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Messages - jone

17
Project logs / Re: Wireless home energy monitor
Hi Ian,

Yeah, I like the look of the OpenEnergyMonitor project. Don't think it was around when I built the first monitor, but if I were starting from scratch now I'd certainly check it out.

I've got a handful of XBee projects around the house, all pinging data back to my central server for monitoring, alerting etc. My server-side scripts are nothing flash, but I'm aiming to get them up on my site at some point.

Cheers,
Jon
19
Project logs / Wireless home energy monitor
I've had a prototype energy monitor running at home for some time, but I needed a another one to read a 2nd electricity meter.

So I took the opportunity to tweak the design and make my first SMD board. I've put some build notes and pictures on my web site, alog with links to the source code and schematic/pcb files.
http://http://www.dresco.co.uk/projects/energymonitor

[attachment=3]
[attachment=2]
[attachment=1]
[attachment=0]
Hope it's of interest to someone, I've got a few more projects I want to document this winter, so any feedback welcome ;)

Jon.
20
Project development, ideas, and suggestions / Re: Low-loss battery supply regulator (buck/boost)
[quote author="bearmos"]It actually sounds like the chip uses a buck/boost for 7V, then that 7V goes into an LDO for the 5V.  Obviously, this wouldn't be as efficient as a normal buck or boost regulator, because of the LDO.  However, the LDO will result in a cleaner output voltage, with (hopefully) none of the ripple you'd normally need to put up with straight from the switcher's output.[/quote]
That's what I was expecting before looking at the datasheet, but it reads (to me) like it's linear regulation until VIN reaches reaches a low threshold, when the boost converter is enabled. So I suspect it's not going to be as efficient as hoped for..

Quote
During normal operation, when the battery is healthy, the boost preregulator is completely turned off, reducing quiescent current to 65μA (typ). This makes the devices suitable for always-on power supplies. The buck-boost operation achieved by this combination of LDO and boost preregulator offers the advantage of using a single off-the-shelf inductor in place of the multiple-winding custom magnetics needed in typical single-ended primary inductor converter (SEPIC) and transformer-based flyback topologies.
21
Project development, ideas, and suggestions / Re: Low-loss battery supply regulator (buck/boost)
If I'm reading the datasheet correctly, I think it's working differently.

My understanding is that if the input voltage is over a specific threshold, it purely uses the LDO. Once the input voltage drops under this threshold, it adds a boost regulator to provde sufficient input voltage to the LDO.

Btw, looks the the boost regulator and LDO output voltages can be set with resistor dividers, so should be possible to make a 3.3v / 5v selectable board.
22
General discussion / Re: Upverter editorial, original copy
[quote author="spanner888"]... just hijacking this thread in a slightly different direction...[/quote]
Thanks, is some interesting reading there & on the mailing list, can only be good news!
23
General discussion / Re: Upverter editorial, original copy
[quote author="arhi"]serious problem I have here is - CONNX has 5 pins. The symbol has only 5 pins, not 10, not 200, to choose a footprint I can't select only 5 pin footprints, kicad gives me choice from "all" footprints it has. That's not what I see as useful in any scenario.[/quote]
FWIW I think the issue here is that the footprint associations are made by name (wildcards supported), so it doesn't actually have any inherent logic to show only footprints with 5 pins. It's something that could be taken care of with a decent naming standard in your personal library, but then we're back to the argument regarding everyone maintaining their own libraries. :)
24
General discussion / Re: Upverter editorial, original copy
Yeah, I'm not going to try to defend the standard library, it's a bit disjointed.. I've started creating my own schematic and footprint libraries, which works well enough for me.

I can certainly see the advantage of back annotation, but it's not something I've personally felt a need for (have got used to the workflow of pushing a change through schematic->netlist->pcb).  Although I must say I pretty much moved to KiCad straight from paper & pencil, so perhaps I just don't know what I'm missing.. ;)
25
General discussion / Re: Upverter editorial, original copy
[quote author="arhi"]KiCAD don't have default footprints attached to the schematic symbols (nor a way to define them), KiCAD don't allow you to set "what footprints this part exists as" so that you can make a usable library...[/quote]
Must admit I'm not sure about a default, but you can certainly set a list of footprints for a part. I've done that just recently when adding an MCP1700 LDO to my library..
Code: [Select]
$FPLIST
  SOT89
  SOT-23A
  TO92-INVERT
$ENDFPLIST
Regards,
Jon
26
General discussion / Re: Hand soldering surface mount devices - footprint sizes
Thanks, so say I've tacked one end of a passive, when I go to solder the other end it doesn't seem like there is going to be much pad extending past the component? Is something like 0.4mm enough to get even a fine tip onto the pad as well as the component?

At least if I order the boards from Seeed/ITead I will have plenty of spares to practise with ;)
27
General discussion / Hand soldering surface mount devices - footprint sizes
Hi, I need to get some new PCBs made for an old project, so I thought I'd have a go at changing it from through hole to SMT. These will be my first surface mount boards, which I will be hand soldering, so am after some advice on footprints.

For instance, the standard KiCad 0805 footprints appear to have around 0.4mm overhang at each end of the component. My gut feel is that's a bit tight, would I be better off extending this to give me a little more room to work with? Or does enlarging the pads give me another problem I haven't thought of yet?

Thanks,
Jon
28
General discussion / Re: Site update changes and bugs
[quote author="ian"]Unread posts are blue, normal is gray I think.[/quote]
Ah yes. It's much better than the previous theme, but that unread distinction was a bit too subtle for me ;)

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