Found in a documentation from the 90's, this circuit uses only one integrated circuit. The resistors in series with the LEDs depend on the power that can be between 5 and 12 V.
We found this circuit in the October 1980 issue of Radio Electronics magazine. The circuit uses...
Found in an English publication from the 1980s, this circuit uses components that are still common...
With two cascading tunnel diodes, this circuit found in a 196 General Electric documentation...