I have an old ZW transformer that I would like to sell, but I no longer have any Lionel engines to test it out. So, I measured the waveforms using a 22 Ohm load resistor.
All four outputs provide nice sinewaves under normal run mode; however, the whistle waveforms seem strange.
Based on a schematic diagram of the ZW which I found on the Internet, and have attached, I would have expected the A and D outputs to be sinewaves with a DC offset when the whistle mode was activated. And, in fact, that is what I see when I simulate the circuit in LTSpice.
However, the measured waveforms are half-wave signals instead of offset sinewave signals. I've attached the A and D whistle waveforms, and the normal run mode waveforms at full output.
Can anyone confirm what the whistle waveform should look like?