Voice activated intercom (CB7828E)

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

| Clique na imagem para ampliar |

Vehicle alarm (CB20627E)
This car alarm was obtained in a Signetics documentation from the 1980s. The circuit uses the 555...
Zero Frequency VCO (CB24870E)
The frequency of this circuit can be varied from zero. The circuit uses the CMOS 4046 and was...
fgtrTTL Binary Counter (CB13420E)
This simple binary counter triggers two LEDs according to the number of pulses applied to the...