PSU Voltage Spike

[planters]

Based on your recommendation, I looked into these and they seem elegant, but potentially design sensitive as opposed to simple resistors. If undersized the cap would be well below line voltage and they will have heated to the point that they no longer protect and if over-sized they will not heat suffeciently and the resistance remains high. This is I suspect less of a problem than I am making out, but is there a guideline re cap size/line voltage /NTC size?

[steve-o]

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is there a guideline re cap size/line voltage /NTC size?

Not that I'm aware of , but probably out there somewhere. Power supply design (non-switching) is something that has always been trial and error for me until I get it right. The basic transformer/ bridge/ cap/ regulator supplies are the ones I like because spikes are less likely to occur. I have never been a fan of the switchers because of the complexities of the designs (more that can go wrong w/ them).