In fact, this 1967 Electronic Design circuit generates two symmetrical ramps whose frequency depends on the values of the components used. Modern equivalent transistors can be used.
This buzzer with the 555 was suggested by a Popular Electronics from the 90s to be used as a...
This is the receiver for the previous circuit found in the November 1991 Radio Electronics...
In the figure we have the configuration of series regulator protector suggested by Motorola in 1968...