Meet TJ-100

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Meet TJ-100, or just TJ to friends. He’s a happy little robot, but with a very clever ‘party trick’ - he can bring out the last remaining bits of electricity form batteries that would be normally considered flat. His eyes then shine out brightly!

And how does this party trick work? It’s a ‘Joule Thief’ circuit. You’ll find many references online; the history, examples of construction and the theory of how this ‘trick’ works. This is not a new discovery, one of the earliest references to the basic concept is from the 1930s

Origin Story

Having quite a few ‘flat’ batteries around thanks to the numerous kids toys, finding this circuit sparked my interest. Initial attempts to build this circuit weren’t productive. Not being able to find a decent inductor to do the windings, plus having only a very old collection of LEDs that are not efficient where, I believe, primary reasons for failure.

Move forward to mid-2019, and this I found this article

I knew I had an old transformer in the ‘junk parts bin’, and the feedback circuit where intriguing (plus also some newer LEDs where available). This was successful, and the circuit worked as expected, though I admit that the feedback part didn’t seem to work that well. But we had light! Hence I decided to drop the feedback element, the downside being never connect a full charged battery.

Breadboard circuits are all well and good, but I wanted to ‘make something’ out of this circuit, to try and put all those old batteries to use.

On looking at articles I’d seen several pieces of art made from old components, plus one Joule Thief in the shape of a person holding the battery. Two things then came together, I also spotted examples of using off-cuts of wood, bolts, nuts to make robot models. They are very effective, plus easy to construct. Joule thief circuit, plus offcuts of wood = TJ-100.

The use of the bulky transformer was an issue, how to work that in? But then another stroke of luck – in the parts bin was a Maplin metal detector project (30years old?) with the perfect ferrite rod with copper winding. One my shelf as well is a coil of enamelled copy wire on a wooden reel that is probably 60+ years old (this was from an uncle’s family, and I was interested in it purely for aesthetic reasons). But with enough copper wire, to make another winding.

Parts

All the parts where in place! Electronic and otherwise

Coil

I don’t know the exact number of turns on the original ferrite rod; the second winding I did directly on top. The wire is slightly thicker but done in the same direction. From the articles online, there appears to be large variation in the sizes and number of windings without obvious changes in performance.

LEDs

Two white LEDs put in series, these are new LEDs, forward volatage is 3v, with 20mA forward current.

Capacitor, Resitor, Transistor

Nothing special about the capacitor or resistor. The transistor is a BC109. Again this was from the parts bin and the choice is I believe not critical. The precise nature of how the circuit works is influenced by the behaviour of the transistor, but this is a level of detail beyond my abilities.

Battery Holder

Didn’t really have a single battery holder in the parts box, plus it would nice to be able to use both AAA, AA, C and coin cells. But then hit on the idea of using a couple of bolts, washers and some very small magnets. Put together these acts as very easy and quick battery holders.

How does it work?

Will leave a detailed discussion to other articles https://en.wikipedia.org/wiki/Joule_thief, but the basic operation is for the transistor to be turned on by as the base is connected via the 1k resistor to +ve of the battery. The second coil will build up a large magnetic field, this will inhibit the current flowing to the base of the transistor, hence switching it off. However, there is still some magnetic field in existence, this will collapse and in doing so induce a current that flows through the LED.

This process repeats, somewhere between 5kHz and 50kHz. Hence to the human eye the light is continuous.

Construction

Using wood from an old dining table, the robot body was quite easy to build. There was already a hollow notch cut out that just happened to fit the ferrite rod and coil. I opted for the freewire construction method, by choosing a ‘junk’ style of construction means that the you can get away with a few imperfections!

I used a few old eyelets, and some solid copper wire. Which is difficult to solder without additional flux, and sanding the surface first.

Performance

I haven't quantified the performance; it works with a bright light from a very flat battery. Functioning in a model was my objective. It's hard to give an idea of relative effect, but by the image flare you can get an idea how bright the LEDs are. And from the battery meter you can see how low the battery was.

The End

There we go, one project ticked off and done 🙂

Raspberry Pi: Any my password is..

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.. well not raspberry, and not the usual form of passwords I use, and not written down in 'Electronics Log Book'.

To be far this PiZeroW hadn't been started in a while (too long) so my own fault. [insert your preferred search] to the rescue as usual. This page was the real help; to summarise the steps then

  • take out the microSD card and connect to computer
  • Open cmdline.txt and add init=/bin/sh to the command there (this is in 'boot' that Windows or Linux will find)
  • microSD back to Pi, and boot
  • Will boot straight to the command line, if it appears to be stuck hit return a few times to confirm the prompt is there.
  • su to become root user
  • I had to make the filesystem writeable with mount -o remount,rw /dev/mmcblk0p2 /
  • passwd pi to reset the password to *********
  • shutdown -p to shutdown
  • microSD back to the computer to undo the changes to the cmdlint.txt
  • and then back to the Pi

Though I had to to put the Pi case back together as it is an acrylic layered on that promptly fell completly apart. (Extracting the microSD initially required taking the case apart slightly).

