Equivalent operational amplifiers can be used on this crystal-controlled oscillator. The circuit is from old documentation and can be changed to operate on other frequencies.
The correct connection of speakers and tweeters in a speaker to obtain better sound quality,...
This circuit with germanium transistors was found in a Mullard manual from 1960. The components depend...
This circuit was found in a Popular Electronics from the 90s. The components admit equivalents and the...