This type of answering machine was common at the time this circuit was published. Using two tape recorders, it was published in the June 1986 issue of Radio Electronics magazine.
This oscillator was found in the November 1986 issue of Radio Electronics magazine. The frequency...
This sophisticated circuit with a low, medium, and high treble filter is from 1990 documentation. The...
This circuit was obtained from a 1998s Popular Electronics. The magazine no longer exists, but the...