Odds and Ends

Just a few odds and ends… we’ve arrived safely in Spain and I’m not getting quite as much blogging time as I’d like as there are repair jobs to do – but I managed a little item on Node-Red earlier – I’ve had people in here asking for simple-use examples – so that’s the first.

Gauge Progress: I’ve not forgotten my HTML5 Canvas gauge – it’s coming along nicely but along the way I’m hitting minor bottlenecks on image loading – and image pre-loaders are not helping. Most but not all of this came to light when I moved thousands of miles away from home with the attendant delays! I’ll return to this one soon.

Node-Red Menus: Regular readers may recall from earlier blogs that I’ve been griping about the menu in Node-Red being there even if you have only one page. Some may have noticed that a blog reader pointed out a simple CSS solution – well, now there is better – Node-Red master as of now has an option to turn the menu off. I’d give it a day before updating to make sure the latest version had filtered through to updates.

Mint Linux: I wrote a while ago about this – so often these things fall by the wayside – well, I’m still using it – can’t find anything wrong with it on my little black laptop.  It isn’t Windows but for development work – it runs a lot faster on that old hardware than Windows 7 did and everything works right down to my Logitech Bluetooth headphones. Anyone else using this on an Intel-powered laptop?

Raspberry Pi Power backups: You’ll probably know I’ve covered this in the past – various solutions for backing up the little SBCs in the event of power failure. My best solution up to now has been RavPower battery charging units – but not all of them seem to work in the same way. I did find a little LIPO unit that works on one round 3v6 battery but it’s power output would not work for a RPI3 for example (which takes more power than the RPI2. Well, I’ve just discovered and sent off for one of these. It’ll take a few weeks but I’ll let you know how that goes. Anyone bought something similar? How did that go for you?

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17 thoughts on “Odds and Ends

      1. i was thinking (yes, it happens 🙂 ): many of these ups boards are powered by standard microusb connectors, so 5V... what about 2 little wires soldered just where the 5V comes IN, then a basic voltage divider to reduce 5V to 3.3, and connect this 3.3V to a gpio pin of the raspberry, to monitor when there's a power outage... this way, if it goes LOW, you can trigger an automatic "Safely Saved System State Shutdown Script" (6S!) 🙂

        or, without soldering, a usb power splitter or whatever way to detect power outage... to restart we need an external device that triggers the 2 pins on the side of the raspberry...
        http://www.savagehomeautomation.com/projects/raspberry-pi-install-a-momentary-reset-button.html

        1. Better yet, as you don't want to turn the unit off when the power goes off but when the battery is getting down, simply monitor the battery voltage... it will always be 3.3v or so on charge - so a simple series resistor would do - and what you're actually after is maybe half an hour or so before it is too low to run reliably - turn the unit off. Clearly you'd need to average the voltage over a few minutes because you don't want to shut down just because of a sudden surge.

          1. mmm... where exactly would you measure that? Because generally LiPo are charged at 4.2, and their nominal voltage should be 3.7... sure you can anyway wait a while, so, even with my version, no need for immediate shutdown... but, let's talk, sure monitor batteries is better, while mine is just easier 🙂

                1. I did think of mentioning that - an old low-budget trick... however, it isn't that accurate because the capacitor will be temperature sensitive. Still, would be interesting to see if anyone has used this as a reliable indicator for this application!

    1. An interesting one Antonio (apart from the obviously increased thickness due to the type of battery used).

      I get incredible reliability out of Raspberry Pi and I'm looking forward to using these boards to further improve this. With careful use of software designed to work with SD (rather than hard disks) and solid supplies I could see my home controllers working for years without rebooting - which is how it should be.

      Of course I'm only dreaming as I won't be able to resist upgrading - just about now I'm about to try the new Node-Red UI upgrade.

      1. Yeah it's fabulous performance, no sign of any lags anywhere. This model is about 5 years old from the time when it was in production. It's discontinued now and I picked it up 2nd user refurbished to near new condition on ebay for £300 delivered last year. Great for a machine that used to be sold starting from £1200 for the models without an ssd installed.

        At the time when I was looking I wanted a lenovo thinkpad W520 or T550 because the keyboards on those are really good. But I couldn't find one at a reasonable price and if I was super critical I'd say the keyboard is where the elitebook is a bit crappy..no real complaints though. It's of high quality build materials, no flex or twist and it's certainly better than the poor old 6 year old acer that it replaced (this really is the state my old laptop had reduced itself to before it went to computer heaven):

  1. Hi Pete,

    I have an identical one of those chinese battery boards that you bought. I've had it for a while now. I like how it matches the form factor of a Pi so can be mounted above or below an RPi2/3 using standard PCB mounting hardware. I found it to be very good. Decent battery life on it despite the usual overly bright chinese power indicator LED. I was impressed as I had expected it to be pretty average given the usual rule where you have to divide chinese power/speed/capacity units by 2 to 2.5 to get the real figures. I think you'll be suitably impressed, certainly for the low price.

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