Figure; Calibrating 1:10 Divider; Applications - Keithley 2182 User Manual

5-18 Ratio and Delta

Applications

Calibrating resistor network dividers
Ratio can be used to calibrate resistor network dividers. The 1:10 divider network in

Figure 5-5

of the parallel combination of the 2kΩ pot and the 2kΩ resistor. The pot provides fine tuning of
the network.
Figure 5-5

Calibrating 1:10 divider

2182
CH 1
CH 2
The Keithley Model 220 is used to source a constant current of 1mA. Channel 1, which is
used to measure the 1kΩ resistance component of the network, should be set to the 1V range
(1kΩ × 1mA = 1V) or autorange. Channel 2, which is used to measure the 10kΩ resistance
component, should be set to the 10V range (or autorange).
When Ratio is enabled, the Model 2182 will display the result of V1 (≈1V) divided by V2
(≈10V):
Ratio =
The network can then be calibrated by adjusting the network pot until a reading of 0.10000
is displayed.
is made up of nominal resistances of 1kΩ and 10kΩ. The 1kΩ resistance is the result
HI
2kΩ
Pot
DCV1
LO
HI
DCV2
LO
Filt V1 ≈1V
= = ≈0.1
≈10V
Filt V2
The above calculation includes Channel 1 Filter. If Filter is not
used, remove the "Filt" component from the calculation.
1mA
2kΩ
Model 220
Current Source
10kΩ