I upgraded my BR53 Mallet (#3102) to digital with a 5* motor and Mld decoder.
Installed one smoke unit (#7226) connected to Aux2 on the decoder, works fine,although it would be nice to see some heavier smoking (any idea how to get that?)
The question however is: can I drop in the second smoke unit connected to the same Aux2 without blowing up the decoder? I have only one wire going from the decoder to the stacks....

Regards
Jean-Pierre

The decoder overload protection will probably kick in, if you try to use two 7226 on the same aux.

In my 3502 I wired up one wire for each smoke generator. I just bent down one of the contact lips and isolated it, then I soldered in an extra wire to the 2nd smoke generator.

note that when you are using a relay, it will give the smoke generator a full track voltage of 19v or more... But if you use an optical relay you can reduce that voltage with the aux dimming function.
eg in my Big Boy, I installed a TLP3122 optical relay on aux1 (and a resistor and fuse). And adjusted the "track" voltage down to approximately 16v for the 2x7226 smoke generators.
Running it at a higher voltage might give more smoke and might shorten its life so it's at your own risk. The smaller optical relay will fit more easily in the br 53 tender.
Märklin has also used this type of relay in some locomotives, more infor here:
https://moba-hgh.de/modellbahn/tipps-tricks-infos/1718-tuning-der-rauchsatzansteuerung-jetzt-raucht-s-richtig