Abstract: An electronic diving apparatus detects pressure by means of a bellows transducer (12). A variable frequency oscillator (10) produces a variable frequency output in proportion to the pressure applied to the transducer (12). A local oscillator (16) produces a fixed frequency signal which is mixed with the variable frequency signal in a mixer-demodulator (14) to produce an audio depth signal. The audio depth signal is provided to up/down counters (30). A time base and synchronizer circuit (24) sequences the counters (30) for an up frequency count and a down frequency count of the audio depth signal. When the difference count exceeds a preset limit, a maximum rate of depth change circuit (34) produces an alarm signal which is transmitted through a beep timer circuit (36) to activate an audio driver and output circuit (28) which produces alarm signal at an audio disk (38). This gives a warning of too rapid of an ascent or descent by the diver.