Variable siren for alarm (CB9086E)

Found in a 1980’s documentation, this circuit must have its signal applied to an amplifier stage. The unijunction transistors can be 2N2646.

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Volume limiter (CB25287E)
This circuit for audio signals was found in the March 1990 Radio Electronics magazine. The circuit...
Sinusoidal Oscillator 4093 (CB21123E)
In the figure we have the way to implement a sinusoidal oscillator with the 4093 IC. The component...
Complementary Transistors Monostable (CB19362E)
Equivalent transistors, like the BC548 and BC558 pair can be used in this circuit that we find in an...