Proportioning Temperature Controller
David S. Lazarus, A. W. Lawson · Review of Scientific Instruments · 1947
Unbalance voltage from a potentiometer is amplified by a simple circuit employing a 60-cycle polarized interrupter, and used to control the extent of the on-off cycle of a furnace. Automatic cold-junction compensation and a sensitive, temperature-indicating circuit are incorporated. The circuit responds to a change in input voltage of less than 4 microvolts. The long-term stability is limited by changes in 60-cycle pick-up and aging of components to about 40 microvolts.