Found in a 90s EDN, this circuit is indicated for power control through a 4-20 mA line. The circuit makes use of optical couplers of the time.
This circuit was obtained in a 1978 English magazine. This adjustable stabilized power source...
This circuit was found in old documentation, but as it uses the 555 it can still be easily...
This timer with field effect transistors was obtained from Fairchild documentation. The times...