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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6 V x 5 mA regulator (CB21537E)
This 6V regulator with FET was found in an old Electronic Design. FET and transistor admit modern...
Frequency Indicator (CB6342E) This simple circuit was found in an Exar publication from the 1970s. The circuit makes use of the 567 PLL indicating when the signals are in the indicated frequency range. a hre
Frequency Indicator (CB6342E) This simple circuit was found in an Exar publication from the 1970s....
External Trigger Monostable 4001 (CB16311E)
The circuit shown in the figure differs from the previous one (CIR8909) in that it can be...