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  <xsd:element name="DeferredTaxAssetsCapitalizedResearchAndDevelopmentCost" id="nssc_DeferredTaxAssetsCapitalizedResearchAndDevelopmentCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="CashCashEquivalentsAndInvestmentsPolicyPolicyTextBlock" id="nssc_CashCashEquivalentsAndInvestmentsPolicyPolicyTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="NumberOfMonthsNoticeForNonRenewalEmploymentAgreement" id="nssc_NumberOfMonthsNoticeForNonRenewalEmploymentAgreement" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" />
  <xsd:element name="NumberOfMonthsSeveranceBenefitOfSalary" id="nssc_NumberOfMonthsSeveranceBenefitOfSalary" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" />
  <xsd:element name="NumberOfMonthsSeveranceBenefitOfHealthInsurance" id="nssc_NumberOfMonthsSeveranceBenefitOfHealthInsurance" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" />
  <xsd:element name="O2024Q1DividendsMember" id="nssc_O2024Q1DividendsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="O2024Q2DividendsMember" id="nssc_O2024Q2DividendsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="O2024Q3DividendsMember" id="nssc_O2024Q3DividendsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="O2024Q4DividendsMember" id="nssc_O2024Q4DividendsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="UnrecognizedTaxBenefitsIncreaseDecreaseResultingFromStateFilingTaxPositions" id="nssc_UnrecognizedTaxBenefitsIncreaseDecreaseResultingFromStateFilingTaxPositions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="O2025Q1DividendsMember" id="nssc_O2025Q1DividendsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ShortTermTimeDepositsMember" id="nssc_ShortTermTimeDepositsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="EffectiveIncomeTaxRateReconciliationNondeductibleExpenseExecutiveCompensation" id="nssc_EffectiveIncomeTaxRateReconciliationNondeductibleExpenseExecutiveCompensation" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="EffectiveIncomeTaxRateReconciliationTaxExpenseBenefitExecutiveCompensationPercent" id="nssc_EffectiveIncomeTaxRateReconciliationTaxExpenseBenefitExecutiveCompensationPercent" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="VicePresidentOfEngineeringMember" id="nssc_VicePresidentOfEngineeringMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="LegalAndOtherContingenciesPolicyTextBlock" id="nssc_LegalAndOtherContingenciesPolicyTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="InventoryCurrentAndNoncurrent" id="nssc_InventoryCurrentAndNoncurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ShareRepurchaseProgramAuthorizedAdditionalNumberOfShares" id="nssc_ShareRepurchaseProgramAuthorizedAdditionalNumberOfShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="ShareRepurchaseProgramNumberOfSharesPurchasedAsPartOfPubliclyAnnouncedPlansOrPrograms" id="nssc_ShareRepurchaseProgramNumberOfSharesPurchasedAsPartOfPubliclyAnnouncedPlansOrPrograms" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="CashDividendsDeclaredAndNotPaid" id="nssc_CashDividendsDeclaredAndNotPaid" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="O2025Q2DividendsMember" id="nssc_O2025Q2DividendsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="O2025Q3DividendsMember" id="nssc_O2025Q3DividendsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="O2025Q4DividendsMember" id="nssc_O2025Q4DividendsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="InterestIncomeAccruedShortTermInvestmentsOtherIncreaseDecrease" id="nssc_InterestIncomeAccruedShortTermInvestmentsOtherIncreaseDecrease" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="SingleReportableSegmentMember" id="nssc_SingleReportableSegmentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="O2026Q1DividendsMember" id="nssc_O2026Q1DividendsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="O2026Q2DividendsMember" id="nssc_O2026Q2DividendsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="O2026Q3DividendsMember" id="nssc_O2026Q3DividendsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="O2026Q4DividendsMember" id="nssc_O2026Q4DividendsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ScheduleOfBalanceSheetSupplementalDisclosureRelatingToOperatingLeasesTableTextBlock" id="nssc_ScheduleOfBalanceSheetSupplementalDisclosureRelatingToOperatingLeasesTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="ShareBasedPaymentAwardOneMember" id="nssc_ShareBasedPaymentAwardOneMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ShareBasedPaymentAwardTwoMember" id="nssc_ShareBasedPaymentAwardTwoMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="NumberOfStockOptionPlans" id="nssc_NumberOfStockOptionPlans" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="TwoCustomersMember" id="nssc_TwoCustomersMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="O2027Q1DividendsMember" id="nssc_O2027Q1DividendsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="RecoveryOfImportDuties" id="nssc_RecoveryOfImportDuties" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="RecoveryOfImportDutiesPriorPeriods" id="nssc_RecoveryOfImportDutiesPriorPeriods" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="EffectiveIncomeTaxRateReconciliationForeignOperationsWithholdingTaxAmount" id="nssc_EffectiveIncomeTaxRateReconciliationForeignOperationsWithholdingTaxAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="EffectiveIncomeTaxRateReconciliationForeignOperationsWithholdingTaxPercent" id="nssc_EffectiveIncomeTaxRateReconciliationForeignOperationsWithholdingTaxPercent" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="LineOfCreditCollateralPercentageOfCommonStockOfForeignSubsidiaries" id="nssc_LineOfCreditCollateralPercentageOfCommonStockOfForeignSubsidiaries" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" />
  <xsd:element name="ThreeCustomersMember" id="nssc_ThreeCustomersMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="FounderAndExecutiveChairmanMember" id="nssc_FounderAndExecutiveChairmanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="AnnualPerformanceBonusOnBaseSalaryPercentage" id="nssc_AnnualPerformanceBonusOnBaseSalaryPercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="AnnualEquityAwardOnBaseSalaryPercentage" id="nssc_AnnualEquityAwardOnBaseSalaryPercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="ChiefExecutiveOfficerAndPresidentMember" id="nssc_ChiefExecutiveOfficerAndPresidentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="SeverancePaymentsUponTerminationMultiplier" id="nssc_SeverancePaymentsUponTerminationMultiplier" type="xbrli:pureItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="FormerChiefExecutiveOfficerMember" id="nssc_FormerChiefExecutiveOfficerMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
</xsd:schema>
