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I'm designing a board for the first time. There is problem. Because of the problem, the circuit may not work effectively. I was asked to resolve the hardware design related review point:

Diode at Relay for back EMF protection

What does this mean? What do I have to do now? What is the thing that I can do to solve this?

JRE
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Swathi A
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    Have you tried to search for “relay diode back EMF”? What came up? How do the results differ from your schematic? – winny Jul 05 '21 at 10:12
  • V=LdI/dt. = flyback V – Tony Stewart EE75 Jul 05 '21 at 11:54
  • Why don't you just ask for more clarification from the author of that design review comment? What you posted is rather cryptic. – SteveSh Jul 05 '21 at 12:00
  • N. B. You ought to read PCB Design Review checklists online too (e.g. Sierra Proto Express) and make sure you have good grounds and test points. – Tony Stewart EE75 Jul 05 '21 at 12:02
  • @TonyStewartEE75 God I love test points. Or rather, it's such a pain in the ass when you don't have test points and inevitably have to probe something about a hundred times over the course of a week. It's like not having a toilet when you need one and having to make do. And I'm not even talking about test points with nowhere to clip to. I'm talking about test points that actually run to a header that you can fiddle around to try and clip onto, let alone a trace or pad in the middle of the board. – DKNguyen Jul 06 '21 at 04:49

1 Answers1

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It means if you have a relay, that has an inductive coil, you need a flyback diode to avoid voltage transient whenever it is switched off, which can destroy your switching device (transistor supposedly).

Damien
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