The operational amplifier for this tone control found in a 1977 Signetics manual may be the 741. The power supply must be symmetrical and the signal cables short. The bass gain is 20 dB.
Found in an old Elektor, this circuit uses two 7-segment displays to indicate the volume of an...
This resistance meter has a linear scale, converting resistances to voltage. The operational...
I got this circuit from an English magazine from 1977. It can still be easily assembled, as the...