This series LED circuit was found in the February 1992 issue of Radio Electronics magazine. The effect's speed is dependent on C1 and adjusted by R3.
This circuit from Popular Electronics powers a small speaker. The transistor can be of general use...
When the sensor X1 is opened, the relay is energized. When waiting, the current drained is very...
This circuit for measuring bridges was found in the October 1995 issue of Electronics Now...