The Hex Frog Juicer will work fine with O scale locomotives. The Hex Frog Juicer only provides power to one wheelset at a time when crossing frogs. DCC-equipped O scale locomotives draw 2+ amps only when the wheels are slipping.
It might not be a good idea to use the Hex Frog Juicer as an auto-reverse if you run a consist over the reversing section with several locomotives on the track section at once.
