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.
The frequency depends on the coil and is not found in the original documentation but should be...
This is a device for those who need to show that they know how to use digital electronics but have...
Using an operational amplifier with FET, this circuit from a 1977 publication can generate...