Author: dougie

PSU fickleness of Raspberry Pi

I’m not kind to my raspberry pi’s. I have a few, of varying pedigrees, tucked away in the attic or other inhospitable dusty places. A week ago, the imaginatively named pi2 went offline. Irritatingly, it takes the podium of my most inhospitable rpi, tucked in the attic, balanced on a rafter, in a tight spot an uncomfortably long crawl away from the hatch.

Still. Gotta be done. I’d tried switching it off and on again. Many times. That was easy enough, and can be done from a distance. Likewise, I cycled power on its network switch a few times too. I rarely go the wifi route unless it’s unavoidable. I mean, if you can get a power cable to it, it’s usually possible to get a bit of cat5 there too.

No joy. So I brought it down, blew out the dust, and plugged it in again using a spare PSU in my study. Nothing. Except a high pitch whine coming from the, well, where was it coming from? The PSU? The rpi? Yep, definitely the pi.

I’ve never skimped on PSUs for the rpi. I’ve never much understood them either. Opting usually for the recommended product rather than skimping on a cheaper option. Although buying anything branded on Amazon nowadays is a bit of a gamble. What you see in the nice picture is not always, or even often, what you get.

Still, here’s the situation. The rpi is a, er, well, what is it? It’s back up the loft, far away in dustville, but, according to the University of Google, it’s:

root@pi2-driveway:~# cat /proc/device-tree/model
Raspberry Pi 2 Model B Rev 1.1

… and the PSU that it had been happily running on since it was sent up the attic, was:

NorthPanda Model LA-520WF

In the study I plugged it in to a spare rpi PSU, an old RS favourite. And that’s where I heard the high-pitched whine …

  • Radio Spares – HNP06UK
RS HNP06UK-MicroUSB

I was assuming the rpi was goosed but had a final visit to the University of Google, and, even though the noise was definitely coming from the rpi itself, and not the PSU, I tried one more time with a different PSU.

AAA Products MUSB2A PSU

I’m not sure when or where I bought this. According to my Amazon order history I bought this item on the 6 aug 2017 for an anker bluetooth speaker. I’m guessing that whatever it was once bought for is now jammed in a power bank, and the PSU was no longer required, until now. I’m glad I hung on to it though, because it fired up the rpi fine, and it’s back up the loft.

Buff-tailed bumblebee on Beauty Bush

The North East Bee Hunt has been great for helping me recognise bumblebees in the garden. You don’t need to know much to be able to distinguish the common bumblebees. I’ve gone from “they’re all just bees” to being able to recognise the ones that come to visit the garden.

Tree bumblebees in blue tit nestbox

I was bemused and mildly perturbed when tree bumblebees set up home in a nest box normally used by blue tits. Just a neat socially-distanced two metres from where we sometimes sit out when it’s sunny. I suspected, rightly, that they were like the Borg, and would ignore us as long as they did not consider us an immediate threat.

There’s a really good article on the Bumblebee conservation trust website that explains all about tree bumblebees and their, at times, somewhat mystifying behaviour. For the moment, I for one welcome my new bumbleebee overlords, and, in a month or two, when they’ve packed up and gone, I suspect I’ll quite miss them.