Today we have more compact solutions. This is from a Radio Electronics magazine from October 1990. It uses the technology of the time.
This general-purpose two-transistor circuit was found in the November 1993 issue of Electronics Now. The...
This circuit with integrated TTL 7400 has a good teaching purpose, drawing one of two LEDs. The...
This circuit is from 2002 documentation, requiring a symmetrical source of 6 to 12 V. The signal...