Export Sales and Major Customers (Details) (USD $)	3 Months Ended
	Aug. 31, 2012	Aug. 31, 2011
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	$ 1,965,000	$ 2,128,000
Power Transistors [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	414,000	313,000
Hybrid [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	856,000	1,101,000
Field Effect Transistors [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	155,000	205,000
Power MOSFETS [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	540,000	509,000
Europe and Australia [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	11,000	4,000
Europe and Australia [Member] | Power Transistors [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	0	0
Europe and Australia [Member] | Hybrid [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	0	1,000
Europe and Australia [Member] | Field Effect Transistors [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	11,000	3,000
Europe and Australia [Member] | Power MOSFETS [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	0	0
Canada and Latin America [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	14,000	13,000
Canada and Latin America [Member] | Power Transistors [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	7,000	13,000
Canada and Latin America [Member] | Hybrid [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	0	0
Canada and Latin America [Member] | Field Effect Transistors [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	7,000	0
Canada and Latin America [Member] | Power MOSFETS [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	0	0
Far East and Middle East [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	66,000	65,000
Far East and Middle East [Member] | Power Transistors [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	0	0
Far East and Middle East [Member] | Hybrid [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	0	0
Far East and Middle East [Member] | Field Effect Transistors [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	3,000	6,000
Far East and Middle East [Member] | Power MOSFETS [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	63,000	59,000
UNITED STATES [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	1,874,000	2,046,000
UNITED STATES [Member] | Power Transistors [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	407,000	300,000
UNITED STATES [Member] | Hybrid [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	856,000	1,100,000
UNITED STATES [Member] | Field Effect Transistors [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	134,000	196,000
UNITED STATES [Member] | Power MOSFETS [Member]
Revenues from domestic and export sales to unaffiliated customers
Revenues, Total	$ 477,000	$ 450,000