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When using a protection diode if it blows it does its job and saves a much more expensive component from getting damaged or destroyed. That's all fine and well but I was wondering about how we then can design this diode to be more easily replaced. Perhaps even by less technically skilled personnel (if possible).

My first idea for this would be to use some equivalent to a fuse holder. I was unable to find anything and I've only seen other similar posts suggest the use of a header which seemed like a bad idea to me.

So my question of course does anyone know of some sort of equivalent fuse holder for use with other components such as diodes?

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  • \$\begingroup\$ Depends on the diode package type. \$\endgroup\$
    – Eugene Sh.
    Dec 7 '21 at 22:09
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    \$\begingroup\$ What do you mean by protection diode? To protect against what? \$\endgroup\$
    – DKNguyen
    Dec 7 '21 at 22:12
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    \$\begingroup\$ But when the protection diode failed, it already stopped protecting the circuit, and the circuit is now damaged. Would you explain what kind of protection diode you mean where it makes sense to replace a failed diode and expect the rest of the circuit to be OK? I gather if the rest of the circuit is OK the protection diode did nothing else than blow itself up so it is an useless component. \$\endgroup\$
    – Justme
    Dec 7 '21 at 22:21
  • \$\begingroup\$ you might be able to shoehorn some SMD diodes into one of the "2-SMD" fuse holders (with the matching size), but for the reasons mentioned it's a questionable idea. Also the contacts aren't the same, only on one side for the diodes, all around for 2-SMD fuses. \$\endgroup\$
    – Pete W
    Dec 7 '21 at 22:29
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    \$\begingroup\$ If a diode fails when it is supposed to protect a circuit from flyback energy, it suggests the diode is under-rated. Be more specific on the circuit that caused it to fail and make it more robust, rather than focus on ease of repair. \$\endgroup\$ Dec 8 '21 at 0:37
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You could put it on a PCB or mold it into a package, but it might be better to have a more robust design (or less sloppy customers).

One potential issue is that a blown fuse is typically “safe” if removed whereas a shorted TVS that is removed also removes the protection.

Maybe you combine a fuse and TVS into one 3-pin module. Especially since the blown TVS will take out the fuse too.

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  • \$\begingroup\$ I do wish everyone would just be able to solder on a new diode. This is a skill that should be taught to everyone in school in my opinion. \$\endgroup\$ Dec 7 '21 at 22:42
  • \$\begingroup\$ The particular usage I had in mind was simply keeping anyone touching an electrode from getting shocked. One-way flow only but how this applies to TVS is also something that'd be great. I like the ideas about redundancy with any form of ESD protection. \$\endgroup\$ Dec 7 '21 at 22:44
  • \$\begingroup\$ I do like where this is going though I've been sitting here thinking about this and an approach like that may work in some other situations where there are more components involved I'm definitely not forgetting that one. I feel putting it on a PCB would be too much for the few pieces I'm using here though. Molding it into a package though is a thought but then we're back to it requiring soldering so I might as well just stick with just a diode then. If I'm missing something and there's a solderless way to do it then that may be what I'm looking for here! \$\endgroup\$ Dec 7 '21 at 22:59
  • \$\begingroup\$ But if it falls out it's useless so I'm sure that adequately paints a picture of my troubles right there! Otherwise, I probably would've figured this out by now I think, but I'm stuck on it. \$\endgroup\$ Dec 7 '21 at 23:01
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    \$\begingroup\$ If you have a replaceable TVS, I would assume the user would remove the blown TVS and operate the equipment without the TVS. Sort of like using a penny to replace a screw-in fuse in the days of yore. \$\endgroup\$
    – qrk
    Dec 7 '21 at 23:47
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I'm not sure this is a good idea. I've seen fuse holders become loose and fuses improperly installed. If you do this with a fuse then the equipment simply doesn't work. However, if you improperly install a protection diode the equipment could continue to work under normal conditions...it just would not be protected.

Unless the diode holder would always fail safe you might want to try another approach, such as adding a second level of protection that would fail first. Make the second level protection easy to replace. If the second level protection is always installed and used properly then you save time replacing it, but if not you still have protection.

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  • \$\begingroup\$ This is a good point to raise here too. I know it'll be different for different applications to come to think of it. The redundant layer for TVS allowing them to be replaced is a good idea for rugged field designs in my opinion. I definitely don't like the idea of it coming loose and falling out but a solderless solution of some sort would be great as that's really the only way you could expect an end-user to change it. \$\endgroup\$ Dec 7 '21 at 22:41
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Diodes have polarity.
You will need to find something that cannot be plugged in the wrong way. And possibly prevent operation when its unplugged as well.
Header (pin sockets) do not work, since user can put the diode in the wrong way. You would need something 4 pin - one pair to break the power supply and one pair for diode.

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  • \$\begingroup\$ This doesn't really have relevance to the true question I was asking though. This is going off on a sidebar about the headers. I mentioned that I didn't like that idea in the original post and wanted to avoid sifting through a bunch of answers about that. That was my intent behind mentioning the fact that when I was searching for an answer before posting this I saw nothing but that, justifying me posting about it. \$\endgroup\$ Dec 13 '21 at 6:58
  • \$\begingroup\$ Also this really doesn't say anything more than I didn't already say about it with the original post. \$\endgroup\$ Dec 13 '21 at 6:59
  • \$\begingroup\$ However I read Your question, I do not see the polarity of diode mentioned, and that is important and not obvious for untrained personel. All I am saying is - whatever solution you come up with, make absolutely sure it cannot be plugged wrong way in. Diode is not a fuse. \$\endgroup\$
    – Thomas
    Dec 13 '21 at 9:56

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