Condensed Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities:
Net income (loss)	$ 358,878	$ (1,088,502)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization	97,990	144,380
Stock based compensation	33,798	76,204
Provision for ( recovery of) accounts receivable allowances	(185)	(2,599)
Provision for inventory reserves	0	(3,306)
Changes in operating assets and liabilities:
Accounts receivable	(606,421)	395,355
Inventories	(177,628)	249,544
Prepaid expenses and other assets	(487,067)	463,285
Accounts payable and accrued expenses	920,752	(510,857)
Net cash provided by (used in) operating activities	140,117	(276,496)
Investing activities:
Cost of other assets	(40,000)	(88,320)
Purchases of plant and equipment	(18,905)	(192)
Net cash provided by (used in) investing activities'	(58,905)	(88,512)
Financing activities:
Net funds received from (to) bank credit lines	(39,707)	238,985
Proceeds from stock option exercises	152,463	45,025
Net cash provided by (used in) financing activities	112,756	284,010
Net change in cash	193,968	(80,998)
Cash and cash equivalents at beginning of period	229,218	179,846
Cash and cash equivalents at end of period	423,186	98,848
Supplemental disclosures of cash flow information:
Cash paid during the period for: Interest	6,168	25,797
Cash paid during the period for: Income taxes	$ 3,598	$ 0