The contact resistance measuring circuit

  
Contact resistance measuring circuit shown in FIG. It mainly consists of a constant current circuit and amplifying circuit. Operational amplifier 1C1 and form a transistor VT a
The contact resistance measuring circuit - schematic

follower, the voltage across the wind equals the nominal regulator VS1 steady voltage. Since the fixed resistance Ra, therefore, through Rs is a constant-current. Measured resistance string A, B-side, at the connection point with the measured resistance Ken, the current value is small, it can be measured by the resistance of the wind currents regarded as the same voltage, so that, A, B between the end and then only in the A, B-side test the resistance of the (proportional relationship). Electrical resistance measurements translate into voltage measurements. Op amp IC2 and its external RC element constituted an inverting amplifier, voltage A, B between amplification, magnification brother/Rz. c], Cz IC2 is required memory capacitance. Millivoltmeter connected to the output terminal of IC2. Measurement IC2 output voltage. False 102 fixed output voltage Vo, the voltage magnification K., VD1 rated stable voltage Vw, the measured resistance to foot., There/Ct VwR4Rn/R3RZ R Rz Ra V/R4 Vw figure. T, VD3-VD6,1C3 other components constituting the DC power supply, AC power when using the meter, stable 12V output voltage.




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