I think I mentioned that today I had another ‘meeting’.

Well, in actual fact it was up at The Royal Hallamshire Hospital.

Don’t worry, nothing serious, just to go for the fitting of a hearing aid.

So why do I mention this?  Well, Dear Reader, directly opposite the hospital on Glossop Road is a shop called “Parmount Medical”.  Its used by junior doctors for all kinds of things -most notably a dizzying array of stethoscopes, but of interest to me because it is the only shop in Sheffield where I know they stock scalpels.

Not for cutting up volunteers you understand, but very useful for the kind of electronics I’m having to do; namely pratty and fiddly.

I was a few minutes early for my appointment, so strolled in to be met by a very nice lady who listened quite patiently to my tales of woe in trying to find something small enough to cut between circuit tracks on Veroboard, so she then proceeded to show me quite a range of suitable scalpels.

Toys.

Toys.

In the end I chose a number 3 in surgical steel.  I could have gone for the cheaper option of disposable, throw-away, plastic ones, but as I want this to last, and its not the ‘LEAF Ethos’ to be disposable, it seemed the best way to go.

After the sale (£3.85 for the handle and five blades.), I mentioned that I was looking for equally small forceps.

Well, her face fell, and when she showed me a catalouge, I could see why.  There was a pair of ultra-fine tweezers (…but still not as fine as the ones I had at DCS…) for nearly £200.00!

To make up for this, she GAVE me a pair of use-once (…for medical use, but fortunately ‘use many’, many times for electronics!..) tweezers AND a pair of forceps.  When I tried to pay her, she refused, saying that as they were out of their sterile packaging, she would have to throw them away anyway.

The circuit board as it currently stands.

The circuit board as it currently stands.

Effusive thanks due!

So, to the right here is the circuit board as it stands now.

Right in the centre is the green LED I mentioned last night that will simply show when a preset current is flowing into the batteries.  Quite what that current will be, well, we’ll have to see, but at least the indicator’s there.

You can see the two empty chip sockets; the big one on the left hand side and the smaller one just to the right and above the new LED.

When I first power up this board -of course making sure there are no nasty voltages to be had, then I’ll put a PIC16F684 in the smaller socket.  For now, the bigger one is being left empty.

Just below the empty 14 pin socket there is a white ‘square’.  This is the stood-up high-current 1 Ohm resistor used for current measurement.  In the final version, this will be replaced with a group of 10 0.1 Ohm resistors that will be able to handle the much higher current that will come from a cyclist.  Just below that is my ‘bodged’ effort turning a ‘SOIC’ chip into something that will fit into a standard DIL socket.  And it works well, too!

Anyway, I’d better crack on…