Employing the XR2206 IC, this circuit was found in the May 1977 issue of Radio Electronics magazine. The formula next to the diagram gives the component values as a function of frequency.
This circuit for the medium wave range was suggested by a Popular Electronics from the 90s. The...
This version of a call-fish is from 1981 using, for this reason, a 90 V battery that is no longer...
This musical doorbell was found in a Popular Electronics from the 90s. The U4 melody generator...