This circuit was found in a1980s Motorola documentation. The integrated circuit is from that time. The frequency depends on the crystal.
This circuit is indicated for measurement bridges as a null detector, thanks to the logarithmic gain...
This circuit, of a Popular Electronics of 1969 is destined to firing a gas LASER of the time. The...
This bass booster preamp is from an English publication (1966). We can mount it with more modern...