To construct a perpendicular bisector for the segment below, you will need a compass.
1. Open the compass to a distance of more than half of the segment, with one of the parts of the compass in point A. Make a trace with the compass at some distance from the segment.
2. Repeat the same procedure but in this case at point B.
3. With one rule squad you need to make a perpendicular line from the segment AB (you can also use another rule to make this perpendicular line).
4. You will have something like this:
The perpendicular is a bisector of the segment AB.