Indicated for discriminators adjustment in FM and VHF receivers, this circuit was found in a 90s 73 magazine for radio amateurs. The operational amplifier can be a general-purpose type.
Two operational amplifiers are used in this source obtained in an American documentation...
This circuit is suggested by the Linear Applications Handbook of National Semiconductor, being used...
This simple circuit for headphones or small speakers was found in documentation from the 90s. The...