Further questions about triggering Whistle/Bell

[fifedog]

Z4000

White button = whistle

Yellow button = bell

I think that about does it.

BTW, cool name.

[BobbyDing]

I have a question about our present train transformers and how they trigger the whistle/bell. I understand how the CW-80 triggers the whistle/bell by altering the ON time of the sine wave (soory about the bad terminology), and I understand how the older PW transformers did this (like my little 1033's) by adding a DC offset. But how about the other high tech transformers that are out now, like the z-4000 and new ZW. That is, what methods do these newer transformers use to trigger the whistle/bell? What are the electronics? Same as the PW (Diode/Resistor wire), CW-80 (varying the chopped sine wave), or another method completely?

Thanks,

Bobby