Switched tone control

Most readers will be acquainted with a tone control as found on many audio amplifiers. Such a control normally consists of a potentiometer. The one described here uses a rotary switch and a change-over switch to select attenuation or amplifcation. For stereo applications, this requires a two-wafer, six position rotary switch and two small change-over switches (or small relays). For clarity's sake, only one of the channels is shown in the diagram.