fixed current造句

Can batteries produce any current they want, and cells can only produce a fixed current?
Likewise, due to limitations on permittivity, stable suspension or levitation cannot be achieved in a static magnetic field with a system of permanent magnets or fixed current electromagnets.
The standard traditional neon transformer, a magnetic shunt transformer, is a special non-linear type designed to keep the voltage across the tube raised to whatever level is necessary to produce the fixed current needed.
It's difficult to find fixed current in a sentence. 用fixed current造句挺难的