If projector is all metal, and thus crudely shielded, not much. If all plastic, other rules apply. If wire is coming out of a metal projector into a plastic region where it could be exposed to cell phone radiation or the RF hash of a night club, then run a two conductor shielded wire with shield to case ground. Only ground the shield at ONE end of the cable, leave the other floating. (Yep, I said case ground, its a dc-low frequency signal, not a differential galvo signal, Case is just fine)
Last edited by mixedgas; 04-11-2017 at 10:23.
Qui habet Christos, habet Vitam!
I should have rented the space under my name for advertising.
When I still could have...