Been busy

First of all, I must apologise for my poor attendance lately.  No excuses, I’ve just had other things to do.

Second: In case you don’t know, you can click on the photos on here to see a larger version.  If you do, you can get back here by either pressing the ‘backspace’ key on your keyboard, or by clicking the big left-pointing arrow at the top of the window.

Now to the post.

As you all probably know, I’ve been playing with computers for many years now.  (Decades, actually… Oh boy, do I feel old! It’s over thirty years ago that I first had a play with one.)
Back to the point.  Over the years, I’ve also had an interest in electronics, but never really been able to get my head around it.

Until now.

In the past, I had a kind of blind spot with electronics – I knew the parts, but not the whole.  (Like a book in a foreign language: I could read every word individually, but none of them made sense, and when I finished reading a sentence I still didn’t know what it said.)
I could never understand, of instance, why an electronic circuit needed transistors.  After all, a transistor is just a switch – you use them to turn things (other components) on or off.  And if I want something on, I’ll turn it on.  With a switch.  So… why transistors?

What has changed, for me, is that I started to play with a microprocessor.  I got a little computer, about the size of a pack of cards, that I can plug things like resistors, LED’s, switches and buzzers into – and then I can write a program to tell them what to do!

I’ve been playing with this.  I’ve done things like wiring up an LED so that it will light up when it’s dark and go off when it’s light; for a few days I had an aluminium foil dog food tray on my desk, and if I touched it an LED lit up – and stayed on until I touched the tray again; I’ve reverse-wired a buzzer so that if I tap it, it prints ‘what?’ on my computer screen – tap it harder and it says ‘Ouch!’

And then I wired up a laser trip-wire.  And a sound sensor – any noise over a pre-set level will send a warning to my computer.

My little project

My little project

And then I made this:

‘This’ is a device that I can plug my laser or sound sensors into on one side, and a camera, flashgun, or both into the other.  And when something breaks the laser beam, or makes a noise, you get a photograph.

Ignore the red tag and black line on the screen – they are on the protective cover that I haven’t removed yet.

I had a lot of fun putting that together.  And just as much fun trying to find out why it didn’t work, and then getting it to work.

Today, I gave it a little try.

I had a few problems getting this.

Two lumps, please

Two lumps, please

I set up the shot as I wanted it, and tested it – and the flash didn’t fire.  My first thought was that I’d made a mistake in my wiring somewhere, so I checked carefully with no success.Then I wondered if the connection to the flash was at fault, so I tried another flashgun – which didn’t fire, either.  Sadly, the other gun was a different design – a very old one, actually – and needed an adaptor.   And it wouldn’t fire while it was plugged into the adaptor!

I spent an hour researching online, without any success.  I tried cursing, praying, screaming, all to no avail.

I’d already done basic tests, like ‘will the flash fire on it’s own?’ ‘Is there a bad connection?’ and so on – and I could get the flash to fire… sometimes.

I was using the flash off the camera, of course.  Modern cameras have a rather slow reaction time.  From pressing the button to actually taking the photo will take between 114 and 276 milliseconds on my camera, for instance.  (That’s between a tenth and a quarter of a second.)
Too slow for us to notice, yes, but when you’re trying to photograph something like this, it’s a lot.  I held those sugar lumps nine inches above the cup, and they hit the coffee around 250ms after I released them.  If I pressed the shutter release button at the same time – I’d miss the photo!

A flashgun, though… the reaction time on those is a lot faster.  So what you do is work in the dark, open the camera shutter, drop the sugar, fire the flash, and close the shutter.

So, the flashgun was on a little stand that came with it, and attached to the trigger device with a cable.  And I realised that the flash would fire if I didn’t use the stand.

A little looking, a little thought, and I worked out that the stand was designed to be used with the flashgun in ‘slave’ mode.  (You set it to fire whenever it sees another flashgun fire.)  On the bottom of the connection was a little button type thing that was pushed in by the stand – and it turned off the cable connection!

Two minutes work later and there was a hole in the stand, and the flash would fit in the stand without that button being pressed – and it would work with a cable!

I then had a pleasant hour or two dropping sugar lumps into hot coffee while trying to get a decent photo of it.

I’m quite pleased with my first attempt. 🙂

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