The Improved Williamson Amplifier
The "improved" Williamson Amplifier Circuit - as revised by Williamson 1949 and re-issued by GEC 1957 - is shown hereunder. Changes from the original design are minimal and relatively insignificant to performance. They include the addition of C2 and R2 to improve stability in the negative loop feedback circuit and use of an indirectly heated rectifier to limit voltage surge at switch-on. They also included construction details on a single chassis instead of a separate power supply unit.