Found in a Popular Electronics from the 80's, this circuit makes use of a time integrated to control a relay in a timed way. R2 determines the activation time.
This circuit was obtained in a 1991 Electronics Handbook. The publication no longer exists, but...
This is another possible version of a negative voltage generator using a 555 integrated circuit. The...
This circuit is from a 1965 Electronic Design. The transistors may be general purpose and the...