This sequential circuit of LEDs was found in a Popular Electronics from the 90s. The circuit can be programmed and an adaptation consists of using optical couplers to drive power loads.
This signal follower, from a publication from the 1970s, uses old germanium transistors such as...
Although it is a common configuration today, this circuit was taken from an old publication. The...
This circuit for the 85 to 95 MHz band has a gain of 15 dB. We find it in a 1980s documentation. The...