..
@vroberts posted:..one small issue; the polarity in the simulation is reversed relative to the measured waveforms from A and B to U.
Depending on the service info you used to build the simulation, you probably have the diodes in the simulation reversed. The positive offset is correct, the diagrams for several transformers in the service documents show the wrong rectifier orientation.
This didn't matter from 1934 until 1972 when the electronic whistle was introduced, as the old relays were not polarity sensitive.
@Santa Bill K posted:My ZW had the discs replaced with new disc and the rollers replaced before I got it. Air whistles do fine, however; modern tenders and Lionel Sounds only start and stop the bell when the whistle lever is activated. How can I change the polarity on the whistle lever to work on modern tenders?
The person who did the modification followed the erroneous schematic and installed the diodes backwards or used cathode-to-case diodes instead of the correct anode-to-case diodes.
