Multifunctional conductivity test circuit

This circuit can be used to test the conductivity of conductors, test the strength of chemical electrolytes,
test the temperature, humidity, and environmental changes of conductors and insulators, test the conductive properties of transistors, test the on-off status of circuits, and test the conductivity of solutions Comparison test and capacitor leakage test
, etc. As shown in Figure 5-42.
    Circuit principle: The circuit of this multi-function tester consists of detection electrode
, resistor divider, buffer circuit and two-color diode .
The detection electrode can sense the resistance of the object being measured and
control the two-color diode to emit light according to the resistance of the object being measured. When the detection electrode senses
the resistance of the object to be measured in the range of 300n-1000kfl, the green indicator
light is on; when the resistance of the object to be sensed is less than 300krl, the red indicator
light is on, making the two-color synthesis into orange-red light; the resistance of the object to be sensed
is greater than 1000kn At this time, the two-color indicator light U and LED4 do not emit light.
Adjusting the variable resistor RP can change the sensing range of the detection electrode .