12VDC Adapter Noise Test?

[tranceracer]

I just bought a 12VDC 600mA adapter at a liquidation sale for $1.  Tested it with my DMM, Just need to know if it's clean DC.

Is there a simple test to verify if this is clean DC power or unfiltered w/out an o-scope?

This pwr sup has good potential as a PS for my pedal board or power to my future Mansumi Tube pre.  Not bad for a buck.

Thanks!

[George Giblet]

Stick a 1000uF cap on the output, if the voltage on your DMM increases (by a factor of about 1.5, you might see say 19VDC) then there is no filter cap in the adaptor.

[tranceracer]

Thanks George!

[Paul Perry (Frostwave)]

Whether there is a cap in the adaptor or not, and whether the cap is good or not, I'd put a 1,000uF in whatever you are driving (like, on the pedal board) as well. Can't hurt.

[mojo_hand]

In cases of bad power supply ripple, I've also noted that I'd get a significantly higher reading when I'd check its AC voltage than when I'd check the DC voltage.  Do remember to give it a realistic load, though... even a horribly undersized cap will filter a supply with zero load on it.

[tranceracer]

Hey, thanks guys for all the input!!