Engineer-Joe posted:gunrunnerjohn posted:In conventional mode, you'll have continuous horn or bell, depending on which way you're running. The motors are typically 12V, so you could run them on variable DC with polarity reversal for direction control.
What?
When I test a board on the bench with DC, the bell or horn doesn't play continuously that I remember.
I also run DC outside in command. I'll have to go try it without the TIU.
Well, you're right! In conventional the PS/2 actually runs polarity sensitive for direction. You don't have any control of horn or bell obviously, but at least they're not going off. I don't think I ever tried DC in conventional mode, I just assumed it wouldn't work
Score one for Joe! 
DC in command mode works fine, though for PS/2 you have to be aware of polarity on the rails. PS/3 has automatic sensing for DC and doesn't have a problem with the polarity.