Lego Clock: tick #1

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Several weeks ago, my eldest son's school topic was time.  Excellent I thought - the concepts of how we mark time seem to be very hard to explain to children. In previous topics we've been able to use Lego bricks, to help explain concepts such as multiplication. "Would we be able to use Lego to help explain time?" I wondered.

This was the start of a small obsession that has culminated in building a Lego clock-like mechanism.  To explain clock-like I decided early on to have a few rules.

  • This was a Lego clock, not a clock made out of Lego. So only Lego pieces, and do things the Lego way.
  • It doesn't matter that the brick colours aren't co-ordinated. As a 'Master Builder,' you use what you have available.
  • I wasn't worried about have 1 week between windings, or having to accurately match a modern clock. So long as it was approximately correct, and could keep going for a few minutes.

I have always had a fascination with time pieces, especially older mechanical clocks - we have a long case clock ourselves. Figures from history such as John Harrison are an inspiration.  Other inspirations to this design are two notable websites. Firstly Paul Sariel's tutorial on Lego Gearing   - how I wish I'd found this when I was 7!

Secondly, to  Ben Van de Wall's superb YouTube channel - from which I've attempted to replicate this escapement. The work on display there is extremely impressive. I believe that this is the most critical and important aspect of any such time piece.

To the clock!

Let's just head to the video, shall we?

What next?

I admit I don't really want to modify or change the design - it's workable and it has proven an interesting exercise. Plus I don't want to get too obsessed!

The plan, however,  is to share more details of its construction - especially to promote STEM and interested amongst children to get into engineering and the history of science and technology. What's of most interest to know?  Would like to show how the time gear train works - but with a motor attached so it's not going to be long video!

Raspberry Pi: my 3rd-ish bite

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So finally got around to getting the Raspberry Pi out of the bag and connected up 'to do something'.. well not quite sure what yet, but at least it's out of the bag.

To be far it has been used so far for a quite trial of XMBC and also of volumio; both looked promising for one idea.  I did attend a IET workshop on using the RPI and GPIO with WiFi sniffing. That was very cool - but I couldn't get to keep the SD or the Wifi dongle used there.

So I've setup the latest Raspbian image (had to use Windows not Linux as that seemed to failed to write the SD card. But maybe in hindsight it  was a faulty SD card?) ... A tutorial by Neil Black is very good intro and has a few good things I'll be referring back to.

Now to the WiFi - well it seemed to go quite well following this tutorial - but could I get it register a IP address? I did spot that had 'manual' not 'dhcp' but that didn't work.

So after a little stress I spotted this tutorial that had a subtly different set of commands.  Now that has worked correctly - and the Pi is connected over wireless (as well as via cable).  Looking back now though I did a general update of the software I didn't do the specific update as suggested for the wireless tools in the first tutorial. Maybe that would have made the difference?

Who knows for the questions? Maybe I should go back and test them out - but then life is short; it's working.

And for the 4th byte - maybe node.js or maybe wirless print server, or GPIO.. we'll see!

Photographer Links

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Last night I presented to the Fareham and Portchester Camera Club the 'Judging - a Personal Philosophy'. Seemed to go down quite well 🙂 And I learnt as well from the conversations with members. As a follow-on from last night this post has got the links to the friends that I've borrowed some images from. 

Many thanks to them - all three have shown me work that has inspired! There are also several other friends whose work is also very worth taking a look at; though I didn't get to show their work in the presentation last night. Perhaps a post for another day.

So working east to west in the world. 

So let's start of with Frances, based in Tokyo she has some great images of Japanese life, culture and landscape. Some very good recent images of floral still life. Flick link for tokyofran

Moving onto Humphrey Hippo; very different style from landscape, few portraits to  inspirational still life.  What I'm in awe of is her continued photo-a-day or 365 project. Well worth taking a look at.  Flickr link for Humprey Hippo, and the 2013 and 2014 '365 projects' 

Crossing the Atlantic now, we get to Alexis. Now based on Vancover, Alexis is specialising in city, land and sea-scapes. Flickr link for Alexis; worth also checking out Alexis Birkill Photography on Facebook. Lots of background behind the images. 

Finally and least here's my Flickr stream 

Again thanks to those letting me use the pictures and to those wishing to listen to me talk!

Cryptic Christmas Quiz – the return!

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After a year's hiatus the Cryptic Quiz is back! This featuring "Items that you can wear".  This year's quiz is now ready and waiting for you.

