Well Stan, I did purchase the music take out from a Lionel car and that is in a Christmas box car and working fine.
As far as the MP3 player, now thinking after the fact, I wonder if the squeal might have been caused by picking up power from the track, though it went through the rectifier, the Caps, and the Buck converter. Should I maybe have had a cap on the output of the buck converter? I maybe should have tried a battery input through the track, to see if that may have eliminated the squeal, before trying other things. Looks like I have a lot of maybe's.
As far as the amp goes the directions on the adjustable amp, they recommend not powering it without a speaker hooked up because it could damage the board.
I am looking forward to see the replacement MP3 arrive, now I want to take this to a successful completion.
Still a "Merry Christmas to all", Christmas is much more than trains and gifts.
Ray
