LIONEL KW TRANSFORMER

[bigkid]

I have a Lionel KW need to replace the Seleniuem Rectifier with a more modern SCR Diode. I spent 40 years in HO DC was easy this ac is mind boggleing. Can some one here give me some help with this.  THANKS    BigKid

[lionelsoni]

Unless your rectifier has failed, you're better off keeping it.  It has a lower forward voltage than a conventional silicon rectifier.  A Schottky diode would be a better match.

The original diode is copper-oxide, not selenium.

A silicon-controlled-rectifier (SCR) makes no sense.  I think you may have meant to type just plain "silicon".

Whatever you may put into your transformer, be aware that the schematic diagrams for older Lionel transformers show the diode symbol reversed.  If you put your replacement diode in backwards (that is, according to the schematic), it will still work with traditional whistles and horns that use a slugged relay, but whistle and bell functions will be swapped for modern locomotives.  [To be clear, the arrowhead part of the symbol on the schematic should point toward the anode, not the cathode.]

That last sentence is not clear at all.  Just imagine the diode symbol on the Lionel schematic to be reversed end-for-end.

[bigkid]

Thank Bob : I'll just leave it alone and when and if it needs replaced I''ll get a Schotty thank you for help. Being well versed in electronics & electrisity and yet I still need help with this AC system.