Voice activated intercom (CB7828E)

This one-channel circuit was found in a 90s Popular Electronics, functioning as a vox. Components are common today.

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3-bit AD Converter (CB4913E)
This fast circuit was found in an ancient American documentation. Output conversion speed is 30 ns and...
High Pass Filter for High Frequencies (CB12576E)
The filter shown in the figure can operate with frequencies up to several tens of megahertz thanks...
4 W amplifier TDA1013B (CB15982E)
This audio amplifier has an internal DC volume control with logarithmic characteristics and a...