The main feature of this circuit found in an old American publication is that it is powered by the very signal it converts. The transistors are of the time and can be replaced by current types.
This circuit can be used as a source of signals for generators of different types, sirens, or...
This circuit is based on a 5 V LED flasher. We found it in October 1980 Radio Electronics...
This interesting circuit in which the LED display is circular imitating a common clock appeared in the...