Browsing Posts published on 19/10/2010

Save Our Bees

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Save Our Bees!

Save Our Bees!

Save Our Bees!

Save Our Bees!

SAVE OUR BEES!

With the blessing of our neighbours, LEAF have recently given home to a family of bees on our Norwood site.  Beforehand, we liaised with our neighbours, fellow plot holders and the council’s Allotment Office.  They were unanimously in favour because we all know that bees mean…

better pollination of crops

which in turn means

a more plentiful harvest

However, it has come to light that a small but vocal minority are opposed to the bees remaining at LEAF.  We find this difficult to believe.  How could bees be anything but good?

REASONS TO SAVE OUR BEES

Bees need your support! The UK honey bee population is in decline and the British Beekeeper’s Association has stated that if positive action is not taken immediately, Britain’s honey bees will disappear by 2018!

Bees help make our food! 3 out of every 4 mouthfuls of food we eat are directly or indirectly the result of the work of bees.  Most food crops are pollinated by bees, and if the bees disappeared the crops would fail.  If this happened on a worldwide scale, the whole world would starve!

Bees keep Britain blooming! Bees pollinate the flowers in your garden, in the park, in wondow boxes -without the bees, the world would be a much less colourful place!

Bees are FASCINATING! This is a unique opportunity for local people to learn about bees and how they live.  If we don’t act now then the only way to learn about bees in the future may be in a museum.

WE NEED YOUR HELP!

We at LEAF believe that a world without bees would be a terrible place and that we should do all we can to help them.  If you agree to this, then please register your support by sending your details to bee@leafsheffield.org.uk – Thankyou!

(…Of course, your privacy matters to us, so we will under no circumstances pass on your details to a third party…)

And yet more problems.

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So, flushed with the success of getting my PIC programmer to work via the 5 pin ‘ICSP’ (In Circuit Serial Programming) pins and lead, yesterday I carried on with the code…

…And started to notice yet another problem.

It seemed that the circuit and code were unreliable.  I’d be sitting pedalling like crazy on the bike, when the PWM would stop working, making it exceedingly easy to pedal.  Luckily, I managed to catch myself before an expensive trip to the dentists was called for.  Unnerving, and certainly no good for anyone else to use.

I thought that the power supply lines going to the chips was ‘dirty’ with noise and spikes.  A reasonable assumption, I thought.  Sure enough, I checked with my new ‘scope, and saw that the lines were indeed dirty.  So, yet another trip down to Maplin’s  late yesterday afternoon to buy some ‘de-coupling’ capacitors, and on getting back and fitting them it did make a difference, but didn’t eliminate the problem entirely.

I then recalled my efforts with the little PIC16F684 and how it had been so well behaved.

Why? I asked myself.  Why, oh why, oh why…

And then I got the germ of an idea.  Maybe an inkling of one…

Going back to the original PIC16F684 programs, I went through them line by line, then went over the settings on the PicProg2009 assembler I use.

And I found it!  In the ‘configuration’ settings -the ones ‘hard-wired’ into the coding- I found discrepancies.  I won’t bore you with the details, but suffice to say that when I’d reset them -before I’d even got on the bike again, I knew I’d solved it.  A real “Whose Cat??!!” moment, you might say.

So, today I’ve been down to Maplin’s yet again to get the more bits that will enable me in the coming days to combine my circuit with the programmer.  I also bought another cheapo ‘scope probe so I can see two different points of the circuit at the same time.

Now with two traces.

Now with two traces.

If you look at the image to the right, ignoring my reflection, you can see the top trace with the ‘spikes’ in it.  This is the waveform going into the gates of all four of the FETs.  Remember that these FETs are in effect ‘active low’, so the time that each FET is ‘on’ is the flat part between the spikes.

The lower trace shows the voltage at the output of the FETs before any smoothing takes place.  The ‘double dip’ beneath the top spikes is the recovery diode kicking in to ‘dump’ current in the right direction from the inductor just ahead of it in the circuit.

So, now I’ve got those extra bits it will mean that when I’ve got the new circuit built, probably tomorrow afternoon, rather than having the computer plugged into the programmer which then plugs into my board, I will have a board (…soon to be in its own box!..) that plugs directly into the computer via a standard 9-pin serial lead.  This will then of course mean that I can plug the ‘new’ laptop into it as they did in the film ‘Aliens’.  Given some of the current ‘challenges’ we’re facing at this particular time (…See the ‘News’ heading very shortly…), I’m beginning to wish I had built a couple of ‘Remote Sentries’.

Oh, and given Sigourney Weaver a call.


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