Browsing Posts published on 02/10/2010

Now its getting really, really late, so this will hopefully be incredibly short, before I fall asleep at the keyboard!

While today, being Saturday was a Plot Day, yesterday I made great progress on the programming of the PIC16F684 processor currently being used in the bike generator.  We probably won’t end up using this particular little chip because it has ‘too few legs’ and therefore too few possible output pins which will be used in the ‘final version’ to provide fun things like 7-segment displays and indicator tell-tales.  Remember the ‘JBM’ and ‘JBCM’?  Stuff like that.  Luckily, the bigger PIC’s in the 16F series all have the same programming language, so porting the code over is no great shakes at all.

So, one of my main ‘challenges’ (…some would say ‘problems’, but I’ve been on all the ‘Positive Thinking’ courses.  Can’t you tell?..) was that the output of the generator varies wildly from a few hundred milliamps to quite a few amps just in the space of a single revolution of the pedals of the bike.

Why?  Well, if you think about it, it’s much more difficult to move the pedals when your feet are in the ‘six o’clock’ position -i.e. vertical, than in the ‘quarter to three’ position where its easy.

You may think you’re providing a steady pedal speed, but measurement shows its anything but!

What happens is that as your feet are in the quarter to three position, you start to pedal much faster, slowing down when your feet are in the ‘vertical’ position.  The circuit, because it takes a measurement so rapidly, senses that you are moving quickly when your feet are in the ‘quarter to three’ position and therefore putting more voltage into the battery, tries to accommodate for this by upping the current being drawn into it, bringing down the voltage accordingly.

This means that all of a sudden, its much more difficult to pedal.

So, you instinctively slow down.  The circuit sees this, and lowers the current being drawn.

This is certainly a little off-putting in action, not least because there’s a real danger of you losing your teeth to the handlebars as it suddenly becomes much easier to pedal.

The solution is an averaging routine, which as the name suggests takes quite a few readings, then gives out the average current, so the processor can make more of an informed decision.

To this end, I searched The Net, and while there are some excellent math routines out there, I couldn’t for the life of me find one which would take the ‘mean’ of several readings.

So I wrote my own!

Okay, I’ll stop bragging now, but suffice to say I can now take 4, 8,16,32,64, 128 or even 256 readings and find the average of them.

Tomorrow’s (…So soon to be ‘today’s’!..) task will be to write it so it takes say sixteen readings, averages them, waits for a short time (…in fractions of a second…), then takes another sixteen, and probably does that 4 or even 8 times over a two second period.  When it has all these averages, it will average them to provide and average, average reading.

This will hopefully completely smooth out the ‘bumpiness’ of the ride, and make any changes much more gradual and therefore unnoticeable.

Well, thats the theory.  I’ll let you know how it all turns out!

Anyway, this bunny is pretty tired, so I’ll leave it for there.

And the sun comes out! 02/10/10

Well, for once the weather people got it right today.

Yesterday was awful.  The kind of weather that as soon as you look out of the window in the morning, you want to go straight back to bed.

Unfortunately, I had to get out of bed yesterday.  If nothing else, I had a cat to feed.  As every cat owner knows: Hell hath no fury like a hungry cat. Fact.

But today dawned bright and mostly sunny, and thankfully it stayed that way all day.  I arrived a little late to find Diane chatting with Chairman Mick and David.

After a cup of tea (…obviously…), Barry, Sairah and little Adam arrived, quickly followed by Sara, Cloe and little Lisa.  Mick soon had to leave, but wished us all the best in our efforts!

The tomatillos in the greenhouse.

The tomatillos in the greenhouse.

While ‘The Girls’ busied themselves up by the metal shed, David, Barry and I set to work pulling sweetcorn, first from The Therapy Plot, then from down on The Demonstration Plot.  The old stalks and other plant-rubbish were placed in an empty compost bin down on The Demonstration Plot with layers of apple cores left over from the midweek apple pressing session.  These will break right down over the next twelve months or so, providing good compost for probably the year after next.

