Found in American documentation from the 90s, this circuit has the signal frequency determined by capacitors from C4, C3, C2 and C5 selected by digital switches.
This circuit is from a Popular Electronics from the 90s. Its gain is 22 dB and can be used as a...
This circuit was found in an article in Radio Electronics magazine from October 1962. At that...
This circuit can be implemented with other operational amplifiers. The formulas for calculating the...