Browsing Posts published in September, 2010

10 Amps and rising.

Which is where my multimeter ‘bottoms out’.

If it has to read any more, it starts a mournful bleeping (…bleating?..), and the dislay starts flashing.  Yesterday it started doing this, and at first I didn’t quite know what to do.  Then it hit me!  Of course, I can simply read the voltage coming off the current-sensing amplifier!  Okay, a little maths will be required to work out what voltages correspond to what currents, but that’s no great shakes.

So yesterday, I modified the circuit to add the smoothing elements and the current sensing resistor is now after all these, and while it was much smoother to ride and the current didn’t ‘bounce’ quite as much on the meter read-out, there is still much work to do.

The new circuit.

The new circuit.

If you click a couple of times on the image to the left, you will see its subtly different to previous photos.

There is an added choke between the two FETs, the final diode has been moved, and there are two electrolytic capacitors stood up just to the left of the meter.

Oh, the programming board has disappeared as well!

I figured that since programming and trialing this board are now to separate operations, its no great shakes to do the programming sat here at my bench, then when the PIC is programmed, simply pop it into this board positioned by the bike.

Anyway, I’m expecting some parts for another job to arrive today, and when they do, I’ll have to work on them.  BUT, as soon as they’re out of the way, I’ll carry on with this.

All fun stuff!

Lights! Camera!…ACTION!!

Today marked LEAF’s first foray into the cinematic world, with a groudbreaking (…pun intended…) short movie (…just over 14 seconds, but there we go…) entitled ‘Charging’.


The plot really is a little weak, and I’m afraid the dialogue too.

In fact, I muted the sound to prevent the viewer with a delicate constitution having to hear the sounds of a harsh whip being liberally applied to the poor cyclist in an effort to get them to cycle faster.  How we suffer for our art.

Seriously, what you can see from this shaky clip is the yellow multimeter on the left measuring current.  The read-out is in Amps.  When the circuit thinks its hit a peak, the red light briefly comes on.  As you can see from the meter readings, they are considerably higher than just the other day -nearly 8 Amps briefly.  This is good.

What’s not quite so good is that the two chopping FET’s did get rather warm.

This is not a problem at all -I’ll just whack more of them in parallel, thereby distributing the current and lowering the heat dissipation.  No problem.

So tonight, I plan to ‘smooth’ out the meter’s erratic measurements by adding a smoothing circuit and also monitoring the current after it has been smoothed.

This smoothing circuit will take the form of a chunky diode, a chunky inductor and an even chunkier electrolytic capacitor, all ‘rescued’ for the seeming dozens of old computer power supplies I have here, all thanks to our good friends at Taplin Computers and their scrap bin.

With this in place -along with another couple of the chopping FET’s, the quest will continue for more current!

More soon.

More painting and artwork. 25/09/10

Tomorrow marks the annual ‘Allotment Soup’ open day, this year held down in Rivelin Valley on the allotments there.

There’ll be loads going on, and we decided to take our growing scarecrow ‘family’, and a load of painted cardboard ‘gardening paraphenalia’, so artfully painted by our ‘Plot Kids’.

The owl and the butterfly.

The owl and the butterfly.

Here, you can see an owl and a beautifully painted butterfly.

A beetle and a ladybird.

A beetle and a ladybird.

To the left here are more painted cardboard cut-outs.  This time a beetle and a ladybird.  These are ‘sat’ on the fence leading into the childrens’ plot by the main entrance.

Soon, yet more artwork seemed to ‘magically’ appear in the shape of gardening tools, a spade and a couple of forks, a watering can, and here’s Jo holding the butterfly from the photo above.

Jo and the gardening tools.

Jo and the gardening tools.

Of course, I couldn’t finish this entry without reference to a cat!

The black cat.

The black cat.

Here is today’s splendid effort:-

Now Mitzi, our Plot Cat is a grey tabby, and yet this one is black.

My cat is black.

Are people trying to say that I should bring Young Alfie down with me one Saturday?

Are they ready for the kind of chaos this would cause?  I think probably not, so for the time being, he’ll continue to be the ‘Local Terror’ round here, thankyou very much!

All action. 25/09/10

Like most Saturdays, today started off in a quiet kind of way, the way a Saturday should start off, and then, well, things just got madder and madder.

But all in the nicest possible way.

The lower path that Barry & Nick re-woodchipped.

The lower path that Barry & Nick re-woodchipped.

Of course, Diane arrived for ten, but when I arrived for about eleven, no-one had yet turned up.  We weren’t worried, and sure enough, no sooner had we sat down for a first cup of tea and chat about what was to be done, Barry, Sairah and little Adam turned up bearing large amounts of food for us to share.

