I posted this on the TMCC/Legacy forum, but wanted to ask you as well. Do you know why TPC's make post-war American Flyer engines equipped with either diesel horns or air-chime whistles buzz or hum? With a standard AC transformer these engines occasionaly crackle, but they don't buzz and hum all the time like they do when run in conventional mode using a TPC. Does it have something to do with the trace or nature of the AC power generated by a TPC as compared to a post-war transformer (e.g. Flyer 30B) that causes the speaker, condensor, and resistor to react? Thanks in advance for your help with this questions. I've had to disconnect all of these such systems in my classic Gilbert engines (steam, diesel, and electric) in order to run them without driving me and anyone else in the room nuts.

The cap and resistor were figured for 60 cycle current from a AF of Lionel transformer output. These won't filter out higher frequencies from modern transformers. You'll just have to leave them disconnected so they won't drive you crazy!

Sgaugian,
I looked into this several years ago when first built my layout, as I use TMCC, but actually like the original horns/whistles. No one ever provided any solution.

Does anyone know if there is a way around the humming problem? I would really love to be able to keep these engines intact and operate them on the TPC as well.

I did a quick check of the TMCC stuff in the Signature catalog, but no indication of operating frequencies. Basically you'll need to find out what frequencies your power system puts out. If it ranges to 600hz or over, you're out of luck, as that's the operating frequency of the Flyer whistles and horns. If the power frequencies don't go that high, you may be able to buy a different on-board filter for your engines.