Amateur equipment is good enough. But you cannot detect it with a naked eye.
The change in flux for a passing exoplanet in transit is roughly 1%...2% at most for the larger exoplanets - and it is a gradual change. That's a change you do not notice with the naked eye, but it needs photographic equipment to create a sequence of images which allow analysis of brightness of all seen stars in order to detect the variation in the one interesting one.
With an appropriate camera and stable mount your 70mm telescope will suffice to detect these light changes in a sequence of moderately long-exposure images over the course of a few hours (exposure time a few minutes each).
Many of the professional ground-based exoplanets surveys don't use or didn't use much larger telescopes (e.g. see the HATnet programme). The difference often is more in the grade of automation, the sensitivity of the photographic equipment and automation of data processing pipeline.