Digitization of old DUO-Locos (21900)

On several occasions, we set up a circuit here to digitize the old DUO locomotives with electric decouplers.
The circuit was tested by me once on an XL decoder and worked and is in this form only for one drive usable.
Nevertheless, I can give no guarantees for replicas, this is at your own risk.
The circuit must be doubled for both drives.
The function output of the decoder is programmed to full voltage (not dimmed).
The roof flash light function must be implemented via 2 additional F outputs.