Circuit Diagram of Audio Logic Level Probe Composed of 555

Published:2011/7/2 22:11:00 Author:Vicky | Keyword: Audio Logic Level Probe | From:SeekIC

The above picture is audio logic level probe circuit, which is composed of voltage comparator, multivibrator, and piezoelectric ceramics HTD etc. The latter two constitute audio circuit and the audio frequency is used to assess the TTL or COMOS instrument’s electrical level. When the probe reaches high level, IC-1 sends out signal to make D2 conducted and charge C1 via R9 and R11. The oscillator works, and the correspondent oscillating frequency is fH=1.44/(R10+2R11)C1, the correspondent frequency of the parameter in the picture is abouth 4kHz. When the probe reaches low level, the matched D3 is conducted, and C1 is charged via R10 and R11. The correspondent oscillator circuit works with oscillating frequency of fL=1.44/(R10+2R11)C, and the correspondent frequency of the parameter in the picture is about 700Hz. When pulse train is detected, the correspondent HTD sends out mixed sound or trill sound.



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