Tone-controlled microphone amplifier (CB20806E)

This circuit was found in American documentation from the 1980s. The integrated circuit used is still common today, but equivalents can be used.

| Clique na imagem para ampliar |

2-Tone Siren (CB18189E)
Because it uses TTL integrated circuits, this siren must be powered by 5 V or as indicated with D1 to...
Speaker Circuits (CB16349E)
The correct connection of speakers and tweeters in a speaker to obtain better sound quality,...
Schmitt trigger 40106 (CB21565E)
The CMOS PLL used on this circuit is not very common. The circuit can be used to take out contact...