Long Time Comparator

This circuit is a series of long-time comparator. As a comparator to use IC LM106. Long-time comparator circuit uses 2N4393 JFET is operated as a Miller integrator. The high Yfs 2N4393 (more than 12,000 mmhos @ 5 mA) produced a profit of about 60 stages. Because the gate capacitance is equivalent to look to the time the C gain and resistance sources can be as high as 10 MOhm gate, the time constant for one minute can be achieved. Here is a schematic drawing:

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