This filter is current driven and has the formulas given by the two diagram options. The circuit is from an American documentation from the 90s applying to any operational amplifier.
This circuit of a 1978 American publication monitors a telephone line by triggering a relay. The...
This interesting FET-tester circuit was obtained from an old American documentation. The bipolar...
This old VHF TV booster that also serves FM was found in Radio Electronics magazine from April...