This circuit was found in an English documentation from the 90s. It uses a PLL CMOS 4046 and is powered by a 9 V battery. The sensors are two electrodes that must be held by the person.
These integrated ones consist of class B amplifiers with gain fixed 24 internally for better...
Found in a 1967 publication by General Electric, this control is intended for motors up to 2 A...
Found in RCA documentation from the 90s, this bass and treble control uses an operational...