This circuit was found in a documentation of the 80s, having didactic purpose. For R1 values between 10k to 1M can be used. Transistors are general purpose types.
We found this circuit in a 1986 documentation. It causes 40 LEDs to flash sequentially. The big...
Found in a National Semiconductor manual from the 90's, this circuit uses components of the time,...
Simple timers can be designed using inverters or any other gate that can be connected as inverter. Figure...