Grand Idea Studio

Red Box Detection

 

The Red Box is a toll fraud device commonly used to trick payphones into thinking coins have been deposited. This paper describes a circuit created to detect Red Box tones (1700Hz and 2200Hz). The detection flag, a 5V logic level signal, can be used to control external circuitry.

Paper: Red Box Detection Circuit

Published in 2600 Magazine, 14(1):54-57, Spring, 1997.

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