Note 11 - Concentrations - Sales to Customers (Details) - USD ($)	6 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Jun. 30, 2017
Net revenues	$ 6,013,000	$ 9,672,000	$ 14,525,000
Geographic Concentration Risk [Member] | UNITED STATES
Net revenues	1,970,000	4,854,000	6,675,000
Geographic Concentration Risk [Member] | Asia - Other [Member]
Net revenues	983,000	1,717,000	1,951,000
Geographic Concentration Risk [Member] | Europe [Member]
Net revenues	721,000	1,165,000	1,739,000
Geographic Concentration Risk [Member] | CHINA
Net revenues	2,176,000	1,143,000	3,296,000
Geographic Concentration Risk [Member] | All Other Countries [Member]
Net revenues	$ 163,000	$ 793,000	$ 864,000