Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Can you guys tell me what basic parts I need to construct a 9 volt DC 500mA power supply?  I live in United States and my home socket voltage is : 118 volts AC.  

I see after reading about wall warts / AC adapters on Google that some are straight AC, some are rectified AC, some are rectified and smoothed AC.  Any way to tell by the picture which category this adapter falls into?  After messing around with some more complicated audio projects and not getting acceptable results I'm beginning to realize how much I don't know about electronics.  I thought I'd give this project a try because it should be simple, right?

I attached a picture of the transformer back label for all the technical specs I have.  This power supply powers a Studiologic keyboard controllerhttp://www.studiologic.net/sl-990xp.html (http://www.studiologic.net/sl-990xp.html).  Thanks

Hi Zappacat,
                 You have a 9VDC 500mA adaptor.

Obviously a SMPSU ,, you can tell by the dual AC mains of 110 to 220 V primary.

These suckers can be horrendiously noisey buggas depending on how well they are designed and how prone the circuit it powers is to picking up noise.

IMO play it safe and use a wall wart with a *RealTransformer*.

SMPSU's may work on some gear but may spell trouble when mixing and matching pedals in front of higain amps.

Sounds like you need to get some bedtime reading on the basic's of power supplies.  ;)

Go here; http://evatco.com.au/hamptchoke.htm

Click on transformer *selection guide* halfway down

Direct try this: http://evatco.com.au/ham_files/hampwrselect.jpg

Now ***SAVE IT*** Print it,,, as you progress you will fast come to see how useful it tiss.  :tu:
Should be mostly self explanitory,, oh remember the *I* stands for current.
Cheers Phil.

Will either of the pictured power supplies work as a substitute?  The issue that really concerns me is the Amperage discrepancy.  If something goes wrong in the keyboard would the circuit start pulling more current than it should due to the increased amperage capacity of either transformer?

I get voltage readings of 9.6 volts for the Philips transformer and 12.6 volts for the ENG transformer.  The Philips transformer is VERY light and small.  Similar to a cell phone charger.  It feels like it doesn't have any coil in it.  The ENG feels like it has coils in it.  Would the ENG be giving me a higher voltage rating because there isn't a load on it when testing it with my voltmeter?

Thanks.