We all shared tea and caught up on the week, then Barry and I decided that as the fire was due to be lit at four, we’d start re-woodchipping a couple of the paths.

Just a few days ago, Diane had supervised the re-chipping of the area where we eat and congregate during the week, but there had been a couple of complaints of slippy paths and Tim, who uses a mobility scooter had remarked that a couple of corners were pretty treacherous.

Like all jobs seem to do, it kind of grew.  I had just intended to scrape up a load of mud on one of the treacherous corners, but then realised that more scraping and woodchipping needed doing.

In the end, in just over two hours, we scraped and re-woodchipped the ‘top’ main path from the main driveway to the metal shed, then moved onto the ‘lower’ path that leads in the same direction.  This path needed much more taking off, so was much more time consuming -and back-breaking!

All the ‘mulched down’ scrapings were placed in a long pile by the main entrance.  These will be left for another few months longer to rot down further and then used as a mulch for beds we prepare, probably in spring next year.

We were so engrossed in our work, we hardly noticed as more and more volunteers arrived.

Soon, nearly every part of the LEAF plots was being used for a different activity.

Earlier, we had set up two of the gazebos by the entrance drive ready for Jo and the children who were putting the finishing touches to many cardboard cut-out figures, animals, a shed!, and hand tools. (See separate Blog entry.)

Meanwhile, Gary, Tina and Pam carried on with the onion-stringing.

Stringing more onions.

Stringing more onions.

Here, you can see the three of them, busy at work.

More onions on strings.

More onions on strings.

And here on the right, you can see their finished work.

Tonight, these will hopefully have been hung from the rafters in the top shed, and luckily, there’s plenty of space for plenty more, because we have loads of not only onions, but a huge amount of garlic to string up as well.

By hanging them in this way, we are hoping to keep as many as possible for our own use in soups and stews on a Saturday.

By four o’clock it was time to light the fire.  Barry and I had selected a load of home grown potatoes -small ones- for the fire and Sara duly wrapped them all in tinfoil and placed them in tins ready for roasting.

While we busied themselves roasting the potatoes, up by the metal shed the ingedients for a stir fry were being prepared and presented all in separate bowls.  This would give people the opportunity to select just what they wanted to stir fry, then hand them in a bowl to Barry (…who in a previous life was a chef…), so he could quickly whack them into the hot wok and quickly fry them off.

This seemed to work very well, and soon everyone was tucking into large portions of stir fry, hot roasted potatoes and quite a few different home-made bread loaves that various volunteers had brought.

An excellent sufficiency!

All too soon it was time for me to leave.  I had to get back here to do this, but first and foremost, I had to get a shower and change my clothes.  Firestarting really is a lot of fun, especially for ‘boys’, but it doesn’t half make you smell afterwards!

String ‘em up! 24/09/10

No, we’re not talking about ‘baddies’ or other random miscreants.

We’re talking onions!

Gary and strung red onions.

Gary and strung red onions.

To the right here is a shot taken today of Gary, one of our most hard-working ‘Plotters’ proudly showing off a string of red onions he and Tina made just the other day.

And marvellous fun they had too!

He tells me that this Saturday they will be doing more -and they need to!  We had such a good crop of various different varieties of onions this year that we desperately need the room.  Rather than being stored in the bulky red bread trays, these and many more besides will be hung in the top shed from the rafters allowing them to dry further and take up very little room in the process.

They also need to string up all the garlic as well!

Last thoughts on the day.

Its getting a little late, so I shan’t be long in this, but these last few days really have been quite a big deal, both for me and for ‘The Project’, and I really feel that now in this ‘quiet time’, its maybe a chance to reflect on just what’s been achieved.

In just over a week, the project has moved forward in leaps and bounds.  Just ten days ago, I was still scratching my head trying to get it round the idea of ‘dummy loads’ and all other manner of problems.  Now, as I’m sat here, I simply turn behind me to see the bike with its generator attached, and attached to that is the ‘shiny new’ electronics board that will measure not only voltage, but current flowing into the battery as well.  And now, not only can I monitor these things, but I can control them as well! By simply changing just a few bytes of code, I can make it do whatever I want!  You want a gentle start?  No problem!  You want an Alpine mountain climb?  Easy!

…Dave came round this afternoon to see what I’d been up to, and aside from being pretty impressed that I’ve still ‘got the touch’ when it comes to building things, he’s anxious that I just ‘put the finishing touches’ to the circuit so that next week, he can start in earnest with the coding.

