You could just get th Atlas signal attachment cable and cut the end off of it, but here's another option: http://www.azatrax.com/signal-connector-atlas-models.html
The pics on Atlas are too small to see the connector. Can you post a picture? My guess is they didn't invent their own connector but are using an off the shelf connector.
Henry
COB Potomac & Northern
Shenandoah Valley
So as the subject line says I have a question about the connectors for the HO scale Atlas signals. At the bottom of the signal there is a connector with 4 wires in it which (as I understand from what I read) connects to another cable going to the controller board. And Atlas offers a pigtail to allow a person to connect other manufacturer's signals to the cable going to the controller board. But what about going the other way? Does anyone offer a connector which mates with the Atlas plug and has 4 wires coming off to hook to another system? I plan to use the Atlas signals with a PLC and would prefer to not chop off the connector on all of the signals. I mean, I may want or need to change them in the future so why make it harder on myself? Any help anyone has on this will be greatly appreciated, as I am getting ready to start testing resistors to try and get all 3 colors about the same intensity and finding a usable pigtail would make this job a lot easier!
Good Luck, Morpar