Abstract: A mini-relay signal tester designed to simplify, speed up, and test the operation of "mini" or "reed" relays which are suspected of intermittent failure. These types of relays are extensively used in memory and gate-array testing systems and their failure can cause the semiconductor devices being tested to be erroneously rejected. The relay tester dynamically exercises the relay being tested by application of a square-wave input signal to its coil. The square wave input "reference" signal driving the relay coil is then compared to a square wave output "test" signal which is generated by the contacts of the relay being tested. The signals are compared on a dual-trace oscilloscope. When difference between signals exceeds acceptable standards the relay is rejected.