Adjustable hysteresis (CB21515E)

This circuit was suggested by a 1967 Electronic Design. Modern equivalent transistors can be used.

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Morse 555 Oscillator (CB26325E)
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Audio generator 741 (CB8650E)
In the figure we have the circuit of a complete audio generator using the 741. The circuit was found...
Timing circuit 4046 (CB24997E)
This monostable multivibrator with signals in phase opposition was found in October 1986 Radio...