Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating activities
Net loss	$ (1,494)	$ (1,565)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Inventories allowances	72	49
Deferred tax expense (benefit)	28	(164)
Depreciation and amortization	661	575
Share-based compensation expense-stock options	60	68
Share-based compensation expense-restricted stock units	89	74
Loss (gain) on investment in securities	506	(444)
Changes in operating assets and liabilities:
Trade accounts receivable	381	628
Inventories	3,914	(1,840)
Prepaid expenses and other current assets	325	269
Other assets	54	(4)
Lease liability	44	0
Accounts payable	(838)	1,246
Accrued compensation and related taxes	(331)	(691)
Accrued warranty expense	(337)	(106)
Deferred revenue	557	417
Accrued other expenses and other current liabilities	(94)	155
Net cash provided by (used in) operating activities	3,597	(1,333)
Investing activities
Purchases of property, plant and equipment	(525)	(1,462)
Net cash used in investing activities	(525)	(1,462)
Financing activities
Proceeds from issuance of common stock	0	2
Cash dividends declared and paid	(502)	(510)
Repurchase of common stock	(269)	(550)
Proceeds from debt	2,196	0
Repayment of debt	(2,234)	0
Net cash used in financing activities	(809)	(1,058)
Net change in cash and cash equivalents	2,263	(3,853)
Cash and cash equivalents, beginning of period	4,676	11,268
Cash and cash equivalents, end of period	6,939	7,415
Supplemental disclosure
Cash paid for interest	$ 11	$ 0
Non-cash financing activity
Common stock issued under restricted stock units	56	140