This circuit was found in a British documentation from 1969. It can be implemented with modern transistors. The pass band is 6 MHz.
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...