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LM393: LM393 comparator usage in the resistance meter range control

Part Number: LM393

LM393 is to me familiar from 1970 -1985 when I was a designing Nokia Capacitor Factory devices. 

It was then only DIP8 device, now I use SO8 devices, but the operation is same.

This design needs  a positive feedback, so that I got very sharp range change.

Without positive feedback LM393 was not working properly just when the both inputs ( + and -) were almost similar.

The meter needs automatic star and  automatic range control, but it used very old AD-device ICL7106, which needed two power supply voltages,

but I have only one 3 V battery .

It need to use very little current 300uA when the device was in not working.

It used about 10mA when everything was working.

I have designed these kinds of the devices already many years, but now I have no oscilloscope available.

It was broken,

Here are my memories ( add : )

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Pekka Ritamaki