Charging of capacitors with double switch. The principle of operation of auto-zero and chopper-stabilized DC amplifiers

Abstract

The problem given to the 10 Experimental Physics Olympiad (EPO10) 7 December 2023, Skopje, 11:00-15:00. The Olympiad is organized by Society of Physicists Macedonia and the Sofia Branch of the Union of Physicists in Bulgaria. The experimental set-up illustrates the principle of chopper stabilized DC amplifiers described in the patent by Edwin Goldberg and Jules Lehmann, Stabilized direct current amplifier, U.S. Patent 2,684,999 (1949). Now this principle is implemented in many contemporary operational amplifiers. In such a way this student problem is related to the operation of widely used technical device and many participants successfully solved the problem.

Updated problem and solution for EPO10, 7 Dec 2023, Skopje, N. Macedonia; 14 pages, 14 figs, 4 tables, 24 refs (including all former EPO problems and related educational and scientific articles); scanned solution of EPO10 absolute champion uploaded as a separate file named "EPO10_Abs-Champ.pdf"