Hi.
I'm building a 9v stabilyzed power supply (1A, I think)
The problem is: I have the internal transformer 220V - 12V, and there are 4 points to connect it: 2 are 0 - 220 and the others 2 are 0 - 12. How to connect them to my circuit? I have just the positive and negative pole from the adjust bridge (?) and the cable from the switch.
Thank you

Federico

Coil 1
220 goes to the hot wall connection  
0 goes to te cold wall connection

Coil 2
12 goes to your voltage regulator etc.
0 goes to ground

The rectifier bridge will have 2 connections for AC, most likely labeled "~", that's where you connect the 12V wires from the transformers. The "+" and "-" terminals on the rectifier go to the filter cap and voltage regulator etc...

Just be careful when dealing with 220V  

also don't be confused about the 0 and 220: the transformer doesn't know which is which, it just sees 220V AC between the two connections.
If this wasn't the case, you'd have to really be careful not to stick a plug in upside down (reversing hot and cold)
So: just hook up 220 (with a suitable fuse !!) to the 0 and 220 lines as stated, and work *very* carefullt so as to avoid ever having your guitar strings hooked up to mains.

I know, there are two connectors like ~ , but where I have to connect 12 and where 0? Is it the same? Where 12 and where 0? The connectors on the rectifier bridge are similar: there is the same ~ item on them..  :?
Then what do you means for hot wall and cold wall (for 220 and 0 connections)? :?:

http://www.generalguitargadgets.com/v2/index.php?option=displaypage&Itemid=106&op=page&SubMenu=

Thank you guy!  :wink:

"~" is a symbol for AC, alternating current, so there is no distinction made between voltage polarity, you can connect the 12 or 0 cable, it doesn't matter. Same for the transformer, just take your power plug cord and connect it to the primary side of the transformer (220/0).

Just found this page, has it all explained:
http://www.kpsec.freeuk.com/powersup.htm