This tone control was obtained in a Signetics documentation of the 90s. The integrated circuit can be practically any operational amplifier. The power supply is symmetrical.
Only incandescent lamp can be used in this circuit. The SCR must be mounted on a heatsink and...
This circuit originally appeared in a publication of 1997. With the changes, the circuit can be...
This circuit is from a 1969 Electronics World. The transistors may be modern general-purpose...