We don't managed to do one every year; typically breaks have been taken when just too much going on. And to be honest it's really my wife who comes up with the clues. I provide technical support. If you look back on previous years some of the more literal clues are mine; not really in the spirit of cryptic quizzes.

These can be passed around - really should put a proper license on them - but we've asked in the past to spare a small amount to a charity of your own choosing.

Answers are going to made available on line after Christmas; if you are really really stuck then a pleading email might do the trick!

Have a Happy Christmas! Don't get stressed!

Upcoming Photographic Judging

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So as a quick introduction I'm a certified Southern Photographic Federation Class B Judge. Meaning basically I can go to Photographic Societies within the SouthernFed's region and judge their internal club competitions.

After a brief hiatus whilst jnr #2 was born when I couldn't commit to doing any evenings out as of April I should be back!  So I've looked up the list of photographic judging that I'm been asked to do.

There are 6 dates currently booked into the calendar at a variety of clubs (Woolston provisional).  You're all welcome of course to come and see what goes on.

Of these I've only been to Marwell before. I'm really looking forward to going to Marwell - it's a small club but with some talented members and a very warm welcome (plus it's my first camera club!)

But equally I'm also looking forward to going to the other clubs.  Looking at their websites there all have talented members.

Within the camera club and photographic society compensation circuit I will honestly say that these competitions are strange beasts.  It's all too often to hear lots of comments about the randomness or odd remarks from judges (and I've made them myself to be honest).  Or for Judges to forget that they have haven't separated their own personal preferences from their assessment of an image.

As an aside for a different take on photo critiquing have a look at  this edition of XKCD.

But we still put these competitions into our society's schedules so they must be fulfilling some need (and I argue they do)

Last year I put a presentation together on how Judges think and critiquing photos.  I'm going to try and expand on that in an article to give some background to how I judge.  It's only fair I think to present the 'marking scheme'.

Animal Tales

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Dear Syndey,

Sorry for not putting beak to paper before now, but you know it is these days in the jungle. I don’t get the time to do anything relaxing.  When the wife’s ill and there’s the kids to look after, I don’t get the time. My son demonstrated to me his low flying capabilities which I advise him against using too often. It is surprising how many parrots you hear of these days getting wiped out by low flying. Fellow the other day got caught in a creeper and was strung up like I don’t know what.

I suppose you don’t get much chance to do a spot of flying. Anyway I don’t see much need for you to fly around since you’ve got it all laid on, a nice warm cage, food and water whenever you want. We don’t have such luxuries here.
The main reason I write is to tell you the latest about is happening my area. I said the wife’s been ill, well for a treat for her and the kids (I stopped my son’s low flying antics), I took them to a small spot I once discovered on my travels. It is a nice spot with a large selection of food if I remember rightly. When I arrived had quite a shock. Just before we arrived we stopped for a little rest, and I had a little look on ahead to see if were on right track since it was long time since I was in that area. When I flown a few vines further on, I though I head a strange sort of noise, not one which I had ever heard before. Being an inquisitive sort of bird I ventured even further. Quite a number of vines later on I came to what I believed was one the clearing that I remembered. However, I discovered to be horror and disgust that the humans had transformed it into one of their massive great hard grey things that I had heard about on grapevine. From what I could see, it covered an area thousands of us parrots could live in and it would take several days to travel the length of it. My wondrous clearing had been totally destroyed along what all the food in it. I notice several other parrots around about so I went over and introduced myself.

I don’t really know what this object was supposed to be and the parrots showed me some other humans who apparently were not in favour of this thing. They had sticks and were throwing at this noisy yellow object, that was lurching around the place. Apparently they had once lived there and now they had nowhere to live. Some other people had pieces of wood which they had written “NO BYPASS” on.

Well I don’t know what the world is coming to, really I don’t. I must fly on now.

Regards, Wilberforce.

Thoughts on Focus-on-Imaging 2011

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As promised some thoughts on Focus 2011. Overall another worthwhile trip I feel.

Arriving a little earlier than in previous years was a bonus; gave a little more quiet time to review what was there and determine a plan of attack. It was noticeable I think that there were a few less exhibitors than in previous years - the noteable absence of Canon for example. It also felt a little less crowded, not so much pushing and shoving to get somewhere. Or perhaps this was just because with fewer stands everything was spaced out more. I also noted sadly there were no public address announcements when a talk was about to start; nor is they any central list of the talks. A real shame as I had hoped to pay more attention here this year.

After a coffee and bacon bap (so important to stay hydrated and feed as it's a non-stop day)  first stop was as planned Nikon. So D7000 D300S and D700 comparison. My comparison here was purely ergonomic - all are good specifications and all better than a D100! The broad decision was easy to make - I picked p the D7000 and then put it down again. Ergonomically it is just felt 'wrong'. Comparing with a D300s/D700 body showed quite a lot had been taken off the left hand side. With the grip on the bottom the D7000 became a square box with a lens at the top left corner - not at all balanced.

