This circuit is from a 1969 Electronics World. The transistors may be modern general-purpose equivalents. The circuit is for frequency ranges between 250 Hz and 250 kHz.
Found in Radio Electronics from the 90s, this circuit uses a 741 and can be changed to other...
The circuit is of the Motorola Linear Databook of 1990. The power source must be symmetrical and the...
This circuit was found in a 1980s documentation. The operational amplifier is of a common type at the...