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 controls a relay causing it to open and close its contacts at a speed that depends on the...
This circuit from Ferranti was released in 1969. It makes use of the company's transistors that admit...
This photoelectric circuit was found in a 70’s Ferranti's documentation. The circuit uses an...