Practice code oscillator (CB21696E)

In the figure we have an astable multivibrator driving a speaker to produce audio signals for Morse code practice.

Ramp Generator (CB1434E )
This circuit was obtained in a 1973s documentation. The transistors may be BC558 for the PNP and...
Differential temperature alarm (CB26159E)
The sensors in this circuit that triggers when the temperature goes out of a certain range are...
MC34071 Active Band Pass Filter (CB15282E)
Other operational amplifiers series, such as MC34072, MC34074, MC35071, MC35072, MC35074 d MC33071...