Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating activities
Net loss	$ (1,192)	$ (1,318)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Inventories allowances	38	19
Deferred tax benefit	0	(355)
Depreciation and amortization	320	256
Share-based compensation expense	30	31
Restricted stock unit compensation expense	21	41
(Gain) loss on investment in securities	306	(592)
Changes in operating assets and liabilities:
Trade accounts receivable	(626)	676
Inventories	2,538	(715)
Prepaid expenses and other current assets	(69)	(143)
Other assets	28	1
Lease liability	23	0
Accounts payable	(474)	602
Accrued compensation and related taxes	(226)	(951)
Accrued warranty expense	(149)	(88)
Deferred revenue	424	296
Accrued other expenses and other current liabilities	(77)	(68)
Net cash provided by (used in) operating activities	915	(2,308)
Investing activities
Purchases of property, plant and equipment	(131)	(829)
Net cash used in investing activities	(131)	(829)
Financing activities
Cash dividends paid	(252)	(256)
Repurchase of common stock	(243)	(337)
Proceeds from issuance of common stock	0	2
Repayment of debt	(19)	0
Net cash used in financing activities	(514)	(591)
Net change in cash and cash equivalents	270	(3,728)
Cash and cash equivalents, beginning of period	4,676	11,268
Cash and cash equivalents, end of period	4,946	7,540
Supplemental disclosure
Cash paid for interest	$ 5	$ 0