ac power vs dc power for neovibe

[rhdwave]

I have been trying an ac wall wart from mouser, but i have gotten a huge amount of noise.  I tried hooking up two 9 volt batteries in series and wallah! most of the noise disappeared.  So, i'm guessing there's some kind of a problem obviously with the ac power.  What i'm wondering is if this could be something as a result of a bad solder joint or a grounding issue, or if it's most likely just the particular type of wall wart i'm using.  I know others have used ac power for the neovibe before. 

I'm thinking of getting a 24v dc wall wart at this point.  If i do this, i'm assuming i can just leave everything as is as far as the diode bridge goes.  Or would it be better to take that out?

Much thanks for any responses! 

[R.G.]

The classical problem with the Neovibe is that people want to put a metal-body power jack into the metal enclosure to run AC into the unit with. This shorts one side of the 24V AC wave to the signal-grounded chassis, while the full wave rectifiers try their best to make signal ground wiggle up and down by one diode worth while rectifying the AC. The solution is easy. Use a plastic-body AC power jack, not a metal body one, and measure to make SURE that the incoming AC touches only the AC pads on the board, not signal ground.

You said "noise" not hum, but your description says "hum" if it goes away with a battery.

[rhdwave]

Thanks R.G.!

It actually is plastic power jack i'm using.  At the moment, the board is not boxed up yet so the jack is not touching anything.  It is just floating from the wires in the air.  Yes, hum would definately be a better description of the sound then noise.  I'll check the signal ground to make sure there's no ac detectable there and get back to you.