If you have a newer transformer with whistle and bell buttons on it, such as the MRC AH101, one of those buttons should activate the the DC relay in the 314AW tender. These all operate on the same principle. They apply a DC offset, around 4V, to the AC sine wave. On new 2 button controllers one button applies a -DC voltage, the other a +DC voltage. I can use those buttons on my AH101 to activate the whistle and bell functions on my modern Legacy engines without the need for a Legacy control system. Reversing the direction of engine travel on the track changes which button activates each function.