Evolutionary algorithms can design electronic circuits that conventional design methods cannot, because they can craft an emergent behaviour without the need for a detailed model of how the behaviours of the components affect the overall behaviour. However, the absence of such a model makes the achievement of robustness to variations in temperature, fabrication, etc., challenging. An experiment is presented showing that a robust design can be evolved without having to resort to conventional restrictive design constraints, by testing in different conditions during evolution. Surprisingly, the result tentatively suggests that even within the domain of robust digital design, evolution can explore beyond the scope of conventional methods.