CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 959,000	$ 567,000
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	1,358,000	1,224,000
Provision (recovery) for doubtful accounts	(14,000)	25,000
Deferred taxes	201,000	29,000
Foreign currency transaction (gains) losses	29,000	(113,000)
Share-based compensation	493,000	484,000
Unrealized loss on available-for-sale equity security	5,000	37,000
Changes in operating assets and liabilities:
Accounts receivable	320,000	(2,034,000)
Inventories	(1,881,000)	(821,000)
Other assets	648,000	(363,000)
Accounts payable	(865,000)	2,088,000
Advance customer payments	186,000	321,000
Accrued expenses	(561,000)	556,000
Operating lease assets and liabilities	397,000	0
Net cash provided by operating activities	1,275,000	2,000,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from maturities of available-for-sale marketable securities	2,860,000	3,969,000
Proceeds from sales of available-for-sale marketable securities	0	70,000
Purchases of available-for-sale marketable securities	(2,758,000)	(4,479,000)
Additions to equipment and leasehold improvements	(957,000)	(642,000)
Additions to patents	(61,000)	(36,000)
Net cash used in investing activities	(916,000)	(1,118,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options	59,000	251,000
Net cash provided by financing activities	59,000	251,000
Effects of exchange rate changes on cash and cash equivalents	(2,000)	9,000
Net increase in cash and cash equivalents	416,000	1,142,000
Cash and cash equivalents – beginning of period	9,248,000	6,944,000
Cash and cash equivalents – end of period	$ 9,664,000	$ 8,086,000