This flasher was found in an 80's Electronic Engineering but can be easily implemented with modern general purpose transistors. The frequency depends on C1.
This is the basic configuration of an operational amplifier sample & hold circuit. The FET and...
The integrated circuit 4136 consists of operational amplifiers of type 741 in the same enclosure and...
We find this circuit in a 1987 publication. It makes use of comparators constructed around the 741...