Note A - Summary of Significant Accounting Policies (Tables)
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12 Months Ended |
Sep. 30, 2018 |
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| Notes Tables |
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| Investments Classified by Contractual Maturity Date [Table Text Block] |
| | | September 30, 2018 | | September 30, 2017 | | Less than one year | | $ | 8,930,225 | | | $ | 5,937,150 | | | 1-5 years | | | 17,974,000 | | | | 19,816,000 | | | Total | | $ | 26,904,225 | | | $ | 25,753,150 | | |
| Allowance for Credit Losses on Financing Receivables [Table Text Block] |
| Year Ended | | | Balance at Beginning of Year | | | | Additions Charged to Costs and Expenses | | | | Less Write-offs | | | | Balance at End of Year | | | September 30, 2018 | | $ | 79,085 | | | $ | - | | | $ | - | | | $ | 79,085 | | | September 30, 2017 | | | 93,473 | | | | - | | | | (14,388 | ) | | | 79,085 | | | September 30, 2016 | | | 79,473 | | | | 25,000 | | | | (11,000 | ) | | | 93,473 | | |
| Schedule of Inventory, Current [Table Text Block] |
| | | | September 30, 2018 | | | | September 30, 2017 | | | Raw materials | | $ | 6,013,166 | | | $ | 5,991,863 | | | Work-in-process | | | 560,988 | | | | 724,248 | | | Finished goods | | | 3,475,981 | | | | 1,737,456 | | | Inventories, net | | $ | 10,050,135 | | | $ | 8,453,567 | | |
| Property, Plant and Equipment [Table Text Block] |
| | | | September 30, 2018 | | | | September 30, 2017 | | | Manufacturing equipment | | $ | 5,202,532 | | | $ | 5,370,962 | | | Office equipment | | | 3,809,614 | | | | 3,600,006 | | | Leasehold improvements | | | 2,417,786 | | | | 2,404,331 | | | Vehicles | | | 226,221 | | | | 193,702 | | | Property, plant and equipment, gross | | | 11,656,153 | | | | 11,569,001 | | | Less accumulated depreciation | | | 6,911,569 | | | | 6,134,829 | | | Property, plant and equipment, net | | $ | 4,744,584 | | | $ | 5,434,172 | | |
| Schedule of Finite-Lived Intangible Assets [Table Text Block] |
| | | September 30, 2018 | | | | | Years | | | | Gross Carrying Amount | | | | Accumulated Amortization | | | | Net Book Value Amount | | | Customer relationships | | | 15 | | | $ | 3,742,000 | | | $ | 155,917 | | | $ | 3,586,083 | | | Certifications | | | 8 | | | | 1,068,000 | | | | 83,437 | | | | 984,563 | | | Trademarks | | | 8 | | | | 563,000 | | | | 43,984 | | | | 519,016 | | | Patents | | | 20 | | | | 393,002 | | | | 24,981 | | | | 368,021 | | | Other | | | 5 | | | | 31,091 | | | | 6,219 | | | | 24,872 | | | Totals | | | | | | $ | 5,797,093 | | | $ | 314,538 | | | $ | 5,482,555 | | | | | September 30, 2017 | | | | | Years | | | | Gross Carrying Amount | | | | Accumulated Amortization | | | | Net Book Value Amount | | | Patents | | | 20 | | | $ | 269,433 | | | $ | 15,737 | | | $ | 253,696 | | | Other | | | 5 | | | | 31,091 | | | | - | | | | 31,091 | | | Totals | | | | | | $ | 300,524 | | | $ | 15,737 | | | $ | 284,787 | | |
| Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] |
| | Year ending September 30 | | | | Amount | | | | 2019 | | | $ | 471,215 | | | | 2020 | | | | 471,215 | | | | 2021 | | | | 471,215 | | | | 2022 | | | | 471,215 | | | | 2023 | | | | 464,997 | | | | Thereafter | | | | 3,132,698 | | | | Total future amortization expense | | | $ | 5,482,555 | | |
| Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] |
| Year ended September 30, | | 2018 | | 2017 | | 2016 | | Net income | | $ | 4,274,547 | | | $ | 3,847,839 | | | $ | 8,013,062 | | | Weighted average common shares | | | 13,429,232 | | | | 13,532,375 | | | | 13,372,579 | | | Dilutive potential common shares | | | 23,628 | | | | 128,431 | | | | 290,770 | | | Weighted average dilutive common shares outstanding | | | 13,452,860 | | | | 13,660,806 | | | | 13,663,349 | | | Earnings per share: | | | | | | | | | | | | | | Basic | | $ | 0.32 | | | $ | 0.28 | | | $ | 0.60 | | | Diluted | | $ | 0.32 | | | $ | 0.28 | | | $ | 0.59 | | |
| Useful Lives [Member] |
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| Notes Tables |
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| Property, Plant and Equipment [Table Text Block] |
| | | Years | | Equipment | | | 3 | - | 7 | | Leasehold improvements | | | 7 | - | 10 or life of lease | | Vehicles | | | | 3 | | |