This circuit is from an 80's documentation. The circuit makes use of a component of the era, the ICL8007. The power supply should be symmetrical and the probe should be the one usually used in this type of application.
This circuit is from an 80's documentation. The circuit makes use of a component of the era, the ICL8007. The power supply should be symmetrical and the probe should be the one usually used in this type of application.