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BALANCE SHEETS [Parenthetical] - USD ($)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Allowance for doubtful accounts (in dollars) $ 15,000 $ 15,000
Common stock, shares authorized 15,000,000 15,000,000
Common stock, shares issued 4,277,731 4,185,839
Common stock, shares outstanding 4,277,731 4,185,839
Convertible Preferred Stock Series B [Member]    
Convertible preferred stock, series B, cumulative percentage of interest 10.00% 10.00%
Convertible preferred stock, stated value (in dollars per share) $ 10 $ 10
Convertible preferred stock, optional redemption 103.00% 103.00%
Convertible preferred stock, optional shareholder conversion 2:1 2:1
Convertible preferred stock, shares issued 24,152 24,152
Convertible preferred stock, shares outstanding 24,152 24,152