The Difficult World of Relays

The Difficult World of Relays

Before transistors were created in 1947 by American physicists John Bardeen and Walter Brattain and vacuum tubes in 1908, electric circuit switching between on and off was a purely physical, mechanical process done via relays (invented in 1809). Some people have made whole computers from relays. But as ElectroBOOM comedically describes, there are a lot of difficult problems that relays had to be overcome which leads to an amazing number of trade-offs of speed, heat, longevity, safety, etc.

While we consider flipping circuits on/off in the GHz range (1,000,000,000 times per second) common on today’s modern transistor-based circuits, many of the same problems he describes here exist in some form in transistors (switching time, etc). Instead of the more mechanical issues/solutions relays use, transistors solve related problems with the types of substraits, power properties, etc.

At any rate, it’s a great trip back in time and a reminder that engineers know that while a concept looks very simple on paper, the devil is in the details – and sometimes those devils take decades to work out (if ever).

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