So tomorrow, I’m just going to put some strain-relief on the input and output cables, I’m going to change over the polarity of one of the plugs and sockets so nothing can be plugged in incorrectly, then build a little circuit and mount it on the board to smooth the power coming from the chopping FET’s in exactly the same way as a computer power supply works.  BIG diodes, BIG coil and a BIG smoothing capacitor.  Easy stuff that will take no more than an hour or so.

THEN I/we have to design the ‘user interface’.

Now this will be the really, really fun bit.

Of course, I haven’t forgotten the ‘JBM’ and ‘JCBM’ buttons.  What? You forgot?  Pah!

‘JBM’ = ‘Jon’s Biscuit Meter’

‘JCBM’ = ‘Jon’s Chocolate Biscuit Meter’

If you recall, press either of these two buttons, and you have to put so many Joules into the battery by pedalling faster for a given period of time.  Obviously the ‘JCBM’ requires quite a bit more work for the lamp to light to say you can have one!

Other features will be two buttons -one for ‘Less!’ and one for ‘More!’ to decrease and increase the loading on the back wheel.  Of course, if you press the ‘More!’ button, for each turn of the pedals you put more into the batteries, so your calorie count will go up accordingly.

Another idea er, ‘borrowed’ from gymnasiums up and down the land is that of a ‘hill profile’ so you will be able to see on the display in front of you when you are coming up to a ‘steep hill’ or a ‘gentle pedal’.  A timer, perhaps?  A ‘Watt Meter’ (…or ‘Calories Meter’…)?  A distance travelled/mileometer? Aah, the choices!

A good way down the line will be when each bike ‘remembers’ each rider because they’ll have an ‘iButton’ attached to their keyring.  The user will simply start pedalling to turn the bike ‘on’, then touch the iButton into a little round receptical -like they have on some bar tills, and it’ll know who they are.  Eventually, each bike will be linked in with the central ‘mother’ unit, and this will have stored each user’s ‘profile’ and their history.

I mentioned this almost as a ‘throw away’ when I gave a few minutes talk at the excellent ‘Grow Sheffield’ AGM a few months ago (…see the new ‘Links’ section at the top of the page for their address…), and there were several ‘health professionals’ in the audience who have dealings with the public and the growing national problem of overweight and even obesity.

Well, their eyes lit up at this, and there were quite a few questions afterwards as to how this would be achieved, and exactly what it would involve.

Obviously, an awful lot more work needs to be done yet, but I can only see the outcome as being a win:win situation:-

People want to come regularly to use our bikes, under cover(!) and in the fresh air to lose a few pounds, then great!  We’ll keep the energy they ‘burn off’ to power our lights and heat our water!  Who knows, they may even want to stay afterwards to pull some weeds or do some watering!

Anyway, that little scenario is quite a few months off yet, so lest we get carried into ‘Fantasy Land’, when I’ve got the circuitboard neatened up and ‘bullet-proof’, Dave will be writing some pretty ‘basic’ code just to get us up and running. That’ll be when we can let our imaginations out to play.

So, Dear Reader:  Is there anything you’d like to see on the bikes?

Sensible answers please to nick(AT)leafsheffield(dot)org(dot)uk!

-That was just to try and stop ‘web robots’ from getting my e-mail address.

Last Saturday we had a lovely creative day at LEAF. I arrived late in the day as usual, and to my delight Jo had organised a fantastic painting activity for the children, and I was very impressed with the larger-than-life self portraits they had painted.

Jo putting the finishing touches to Lisa's fantastic colourful self portrait

Jo putting the finishing touches to Lisa's fantastic colourful self portrait

Jo and Matt were busy constructing a shed out of cardboard, and were constantly interrupted by children trying to climb in and out of the shed whilst it was still under construction! You just can’t beat a cardboard box!

Matt and Jo working on the fantastic cardboard shed

Matt and Jo working on the fantastic cardboard shed, a hit with the children of all ages!

I got stuck in and started to make some large cardboard garden forks and spades –  all of these things are going to be part of LEAF’s creative contribution to Allotment Soup at Rivelin allotments this weekend. We will also be taking some of our fantastic scarecrows so hope to see you there!

Heeley City Farm

Just a quick post to share a few photos I took at the Heeley City Farm Fair last Sunday. It was great to have a look around the site, and everything growing looked very green and healthy.

Lovely veg bedsFruit trees & Polytunnel
However my favourite thing was the hairy, bristley, snuffly and rather smelly pig who was absolutely in his element with a snout full of mud!Pig enjoying snortling in the mud!

