AC to DC transformer convertion

Are you looking for a variable DC output or a fixed voltage output?

@OriginalMadman posted:

I recently picked an older CW80 Lionel transformer and its not working correctly. Its putting out voltage but it jumps from 1.5 volt to over 16 in an instant...

With a train or a meter attached?  Let's see a picture of the meter.

The process of making direct current from alternating current is called "rectification."  The reverse, DC to AC is called "inversion."

Rectification is as simple as putting a diode (also commonly called a rectifier) in series with one lead of the AC output. That gives you half-wave rectification. That means that as the AC goes from + to - 60 times a second, the top half (or the bottom half) of each cycle gets cut off.

The next method is called "full wave rectification." That uses 4 diodes in a "full wave bridge."

Finally, if you want "filtered full-wave rectification" that can be accomplished by adding an electrolytic capacitor to the output.

If you google any of those terms, I'm sure that you will find a plethora of diagrams and explanations, including wave form illustrations that explain it better than I did.

DC supplies are dirt cheap / free.  If you are not familiar with electrical terms and concepts, you would probably be better off buying a supply that does not start off with one foot in the grave.

I'm going to guess for most purposes, he may want regulated voltage, and perhaps a variable voltage.  A statement of requirements would be very useful.

When my CW80 went belly up, I found it too difficult to work on the PC board because of its positioning in the case and difficulty removing. I decided to junk the CW80 but save its 19 VAC transformer.

You can then take a cheap 2A AC-to-DC voltage regulator board from Amazon, or wherever, to produce a DC voltage anywhere in the 0 to 12 VDC range.