This PLL with operational amplifiers was found in 1969 documentation. The configuration can be adapted to use modern components. The circuit has a gain of 15 V / V and can operate with 10 kHz signals.
This programmable sound circuit was found in the July 1978 issue of Radio Electronics magazine. It uses an...
In the figure we have an interesting protection bridge against power polarity inversion of a...
Found in 1980s documentation, this amplifier uses a symmetric source and the gain is given by the...