Independence Day.

Just a few minutes ago, here at ‘Wardian Towers’, we achieved just this.  Total Independence.



Last night after that feverish Blog entry, I carried on and added the ‘7805’ voltage regulator I mentioned.

Double click on the photo to the left and you’ll see it sat on the top left of the board.  Yes, its got a heatsink on, but that was only out of force of habit.  Measurements show that its taking much less than 10 milliamps when running, so it really wasn’t needed.

Once again, I got on the bike, but this time there was none of the ‘fearfulness’ of last night’s adventures.  I knew it would fire up!

And fire up it did, just the same as last night.  First the top-most green LED next to that big, cute electrolytic capacitor below the heatsink, then with a slight increase in speed, the lower green one, just above the other new electrolytic that’s above the empty 40 pin socket.  We were charging!

If you look at this photo, as well as that new heatsink for the regulator and the smoothing electrolytics, you’ll hopefully notice the lack of any wires going to the programming board on the right.  It’s not plugged into the board on the right in any way.  No power and no programming lines.

Okay, it means I have to take the PIC out every time I want to program it, but this is no big bother.

…So now the board is fully ‘capped-up’ with those two electrolytics and a much smaller ‘de-coupler’ to take out any little nasty ‘spikes’ that may appear, and I feel much better, much safer because of this.  It means the circuit is nigh-on ‘bomb-proof’ -at least electrically.  If its to be ‘bomb-proof’ mechanically, then I’d put it in a box, but as I need to be able to get to the PIC to be able to program it, thats not really an issue yet.

So, the circuit is now fully independent of the mains, and I have the laptop to program it with, so now I can use it wherever I like!

Anyway, a quick shower, then off for the morning’s session at LEAF.

Will there be massive praise when I arrive?  Will they have the red carpets out?

I sincerely hope not!  Though I imagine the line; “So why haven’t you brought it to show us??!!” may well be uttered at some point.

No worries.  I’m sure the kettle will be on!

Momentous. 22/09/10

Ladies and Gentlemen, tonight something extraordinary happened.

At precisely 8.15pm BST, I sat on the bike, said a little prayer to whichever Gods may have been listening, and started pedalling.

Quite slowly at first, all the time looking for the tell-tale plumes of blue smoke and all the while sniffing the air for that unmistakeable smell of frying silicon.


So I pedalled a little faster…

…And the first green LED lit.  “…Huston, we have a green light on the board.  Ignition set for ‘Go!’…”

My heart was pounding, my stomach somewhere up near my throat.  Still no smoke or burning smell.

I pedalled a little faster still…

…And the other green LED to tell me that charge was being transferred first flickered, then lit properly. “…We have main lift off.  All engines running at 110%…”

I looked over at my multimeter, wired in series with the battery and set to read current.

It flickered, numbers rapidly changing.

So, I pedalled faster still, and kept that speed, and sure enough, both LED’s were still lit, and the meter had settled down to read a steady 0.5 A.  “Huston, we have achieved escape velocity…”

Okay, not earth-shattering numbers here, but its a start!

I had purposefully set the PWM width (…that’s how much I’m putting into the battery…) to be very, very slim, so this was entirely expected.

SO tomorrow, I’m going to pop down to Maplin’s first thing to get a ‘7805’ 5 volt regulator and a few de-coupling capacitors.  When properly wired up, this will mean that the unit is entirely free-standing.  No mains required.  The 7805 will power the little PIC processor and associated circuitry, and the power for that will come from the battery -it certainly won’t hurt any as it only takes a few milliamps.

This will mean that if all goes according to plan (…HA!..), I can take the bike, the circuit board and some lights down to LEAF on Saturday!  Volunteers will be able to ‘have a go’ at charging the battery, and we’ll be able to have lights to see by.


Just the other day, I bought a really ancient but otherwise fully working laptop in really gorgeous condition from ‘Taplin Computers’.  This will be used to show photos that we’ve taken while we’re down on The Plots.  The ‘synchronous’ part is that unlike many newer laptops, this one has a nine-pin serial port on it.   With a little initial ‘setting up’, this will connect straight into my little PIC programming board.  This means I’ll be able to make code changes on the site without having to come all the way back here to my main computer.

10.22pm News:

Just checked Maplin’s online, and they’re completely out of stock of ‘7805’ voltage regulators.

However, a good rummage through my parts inventory, and I’ve got a brand new one!

So, my mistress Lady Sleep will probably be a long time coming tonight.  I’d better get to work now then…

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