Detonators are widely used in explosive applications, with commercial systems being mass produced from a number of suppliers. One issue that affects producers and users is the reproducibility and output of the explosive system. This can be considered from both the component parts and as the fully assembled detonator. This paper outlines a simple experimental system for measuring the output of detonators or small amounts of explosive. The basis of the technique was pioneered by Bertram Hopkinson in the early 20th Century, here the fundamental idea is applied with advanced instrumentation to both calibrate the system and show its potential for use in both fundamental and applied research.