorsound overdrive because I read Gillmour used one; there is a great layout in the layout gallery and it was an easy build.  I really like it and it works great after the univibe.

[blues_mang]

fpaul, yeah that's exactly what I'm looking to do. Right now, I'm running the Neovibe off a 24VDC "wall-wart", but I plan on stringing 2 of the GGG boards together in 1 enclosure and mount it to the back of the new pedalboard I'm building with an on/off switch. I plan on having 18Vx1, 12Vx1, & 9Vx6. I planned on using the secondary of the 18V xformer for a 12V output, although I don't have any 12V pedal at the moment.

dxm1, thanks for the link, but I was looking for a split-pack x-former that could be used on the GGG isolated PS board.

[blues_mang]

Well, I finished my GGG power supply and it works, but as I was afraid of, it doesn't seem to be powering the Neovibe. It lights up the LED's in the pedal, but I'm not getting any swooshing, so it's not driving the bulb. I checked the voltage on the power supply and I'm getting just about 17.96V. Anyone know of any other split pack transformers that would work that would put out more current. I'm guessing the draw of the Neovibe is more than this one can handle.....or, I'm doing something wrong. Anyone have any ideas? I'm kind of bummed because I purposely made this power supply so I wouldn't need a separate wall-wart for the Neovibe.

[petemoore]

I checked the voltage on the power supply and I'm getting just about 17.96V.
  What was the load during the test ? Circuit connected, 17,96 I'd think it'd fire up the opamps in the SP, and everything else.
Anyone know of any other split pack transformers that would work that would put out more current.
  The only reasons I can think it wouldn't work is if the voltage drops when the load is added and the voltage drops because the current draw, or the transformer drops out of the game because the current limitations were exceeded and heat built up, or some arcing, I've never seen arcing in these little transformers.
  I'm guessing the draw of the Neovibe is more than this one can handle.....or, I'm doing something wrong. 
  Anyone have any ideas?
   
  Measure the voltage drop with and without load on the power supply.
  Take some general circuit voltage measurements.
  Measure the current draw of the actual circuit at the power voltage supplied, compare that to the rating on the PS.

[blues_mang]

Pete, I'm not sure how to measure the voltage drop or current draw.

[blues_mang]

Ah, I figured this out.  The original power supply I was using was a 24VDC and didn't realize I had to re-adjust the trimmer for the bulb bias for the lower voltage. Once I blew the bulb, replaced it, and adjusted it slowly, I got it working perfectly.