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 circuit converts square (rectangular) signals into triangular signals with typical 16 V...
We found this circuit in a spy book from the 90s. Transistors admit equivalents and the coil can...
This circuit was obtained in a 1979 English magazine. This circuit is a treble filter that,...