Why isn't this working...single adapter for two 9V battery clips

[dave88]

I'm trying to use two of the 1Spot Battery attachments to power an 18v Ibanez AD-80 Delay. It won't work daisy chained with a single adapter 200mA or with two spots on my Furman board 100mA each, but will work if I use two different 200mA adapters. I'd think it was not getting enough current (say it needed 201-400mA) but the Ibanez adapter it uses is only 25mA.

Any thoughts?

[bongomania]

The problem is most likely that it does not in fact use 18V, but rather +9 and -9. One battery is connected positive relative to the "zero reference" (usually ground), and the other is connected negative relative to the zero reference. The reason it won't work with the power supplies you named is that all of their grounds are connected, and all are +9 relative to ground. if you use a supply with isolated outputs (SupaCharger or PPII+ for example) then the pedal will be able to use one of the outlets for the negative reference. It will also work if you use two separate wall warts (that are not powering anything else).

If it does use 18V (+18 relative to ground), then the problem is still that the supplies you named are daisy-chains with a common ground. It is not possible to wire those outputs in series, only parallel. You'd have to be able to connect them in series to double the voltage.

[dave88]

Interesting, it is 18v...unless there's something really complicated going on after the 18V from the Ibanez adapter goes into the pedal,

A regular PPII wouldn't work, just the + ?

[bongomania]

No, a regular PPII will work. Any supply with isolated outlets will work.

[walterw]

Originally Posted by dave88

It won't work daisy chained with a single adapter 200mA or with two spots on my Furman board 100mA each... but the Ibanez adapter it uses is only 25mA.

is that ibanez adapter 18v?

unless you use two different 9v adapters, or a supply with separate isolated 9v outs (not the furman, and not the 1-spot), those two battery clips are just getting the same 9v into both, not 18v.

[dave88]

yes, 18v.
In retrospect I feel pretty dumb about this, although it is kind of surprising that the Furman doesn't isolate.

[dave88]

Turns out there is some complicated stuff going on inside, it gets internally regulated to 12V according to Analog Man, which is probably good since the MN3005 chip maxes out at 18V anyway.

[dannybuoy]

As others have said, it won't work if those 2 separate 9v outputs aren't isolated. If it did work, you could buy loads of battery clips and generate the 1.21 Gigawatts required to go back to 1985!

What you can do though is attach a Godlyke Power Pump or Diago 18v converter which uses a charge pump circuit to double from 9v to 18v.

[dave88]

Perhaps I should be more specific with my actual problem. A BCB-30 board with 3 pedals, 2 are 9V and 1 is 18V. I wanted to power them all with one adapter that fits inside the very little room that's inside the case (as a BOSS PCA does).

[dave88]

Oh, and if that did work we'd still be limited to the around 120V coming out the wall

[dannybuoy]

1-Spot or similar 9v adapter (you can probably use the one you have already if it can supply enough current) and a Godlyke Power Pump fitted to one of the outputs.

I was only joking about the 1.21 Gigawatts, of course that wouldn't work without a flux capacitor. But you wouldn't be limited to the 120v if you ever decide to try though, a transformer would step that up to as many volts as you like. You're better off trying to harness a lightning bolt though as trying to pull that many watts from the mains would blow a fuse and/or burn your house down.

[bongomania]

At a minimum it would damage the courthouse clock tower.

[dave88]

With the power pump I could use the jack, but I'm not sure it would work with the two 9V adapters that I'm trying to use (the jack's a bit dodgy). Would that work okay, setting it to 18v and then splitting it??

[dave88]

Oh and thanks for all the help guys, I really do appreciate it

[dannybuoy]

You just need one 9v adapter with a daisy chain lead (the 1-Spot is a good choice), then use the Power Pump on one of the tips to double it to 18v.

[dave88]

Yes, but I'm trying to make clear: I would then split the 18V line in two and run each split into each 9V battery plug (?)

Really don't want to fry this pedal, you can't get these Bucket Brigade chips anymore

[SGD Lutherie]

You can't run two 1-Spots in series.. they are regulated supplies and would only give you 9v.

Just get an 18V adaptor like this:

http://www.radioshack.com/product/in...Value=Over+12V

[dave88]

Yes we established that, the question now is: splitting an 18V adapter (or 9V "power pumped" to 18v) and putting each line into each 9V battery hookup of an 18V pedal that takes two 9V batteries...is that a bad idea?

[dannybuoy]

Sorry, I now get what you are trying to do! No, you don't want to split that 18v and feed it to two 9v battery clips.

I assumed the pedal had an 18v DC jack, and you would plug the Power Pump into that and forget the battery clips.

Alternatively, if you don't want to use 2 power supplies you could use a the Gigrig Virtual Battery. You should be able to hook up one output of your 9v supply to one of the battery clips and another power supply output to the virtual battery which will 'isolate' it, enabling the pedal to create 18v (or +9v & -9v) from the two 9v inputs.

[dave88]

As I was saying earlier the jack's a bit unreliable so I'm trying to avoid it entirely. Also, as I was saying earlier it takes an 18V that is then clamped or regulated or whatever to 12V.

Hm, short one side out eh?
I'm going to try to dig up a schematic...