Self-Balancing System for Medical and Physiological Instrumentation

There is a need in medical and physiological instrumentation for a system that can automatically correct baseline shifts. Some cases where this need arises are discussed. A self-balancing system that can be used as a general-purpose unit has been developed and is described. It consists of a binary counter, a digital to analog converter, and logic circuits. The described system automatically balances dc shifts in signals with a range of 6 V. Balancing time is less than 15 ms. The system is designed to work with tape or chart recorders with input range of ± 1 to ± 3 V. Some design parameters of this system are discussed briefly.