Microcomputer controlled integrator for Calvet‐type twin calorimeters

An improved integration method has been developed for use with Calvet‐type differential calorimeters. The new integrator is based on a voltage‐to‐frequency converter combined with a digital system interfaced to a microcomputer. The microcomputer provides programmed control of the integrator and, with little or no operator intervention, calculates the total heat effect making corrections for background and baseline drift. With this method a calorimetric precision of the order of ±0.1% has been achieved in experiments carried out at 651°C. This is about one order of magnitude of improvement over graphical methods and about a factor of 3 better than the analog integration techniques which we have used previously.