If I had to buy a camera today - D300s; however it's coming to the end of its life. D700? well with DX lens this crops down to around the D100. A few more pixels are now required really.  Upshot? Well the money is not quite yet in the account so it's a wait and see game?  Can I last until the D400 or D800?  D800 full frame is very tempting - lower noise and get to use the old FX lens as they should be used.

Moving to the Lee Filters, 'Big Stopper' talking to the Lee stand Speed Graphic decided not to bring any as they would sell out very quickly. (Business model fail?) So Linhof got the order (as they had some but had sold out).

PhotoBox next to talk about their calendars in loci James. Well the couldn't say what the aspect ratio was, not were overly  keen to find out. But were firmly of the opinion that the templates in the calendar tool would permit the layout that is required without any needing to know the ratio. Plus that the mix of colour/b&w wouldn't compromise the image quality. In fact the example calendar on display was a mix and had good definition.

Epson's new printer is big - but not as I had imagined another replacement for the replacement of the R2400; the R2880 still stands. This new printer is filling a new need apparently. They did confirm that servicing a printer that hasn't physically failed or has demanded servicing is not reqiured. My drifting black point is most likely my colour management.

So what else?

  1. Spoke to Joe Cornish and Eddie Ephraums about their new book (signed copy obtained)
  2. Paramo have indicated to me to send back my jacket so they can remove the lint it's picked up over the years (a common problem now especially with merino wool.
  3. Brilliant Prints impressed me with their canvas prints, very good quality printing and physical construction. Reasonable prices, good guarentee and a passion for the business which is so important.
  4. Drobo always impresses me; especially this year when I got to start pulling out drives live and putting them back again.
  5. Last year I was smitten by a new monitor, and so this year. NEC PA-241W is simply outstanding - and one of the lower end models. Maybe if I wait for the D800 I might be tempted with a new monitor.
  6. Loxley Colour was also a stop; having been impressed with some prints for Alexis, I wanted to stop buy - they do calendars (yes finally I can get competent calendar!) and lots of other things.
  7. Sony had a very impressive stand and display, no doubt trying hard now that a certain big name was missing. Yet not many people around the stand.
  8. Panasonic though had a good showing for the Lumix G series. An impressive concept with a growing lens collection. It's a very tempting proposition I must say. Indeed one I would possibly recommended to anybody starting. (Although it has to be said the D3100 is also very impressive - although so very very small!)

I must give an honorable mention to the vice-president of the RPS - as I challenged him to explain why I should join. I do applaud and support the concept of the awards and have seriously been working on and off to the 'L' Panel. Yet reviewing the cost of the RPS  - now at least £100 a year - I need to ask what I would get from it. To be fair the answer is really - how much can you put in.... the problem is that with the amount of time free for photography the RPS would always for me a the moment a distant club. I applaud the work they do behind the scenes... but sorry at the moment £100 is better spent on other areas of photography.

So finally to the end of the day, a quick trip to the Hahnemühle stand for their discount on paper. Also picked up a DIY Canvas kit for £20 - worth a try. Also just looking at their site I realise that I was quizzing one of their top directors about how curl a roll sheet of paper would have when mounted.

Also picked up a new Nomad print box (growing print collection) - these are simple boxes but simply brilliant. Did get a soft sided cases for taking to club print evenings.

I did finally pay another visit to Nikon - was my initial impression right from earlier in the day? Yes - no question. So the matter remains now, need to get the money into the camera fund. When it gets to the suitable level - where are we in the year.

 

 

Focus-on-Imgaing 2011

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It's that time of year again when I take a day off from the job that pays the bills, to spend time at the job that creates the bills.  That is I'm going to Focus at the NEC on Monday.

One reason I go is primarily to spend a day with photographers, cameras, gadgets and photographs.  Generally I don't go with a shopping list - as I know that I'm going to be tempted to get something. Plus to be honest the prices are not that greatly reduced I find.

So what am I looking for this year?

  1. D300S or D7000 - need to go and hold these and see really which I want.... money is now there to replace the D100 - it's getting to the end of it's life.
  2. Lee Filters 10stop filter - will probably buy this there.
  3. Attend some of the talks - never really done this before as I've always just spent the time wandering around all the stands. But as a lot of these are the same year-on-year time to get to some talks.
  4. Look at the new Epson printer that is a several generations away successor to the R2400

Often I've been with James but as he's doing his day job this year I'm going to head over to PhotoBox and find out really what the aspect ratios of the apertures of the calendars are! Plus why the Blacks on mixed colour/monochrome products aren't black.

Although I can't promise anything if there's some burning question you think could only be answered at Focus, post a comment and I'll see if I get it answered!

Will post back next week.