Warranty (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Warranty
Period of warranties, low end of the range	90 days
Period of warranties, high end of the range	1 year
Warranty provisions and claims for the years
Balance at Beginning of Year	$ 205,506	$ 217,819	$ 209,710
Acquired provision - Dansensor	85,413
Warranty Provisions	374,758	227,112	305,167
Warranty Claims	425,056	239,425	297,058
Balance at End of Year	$ 240,621	$ 205,506	$ 217,819