Wall wart quality / stability

The other day I power-cycled my file server, and when I did so my edge router, plugged into the same power strip, took some kind of power hit and rebooted. It's Linksys EA7500v2 (running OpenWRT obvs.) which provides my internet uplink and feeds two local networks. Up until that point it had been stable, with months of uptime. The file server is no power hog and shouldn't have a massive inrush current at powerup, as it's based on a thinITX board, has no graphics adapter and is populated by just a couple of SSDs and a single mechanical drive.

This sensitivity to momentary changes in power condition bothers me from a reliability standpoint. I need this uplink to be stable. Does anyone find that the cheap included switching power supplies that come with consumer routers aren't? Are the classic heavy transformer-based linear wall-warts more stable?

(For now I've moved it to a 12v PoE splitter, one which has proven reliable on an AP/switch where I've been using it for some months. But interested in other people's thoughts about this.)

Unfortunately many modern (cheap) switching wall warts are very sensitive to transients and brownouts. They have very small capacitors and often very little filtering.

Absolutely. There is just no beating a good transformer-style linear power supply for stability and reliability. All my best gear goes on linear power supplies.

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Buy a decent power conditioner and you’ll never have this issue again. I’ve got two Furman m8x-2’s. They don’t just provide clean power, provide multiple plug-ins, and protect from surges. Each plug is isolated from any others on the unit.

The only downside is if you do oversupply the unit and trip/blow the fuse, it will bring the whole unit down until you replace the fuse. But with smaller 9v-12v supplies, this’ll never happen. You’d have to be running massive compressors or PA’s off it to do that.

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Generally speaking It's not the size of the transformer that makes the difference here, it's the size of the capacitors within the adapter. If your aim is to try to sustain power through small transients and you want to do it the hacky way, you could always just add some capacitors. To do it more robustly, a proper power conditioner, or better yet a UPS, will do the trick.


Most most linear/transformer power supplies have beefier capacitors.

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Yup... but it wasn't the transformers themselves... it was indeed those huge caps they used to have. A switching supply with a big cap would achieve the same goal.


Thanks all. I suspect a wall wart meant for pro/prosumer audio gear might be the best solution: they have to be protected against transients and noise and are usually transformer-based for that reason. I have one for a Yamaha midi generator that's a perfect match. I may just order a factory spare for that and use it on the router. And this time plug it directly into the UPS, not via a cheap power strip next to a much bigger load.

FWIW, I just checked my E8450/RT3200 power supplies again, because I remember being surprised at how tiny they were when the routers arrived.

One thing that I immediately notice is that unlike my older Linksys WRT1900AC 12v center +ve wall wart, these new PSUs aren't "Linksys" branded, and they aren't marked/rated/tested as an "I.T.E. Power Supply".

Now pretty much every high-quality computerized device (including music equipment) that I've bought in the last 30 years with an external PSU has specifically come with an "I.T.E. Power Supply", and it's one of the signs-of-quality that I've looked for when replacing a lost power supply (I don't remember one ever failing on me).

After these comments, I've just decided to use the old Linksys "I.T.E. Power Supply" on my main E8450, and will look in my large box of old PSUs to see if there's another one that I can use for my RT3200.

The One True Answer. :grin:

We moved to the earthquake zone (southern California) 15 years ago, and I started putting UPSs everywhere, as nothing else helped with all the transients (up and down) and frequent power dropouts that plagued all of our office and home electronics. When I reach the end of the line, they'll probably bury me with a UPS, just in case.


I’m in NorCal and our power has actually been largely reliable. But ups backup on the network infrastructure and other stuff that doesn’t like glitches is key.

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As noted above, though: plug sensitive items directly into the UPS; don't be tempted to use a power strip or multi-outlet extension cord to increase the reach and number of outlets and expect things plugged into it to still be protected from each other.