This circuit is from American documentation from the 1980s. The transistors are general purpose types and the relay can be 6 or 12 V depending on the supply voltage.
This circuit visually indicates that a high voltage is present in an outlet or other point. The...
This circuit found in a 1988 documentation consists of a timer or sequential timer controller. The...
Using a 4017 as a base, this circuit from a 1990s Popular Electronics generates low-frequency...