level indicator - or cassette interface

. . . . for cassette interface Compact cassettes, because of their low cost and easy availability, have been the mainstay memory in per- sonal and hobby computers for almost as long as these have been available. These cassettes convert digital computer data into audio signals and vice versa. They can, however, not prevent drop-outs caused by wrongly set signal levels. The present level indicator can help to prevent these mishaps. All that"s needed to build the in- dicator is a 3.5 mm jack plug, two LEDs, a resistor, small loudspeaker, and a jack socket. The LEDs are connected in anti-parallel. The loudspeaker serves as a monitor to indicate whether the recorder is emit- ting signals (audible as two quite distinct tones), or whether the cassette content is between two pro- grammes (when only a slight hiss is heard). The indicator is connected to the ear-piece socket on the recorder by the jack plug and the cassette interface input via the coaxial socket. Most cassette interfaces ne...