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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Bridge Digital Amplifier (CB193E)
The circuit bellow shows how four inverters [NAND, NOR or Inverters] Kim - This could be NAND,...
Battery Voltage Monitor (CB1425E )
This circuit came out in a 1978 American publication, but can be assembled with transistors BC547 or...
Modulated siren 555 (CB9201E)
This is one of the many modulated siren versions that can be found on our website. We found it in a...