Found in a 1967 EEE, this circuit uses the signal from the alternating current power grid to produce pulses from a Unijunction. The circuit is directly excited by the mains voltage.
This circuit is from a 1979 publication. The sensor consists of plates or screens that, when...
The circuit is from a Radio Electronics from August 1989. The cells used at that time did not have...
The automatic modulated siren circuit shown in the figure really produces an interesting sound...