Business Segments - Schedule of Financial Information Relating to Industry Segments (Details) - USD ($)	3 Months Ended	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2019	Apr. 30, 2018
Total net revenue	$ 3,574,000	$ 14,126,000	$ 11,931,000
Total income from operations	814,000	3,306,000	2,492,000
Total depreciation and amortization	106,000	354,000	257,000
Total capital expenditures	66,000	154,000	533,000
Total assets	43,027,000	43,027,000	40,942,000
Security Alarm Products [Member]
Total net revenue	2,872,000	11,006,000	8,423,000
Total income from operations	654,000	2,656,000	1,759,000
Total depreciation and amortization	38,000	95,000	37,000
Total capital expenditures	39,000	75,000	280,000
Total assets	6,179,000	6,179,000	4,561,000
Cable & Wiring Tools [Member]
Total net revenue	527,000	2,431,000	1,326,000
Total income from operations	120,000	488,000	277,000
Total depreciation and amortization	31,000	123,000	62,000
Total capital expenditures
Total assets	2,713,000	2,713,000	2,347,000
Other Products [Member]
Total net revenue	175,000	689,000	2,182,000
Total income from operations	40,000	162,000	456,000
Total depreciation and amortization	19,000	74,000	103,000
Total capital expenditures	19,000	56,000	172,000
Total assets	842,000	842,000	1,521,000
Corporate General [Member]
Total depreciation and amortization	18,000	62,000	55,000
Total capital expenditures	8,000	23,000	81,000
Total assets	$ 33,293,000	$ 33,293,000	$ 32,510,000