High power LEDs (by alaric)

I've got a few 3W RGB LEDs that I've been meaning to play with, so over the Christmas break, I decided to hook 'em up to the bench PSU and have a play.

As I have but one variable bench PSU with current limiting, I could only easily light one LED at a time. I didn't have big enough resistors to build individual LED current regulation circuits - I just set the current limit on my PSU to 0.35A and cranked the voltage up until it maxed out, hooked up to one LED in turn.

They are certainly dazzlingly bright:

Since the green and blue LEDs both have the same forward voltage, I figured I might be able to drive them together by using a pair of resistors as a current splitter, and setting the PSU for 700mA, thus ensuring that 350mA went to each LED.

However, my 0.25W resistors started to smoke when I got to about 400mA, so I shut it off - if one of the resistors burnt out then the entire 400mA would go into the surviving LED, overloading it (until its resistor also burnt out), and possibly making the thing explode. I ended up with a nice pair of burnt-out resistors:

Which is a shame, because I'd love to see how bright the thing is at maximum, with all three LEDs going!

My lab partner was most impressed, and asked me lots of questions about current and voltage; I had to resist her demands to keep making things, so I could go inside and write this blog post:

Falling over and bobbly knees (by sarah)

I've been having issues with my knee randomly swelling up and being painful then something at the back went pop and it looks all bobbly. Bizarlly this is niggly painful and feels like there is a string being pulled in the back of my thigh. I'm assuming its a vien and am not looking forward to going to the drs again 🙁

The calf of the same leg is painful too.

Then in the last couple of days I have managed to fall down the stairs and then again in Cheltenham yesturday 🙁

I don't really know what happened - I'd got myself over tired taking Jean on all the fun free things in one of the parks and we had gone for hot chocolate to revieve us. Now I wanted to have another drink and sit for longer and maybe even sleep if I was at home but no - Jean still had fun things to do so we headed back (at my insistance - Al thought I was getting too tired).

I'm not sure if I slipped on ice, tripped over the curb or if like the stairs my legs just didn't do what my brain thought it had told them to do.

So I ended up laying on the pavement unable to get up with Al, and dad clustered around me and Jean telling passers bys that 'Mummy's fallen down'. The main problem being initially I couldn't say anything for pain - I'd put my hand out instinctively and had jarred it and my really bad shoulder. The arm, shoulder and my ribs hurt (not sure why the ribs hurt). Just rolling onto my back made my stupid pelvis go click.

A concernced lady and her duaghter stopped and wanted to call an ambulence - which sort of made me panic so I just said - 'No its just my stupid pelvis.' no thankyou or anything just dismissive behavoiur. On the off chance that she ever comes across this - Thankyou I was the lady in the rainbow jacket.

When I eventually got up right again I thought I was fine but could berarly walk 🙁 And the pain got worse.

I hate this - this is one of the reasons I don't walk along the foot paths on my own anymore.

I spent the rest of yesturday in a little ball of pain on the settee, doing heat treatments and what have you, then in a warm bath for hours - on the plus side it ment Alaric made the house a nice temperature for me.

Of course now my left arm is being all rubbery and my pelvis is mobile again - This does not make for a happy Sarah.

BlackBerry (by alaric)

Many moons ago I did some work writing apps for BlackBerries. I liked the things at the time; they seemed to be well-built, both from the hardware and software angles.

So when my mobile phone contract came up for renewal (meaning I can get a free new phone if I sign up for another two years), with my existing phone falling to bits and rather crashy, I was pleased to find that I was eligible for a free BlackBerry 8520!

The device is a nice evolution of the BlackBerry I was using back in 2004 or so; rather than the thumb-activated scroll wheel we now have a two-dimensional scroll thing that works like a trackball, but seems to really be the innards of an optical mouse, set up so it sees my thumb moving over a small plastic window. This works well, takes up little space, and has no moving parts apart from the click action when it's pressed in to select something. The one downside of the new hardware is that my original Blackberry had a reflective LCD; it had an optional backlight, but spent most of its time with it switched off, simply reflecting the light incident upon it (in colour!). This didn't make for vibrant, saturated, hues in photos, but it did save a lot of power, and meant that the screen was highly readable in the brightest sunshine.

There's a few rough edges in the software; my model lacks a GPS, and the supplied maps application lets me enter my home and work locations by typing in an address, then gives me the option to locate that from the current GPS position (which of course fails) or to look up the address - which also fails, claiming the state/province cannot be found. If I just put the postcode into the address and nothing else, it works - but only matches on the first part of my postcode, getting a location that's some distance away in my rural area. I'd like to have an option to choose the location I've scrolled the map to by hand, geocoding that doesn't suck, and no menu options about GPSes when I have no GPS, please.

The mail system tries to auto-configure itself. Which is a blessing, and a curse. I bet it's a blessing for many users, and their IT departments, that they can just enter their email address and password, and have the rest fetched. However, I have a funny mail setup; I have lots of different IMAP mailboxes on the same server, with usernames like "alaric-work". And there happens to be a POP3 daemon listening on the machine that hosts my employer's web site. So when I put in my work email address, it notices that the domain part of the email address has an A record, and it has a POP3 server, and that POP3 server has a user called alaric (which is the user part of my work email address) which it can log in as with that password - so it goes ahead and makes me a POP3 account... with the wrong username and wrong mail server. Which would be OK apart from the fact that there's no way of changing the protocol or username on an existing mail account.

The trick, it turns out, is to deliberately put the wrong password in on the initial setup screen. This causes the POP3 login attempt to fail, and the subsequent IMAP one (in order to be compatible with Outlook's autodetection, it tries POP3 before IMAP!) too; it then says it can't automatically configure me, and asks me to list username and mail server. It then proceeds to guess IMAP somehow (it still didn't ask me, and the machine has POP3 as well as IMAP on it), and pow, my IMAP account is set up.

Angel Jean (by sarah)

Friday Jean came home with a letter saying her costume needed to be in school by Monday - I had obviously missed a letter somewhere a long the line and didn't even know what she was supposed to be. She informed me that she was an angel and that she had to have silver wings.

So one Sunday afternoon, gaffa tape, cardboard and a trip to tesco's for some tinsel and we had a pair of angel wings complete with a mechanism for attaching them to her without pain!

If I ever get around to writing this up the instructions and step by step photos will go on Salaric Craft. The angel dress was a rehash of last years snow cloud costume.

The Art of Knowledge Unconference (by sarah)

This weekend 12-13 Dec 2009 in Bristol there is an Unconference part of the uncraftivism weekend and I am going to be reading some of my poems that I think appropriate! Like The Programmer's Lament and A Picture of Words.

Me and Alaric are hoping some of you will join us in Bristol 🙂

It looks like a really interesting event so I'm looking forward to it - lots!

BKU2009 on twitter and I think there's some online jabbery stuff occuring. There is also like a talk/culture cafe thing and a lot of free form stuff hence the Un- bit of conference!