Test apparatus for locating shorts during assembly of electrical buses

Claim 1

Test apparatus for locating shorts between electrical buses in a bus system having n buses, said apparatus comprising: means for generating pulses at a predetermined rate; means having n outputs and an input coupled to said pulse generating means for sequentially emitting pulses at said n outputs at said predetermined rate; a resistor having first and second terminals, said first terminal being grounded; n indicator circuits each including an electric lamp coupled between said resistor second terminal and a different output of said pulse emitting means, said output pulses from said pulse emitting means causing said lamps to be sequentially energized at said predetermined rate and a maximum voltage V to be produced across said resistor when no buses are shorted together; a single conductor linking each indicator circuit lamp to a different bus; a comparator having first and second inputs and an output, said first input being connected to said second terminal of said resistor; means for producing a fixed voltage slightly greater than V and applying it to said second input of said comparator; a sonic alarm; means coupled to said output of said comparator for turning on said alarm for a predetermined period and switching off said means for generating pulses when said voltage at said first comparator input exceeds said voltage at said second comparator input; a short condition between two of said buses causing: said voltage across said resistor to exceed said voltage applied to said second comparator input; said means for generating pulses to stop generating pulses; and said electric lamps associated with said shorted buses to remain illuminated until said short condition is removed.