Note 3 - Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Product Warranty Liability [Table Text Block]

	December 31,
	2019			2018
Balance, beginning of the period	$	153,723		$	40,000
Provision for product warranty		-			142,000
Product warranty expirations		(141,235	)		-
Product warranty costs paid		(12,488	)		(28,277	)
Balance, end of the period	$	-		$	153,723

Research and Development Expense [Table Text Block]

	Year ended December 31,
	2019		2018
Salaries	$	60,466	$	74,694
Other costs		17,038		69,528
	$	77,504	$	144,222