ive got the the green 30th anniv version-made in germany
these are great locos imho
simple, diminutive
noisier slightly than a stainz
reasonably weighted too
i fitted mine with an 18v smoker
and as i recall
the loco actually has prongs for the purpose of plugging in the smoker
all i recall is that it was easy and there was some sort of factory provision on the little board (its been several years since i did it)
heres my 2 cents
dont bother
why?
(i love smoke in my locos btw)
the otto runs very efficiently, ie, like a bat out of hell on not very much voltage
so to get enough voltage for the loco to smoke
you are running not merely a a good clip, but one that challenges continued adhesion on the curves!
give it a go, if you like
i havent bothered to remove my smoker from my otto,
but i can tell you, knowing what i do now, i wouldnt have popped for the 15-20 dollars for the unit, given the above
this coming from a guy that is absolutely OK with my stainzs and 2015s running fast enough to smoke profusely (15-20v!!) (on R3s of course)
otto wil lbe a bit quieter btw, if you lightly grease with a plastic compatible teflon grease-dont know what it is about teflon, but it seems to do more in this regard than the LGB grease
the alternative would be to do a step down in voltage and use a 5 v