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Q&A Driving relay, transistor keeps failing

I'm trying to drive a relay according to a 5 V digital signal, using this circuit: It works for a while, but then the transistor fails. When I replace the transistor, it works for a while again, ...

1 answer · posted 4y ago by Olin Lathrop‭ · last activity 4y ago by Olin Lathrop‭

Question relay

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Olin Lathrop‭ · 2020-06-13T17:29:41Z (almost 4 years ago)

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I'm trying to drive a relay according to a 5 V digital signal, using this circuit:

![Image alt text](https://electrical.codidact.com/uploads/jaoSLhmqwQB4NuE6jKBLknxS)

It works for a while, but then the transistor fails.  When I replace the transistor, it works for a while again, then fails again.  The transistor is rated for 600 mA and 40 V.  I'm only running 63 mA thru it, and the supply is only 5 V.  The base current is about 2.9 mA.  I'm only asking for a gain of 22, when the gain should be at least 40 at this current according to the datasheet.

What's going on?

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