Entering MIL-HDBK-217 Variable Resistors
The following table describes the part parameters required for variable resistors when a MIL-HDBK-217 model is selected for the calculation. MIL-HDBK-217 models support all but the following subcategories of variable resistors:
Glass Glazed, Var
Organic Solid, Var
Parameter
Type
Description
Quality Level
Choice List
The quality screening level used in the manufacturing of the device. Choices are:
Mil-Spec
Commercial
Rheostat
Checkbox [FN1 only]
When cleared, a potentiometer connects the device in the circuit. When selected, a rheostat connects the device in the circuit. The parameters that are made available depend on whether this checkbox is selected. For example, power parameters are made available for potentiometers, and current parameters are made available for rheostats.
[Power Parameters}
Real (Watts)
For more information, see Power Parameters.
[Voltage Parameters}
Real (Voltage) [FN1 only]
For more information, see Voltage Parameters.
[Current Parameters}
Real (Watts) [FN1 only]
For more information, see Current Parameters.
Resistance
Real [FN1 only]
The resistance value of the device. This parameter is used in conjunction with Units to enter the resistance units.
Units
Choice List [FN1 only]
The units for the Resistance value. Choices are:
ohm
Kohm (ohm * 1000)
Mohm (ohm * 1E6)
Load Resistance
Real [FN1 only]
Required for Potentiometers only.
The total resistance between the wiper arm and one end of the potentiometer. This parameter is used in conjunction with Load Units to enter the load resistance units.
Load Units
Choice List [FN1 only]
Required for Potentiometers only.
The units for the Load Resistance value. Choices are:
ohm
Kohm (ohm * 1000)
Mohm (ohm * 1E6)
Number of Sections
Integer [FN1 only]
The number of sections on the device. This value is used in the actual power stress ratio calculations.
Section Used
Integer [FN1 only]
The section of the potentiometer that is used. This number cannot be greater than the value for Number of Sections. This value is used in the power stress calculations.
Number of Taps
Integer [FN1 only]
The number of potentiometer connections, including the wiper and end terminations.
Construction Type
Choice List [FN1 only]
Required only for the Power, Var WW (RP) subcategory of variable resistors.
The construction class of the device. Choices are:
Enclosed
Unenclosed
The construction class can be determined from the resistor style number. For more information, see MIL-HDBK-217.
Style
Choice List [FN1 only]
Required only for the following subcategories of variable resistors: Lead Screw, Var WW (RT, RTR); Precision, Var WW (RR); and Trimmer, Var NonWW (RJ, RJR).
The MIL-R style number of the device.
[Temperature Parameters}
Real (Degrees C)
For more information, see Basic Temperature Parameters.
[Derating Parameters]
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For more information, see Derating Parameters.