This circuit was obtained from an Auguist 1974 Everyday Electronics magazine. The circuit is still current as it can be mounted with the BF245 or MPF102 transistor. The circuit is interspersed between the signal line whose intensity is to be controlled, remembering that it is a high impedance circuit for small signals. In some cases it may be necessary to merge a 100 k resistor at the point indicated by “see text”.
