I ran across a post where a gentleman wanted to run an Mth Protosound 2 Engine using his old ZW transformer. The horn/whistle button works but he has no bell button. Aside from purchasing a new transformer what is the bell signal? A whistle signal is just a DC pulse . It sounds like an interesting way to use the old with the new. MTH didn’t have an electrial diagram to their transformers.
He can add external “sound activation buttons” to generate the bell signal as well as to add horn/whistle to the center taps on the ZW that don’t have horn/whistle controls. Part number for the button is:
610-5906-001
Wiring diagrams are provided in several of the on-line manuals, e.g. 71-9859-250.pdf
While this document is specific to a Railsounds accessory car, the button and wiring can be used for any device normally activated by horn/whistle and/or bell buttons.
The whistle control adds a DC component to the AC voltage. The whistle relays don’t care about the polarity and will blow the whistle either way; but all the old transformers make the center rail positive relative to the outside rails (if connected properly). The new locomotives respond to a positive center rail by blowing the whistle and to a negative center rail by ringing the bell.
The old transformers apply a strong DC component as the control is moved, then drop to a weaker component as it reaches the end of its travel. The strong DC is intended to first operate the relay, the weak DC to keep it operated.
Rob
Thanks Guys, my curiosity is satified. Now I need to link the answer to him. So far my approach to trains has been traditional. The biggest drawback with the electronics is knowing what is compatible.I must say the Lionel site has a been a wealth of information. I recently picked up an early chug sound tender. I found all the information I needed at the site. With some AC power and a 220 ohm resistor I got it to work! Trains are fun.