12. Income taxes (Under Review) (Details) - Deferred Income Tax Components - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Foreign net operating losses	$ 340,000	$ 282,000
Accrued lawsuit settlement expenses		1,262,000
Inventory reserves	1,312,000	1,063,000
Deferred revenue	25,000	56,000
Warranty reserve	95,000	100,000
Stock compensation expense	1,105,000	1,049,000
Other accrued compensation	475,000	406,000
Foreign tax and other credits	23,000	106,000
Other liabilities and reserves	191,000	312,000
Gross deferred tax assets	3,566,000	4,636,000
Valuation allowance	(340,000)	(340,000)
Net deferred tax assets	3,226,000	4,354,000
Deferred tax liabilities:
Depreciation	45,000	142,000
Other	36,000	76,000
Net deferred tax liabilities	81,000	218,000
Total net deferred tax assets	$ 3,145,000	$ 4,136,000