This circuit provides an excellent opportunity to upgrade your Märklin model train system from ‘traditional AC’ to digital control.Beginning model train enthusiasts may have more digital-ready (Märklin) locomotives moving about on the track than they are aware of. Usually, these locomotives are simply powered by the speed regulator on the main transformer. These days, model locomotives with an internal digital decoder are hardly more expensive than traditional types. That is not surprising because electronic circuits are easier and cheaper to produce in large volumes than any of the traditional reversing relays. Märklin always continued to produce decoders capable of working in ‘AC’ mode as well, allowing them to be used without problems with the famous Märklin transformer. Upgrading to all-digital control is then possible at a later stage. Possible, yes, but admittedly at a price because the cost of the upgrade will easily exceed that of all rolling stock.