This circuit was found in old American documentation. Transistor is general purpose and coil rated is for 1.5 MHz. Wind 50 + 50 turns of wire 28 onto ferrite rod for 1 MHz.
The simplest filter for this purpose is the one shown in the figure consisting of two coils and...
We found this automotive alarm circuit in a 90's Popular Electronics circuit. The circuit emits a...
This basic op amp filter configuration was found in July 1975 Radio Electronics magazine. The...