This circuit is from an August 1984 Radio Electronics magazine. It monitors the state of a RAM backup battery. Resistor R1 determines the battery charge.
We found this circuit in 1969 American documentation. FETs admit equivalents, as do transistors. The...
Found in a Popular Electronics from 1992, this circuit was created to give effects to an...
Both the field effect transistor and the integrated circuit of this 1970s circuit are no longer very...