If you’re not short on cash, then the Chip Tester Pro may be more to your liking, however it’s hard to beat the simplicity and thriftiness of building your own simple tester from spare parts.

Testing relays and their circuits in vehicles doesn’t always require a trip to the bench. With a few simple tools and knowledge, this video shows how to test relays directly in your car using a test ...

You can build your own modern tube tester, of course. Or pick up a vintage one. Our favorite one uses punched cards.