question about AC-DC and the Shaka Tube

[Marcos - Munky]

I built a Shaka Tube some time ago, and it didn't worked . Now I was taking another look at my board and the schematic, and saw that it needs 12V AC, and I used 12V DC. Is there a way to make some little circuit to convert my 12V DC power supply to 12V AC?

[Paul Marossy]

Is there a way to make some little circuit to convert my 12V DC power supply to 12V AC?

Basically, no.

[Marcos - Munky]

Well, so I need to search for an AC power supply then. I will take a look at the local store to see if they have one. Or there's a way to modify the Shaka Tube to accept an DC power supply?

[Paul Marossy]

Or there's a way to modify the Shaka Tube to accept an DC power supply?

Unfortunately, the only practical way to get around the AC supply is to design a bipolar power supply for it and rework the Shaka Tube's power supply, in which case, you'll need an AC transformer anyways. It's simplest to just get an AC wall wart from somewhere. I found a 13VAC 800mA wall wart in a thrift store for $1.00 and it works perfectly for mine. 

[Marcos - Munky]

OK, I will search for the transformer next time I buy parts.

[frickecello]

There is a way!  you can open your 12DC Adaptor (disconnect it first!), inside you will see just 3 sections, a transformer, 4 rectifier diodes or a rectifier bridge and a smoothing capacitor, thats all! oh and if its regulated a voltage regulator, what you need to do in order to convert your DC supply to AC, its desolder the wires from the transformer that go to the PCB, then remove the PCB, desolder the wires from the 12VDC output and solder them directly to the transformer wires, check the wiring, and before connecting it to a circuit measure its AC voltage, dont get surprised if you get more than 12V AC (like 17.5 V AC or something) since they will drop while being loaded, I added 3 voltage regulators to my shaka, one for the +15V DC, one for the -15V DC and the last and most important a 12V DC regulator for the heater supply (Im feeding them with 12V DC instead of AC).... I bought a cheap AC-DC adaptor and did this easy mod, hope this help!

[Paul Marossy]

That could work - if you don't destroy the wall wart casing trying to do this mod. I've never felt like it was very safe to hack a wall wart like that unless it's made to come apart.

[Arn C.]

I have also torn a few apart myself.  Some have screws, some don't.  Some come apart rather easily, while others you have to tear them up.  The ones I end up destroying, the cases that is, I just wire a plug to the transformer and put the transformer in a separate box.

Peace!
Arn C.

[frickecello]

hahahahaha very funny  , Im refering to those wallwarts with screws, they open easily without destroying the case (obviously if the manufacturer dont put screws is for some reason), and if you know HOW power supplies work there is no risk at all...

[Paul Marossy]

I just mentioned that because 98% of the wallwarts I have seen are glued together. I suppose if you had a Dremel Tool with a cutting wheel on it, you could do a half way decent job of getting it apart without destroying it.