Portable hypoxia monitoring circuit ICL7660 PC254A PC153A

Posted on Mar 28, 2007

As shown in FIG portable hypoxia monitoring circuit. The circuit consists of the oxygen sensor OS-12, DC amplifier IC1, A/D converter IC4, a liquid crystal display F2100-34PI,

Portable hypoxia monitoring circuit ICL7660 PC254A PC153A
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the voltage comparator IC2, the positive and negative power converter IC. And other components. OS-12 for the galvanic cell type oxygen sensor to detect oxygen in the air may be the output signal of about 50mV, and its linear output from 0 to 100% oxygen concentration range, its output - input A/D converter It can be very accurately with a digital display of the oxygen concentration. IC1 is a DC amplifier, the output signal of the sensor can be expanded up to 8 times. The amplified signal is IC4 (ICL7107 type) after A/D conversion directly driving the liquid crystal display F2100 34PI, with a digital display of oxygen concentration. ICL7107 is 3.5 chip A/D converter, and the LED display when used in combination, the current consumption can be reduced to about 1mA. It is a constant current diode D1 to A/D-converter reference voltage. CR033 is the use of a constant current characteristic of the FET element, if provided 330 mu A current temperature coefficient close to zero. Voltage comparator IC2 D1 obtained from the reference voltage, for detecting oxygen concentration of 18% or less, the oxygen concentration is low alarm. IC3 is from the positive supply to the negative supply converter itself low leakage current. Power 4 450mA of NiCd batteries can be used continuously l00h. The circuit can monitor the concentration of oxygen at the bottom of underground tunnels and caves and other workplace to prevent hypoxia accidents.

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