Found in a 1968 US publication, this circuit produces a delayed pulse with the negative transition of the input signal. The circuit can be used as a shield.
This circuit is from a 1982 documentation. Here we have an adaptation of the circuit already...
This battery charger was found in a Popular Electronics from the 1980s. Voltage regulators must be equipped...
The frequency of the blinking of this circuit is given by the capacitor that can have its value...