To the right here is a quick shot as I passed the greenhouse of the tomatillos, and on checking the ‘pods’, they seem to be filling out nicely inside.  A few weeks more, and as I have said in the past, we’ll be scouring the net for recipes.

After we’d emptied the beds of sweetcorn, we set to emptying a bed on the top plot.

This had been another experiment in the planting of different herbs.  In hindsight, we planted too many different types of herbs too closely, and didn’t delineate the lines of seeds properly, so when stuff started to come up, we didn’t know if it was a herb or a weed, almost until it was too late.

Consequently, this bed has been completely overrun by weeds and other ‘nasties’.  Apart from some very pretty variegated nasturtiums that we want to save some seeds from, everything was to come out.

Now, this is the kind of gardening I like!  ‘Scorched Earth’ as someone once put it.  ‘Slash and Burn’ to the extreme.

So, David, Barry and I started, and soon found the nasturtiums which Barry very carefully lifted so we could all plant them on a mound of well-rotted woodchip on The Orchard Plot.

This done, we set about the bed with gusto, soon to be joined by Gary.  This then freed-up David who wanted to string up some onions as he’d never done this before.

Well, Gary set about this bed like a whirlwind, almost putting Barry and myself to shame!

The bed emptied.

The bed emptied.

If you look closely, you’ll see that Gary has thoughtfully moved the earth away from the sides and ends of the bed.  This is to allow us access to it to re-stob it where necessary, ready for next season’s planting.

See how neat and ‘fluffy’ this soil looks?  This is down to Gary’s expert working of it, and also the organic ‘conditioners’ that have been added to it over the years.

The plan for this bed -at least for the next few months, is that we will empty one of the top leaf clamps of last year’s well-rotted leave mold and place it all here.  We will then use this bed as a source of leaf mold to be used in beds on the top plot over the coming weeks, and hopefully leave a layer of mold on top to prevent many of the weeds coming though.  The worms in the soil love leaf mold too, so no doubt they’ll be busy coming up to the surface, then dragging bits of it down with them.

As we’ll have a leaf clamp empty, it will allow us in the coming weeks to fill it with this year’s leaves ready for this time next year.  Long-term planning, but it has to be done!

Gary starts work on the path by the bed.

Gary starts work on the path by the bed.

Here’s a shot of Gary with the newly ‘prepped up’ bed on his right, busily bent over weeding the path running up besides it.

This path over recent months has become totally choked with strawberry runners and other weeds, so here he is clearing it, and next week he plans to wood-chip this and other areas he cleared today.

Meanwhile, ‘The Girls’, David and Matt were busy stringing up more onions, and here’s an awful shot of just some of them hung in the top wooden shed.

Strings of onions hung to dry.

Strings of onions hung to dry.

This shot is so poor because I didn’t want to use the dreaded flash on the camera, and it was really difficult to hold the camera still for such a long exposure.  Sorry!

So, this is just a few of our onions.  There are still many, many more to hang up, so we’ve certainly got our work cut out in the next couple of weeks!

Elsewhere on The Plots as I strolled round, I couldn’t help but take more shots of the beautiful borage.

Borage, still in flower.

Borage, still in flower.

This particular ‘clump’ has self-seeded on an earth pile outside The Demonstration Plot, and though you can’t really see them here, this group of plants was teeming with honey-bees, probably putting the ‘finishing touches’ to the honey back in their hives before the coming winter.

About 4.30pm, Barry and I lit a fire in the fireplace on The Children’s Plot, and we roasted homegrown potatoes while up at the metal shed, soup preparation was the order of the day.

Sairah, Sara and Matt has all brought home-made bread today, so this was excellent with the thick soup and piping hot potatoes.  Also, at this point I must just say that today, I actually did very little of the ‘fire work’.  This was almost totally down to Barry, and I must say, his potatoes really were superb.  Hells, he’d better not get too good at this, or I’ll be out of a job!

Hopefully more mid-week.


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