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.
In the figure we have a circuit in which two moving bar/dot indicators are connected together to...
This simple unregulated half-wave font was found in old American documentation. The diode is...
This simple radio for listening to a headphone with two CK722 transistors was found in Radio...