By
Kevin Craske (Area 9)
Well, I
hope that you have all read of the report of the AGM in the July 95 CRC
News, and for those of you who did not come I assure you it was your
loss. Something which was commented on however was Sandra's and my slide
presentation which was correctly reported as failing near the end due to
the control electronics packing up.
This is
very true but the comment 'like all complex electronics tends to be a
bit temperamental' I feel is not true. Electronics, even very complex
electronics, are very reliable and continue to carry out complex tasks
for extremely long periods of time without failing. Electronics are even
designed to detect where a temporary failure occurs and
correct
the error and very often electronics are employed to correct for errors
or short-comings of mechanical devices. I assure you that your domestic,
and even professional video recorders, would not even produce a picture
let alone a colour picture if it were not for complex electronics
overcoming and correcting the hopelessly inadequate mechanics. No!
Electronics fail when it is asked to perform outside its design
parameters.
Thus
when I looked at the situation again it was clear that a fault condition
was occurring which the correcting routines built in could not cope with
or correct. Also it seemed
to be random or possibly connected with the load. This led me to look at
the power supply as it seemed that the unit failed when the display was
at full brightness, and there it was. The power supply was only just
supplying the correct voltage, any slight hiccup and the supply was
below the design parameter and it switched off for a fraction of a
second. With the best will in the world, no electronics can correct an
error if it does not have sufficient power.
By
raising the supply volts by just ¼ of a volt all seems to have been
cured and just to prove it we completed a presentation which we
presented to the CRC some 4 years ago but this time controlled by the
new electronics, at a camera club at Holt. The show was rehearsed and
tweaked some 20 times before the performance and then to the audience
without one error. All seems to be cured.
Thus showing that if the unit is used within its design
parameters it can perform consistently.
And although I say it myself the electronics involved in the
system which I (and Dave Morrel) are working on is quite complex.
However
it would seem that someone is against us. It would seem that we are not
meant to get this system off the ground. Now that we have the
electronics sussed how else can we be stopped? No way you would say.
Well there is another way to stop us but this time it took a bit more
than ¼ of a volt. On her way to pick the children up from school,
Sandra was travelling in our 8 seater mini-bus on a main road when some
!!!!!! was daydreaming and did not stop at a cross-roads ploughing into
Sandra at 30mph into her side. The result - two cars a write off but
fortunately no serious injuries anywhere.
How does this stop our slide presentations? Our projectors were
still in the van from showing them at Holt.
4 projectors destroyed. Thus, just get it working to have it all
brought to a halt. One day !!!!!!!!!!!!!
Share
Your ideas - Where have all the thinkers gone?
By
Kevin Craske (Area 9)
I was
looking back at a few past newsletters and it occurred to me that of
late we lack the innotative streak in the club. Past newsletters had
ideas on how to build things , the latest money saving ideas or the
latest tweak in formula. It was good to see Roy Salmons work and his
progress and getting ideas by thinking of how to do things in other than
the conventional way. In fact, this leads straight into a suggestion for
Roy. In doing our AV's we wanted a large screen and quickly found out
that one about 9 ft wide would cost £300+. As I have not won the
lottery and no rich uncles what do we do? The way we do it is to use the
support system for paper backgrounds i.e. two extending tripods and an
extending 9ft pole. Ours came from Jessops. Then we use 9ft Colourama background paper Polar White. This works
beautifully at one third of the cost.
If the 'screen' gets damaged you just cut it off and use the next
bit. Also we have now
purchased a Lastolite background for portrait work and of course we
already have the support. So you see the supports are dual purpose,
projection screen or portrait background.
Now for a
plea for help from me. I have been working on a design for an accurate
digital thermometer and also a thermostat. My problem is with the probe.
The device which actually detects the temperature looks like a 'plastic'
transistor ( a small plastic cylindrical blob about 4mm in diameter and
5mm deep with 3 wires coming out at the end).
This needs
to be protected from the liquids which it needs to be immersed in but
conduct the heat of the liquid to it. It also has to be reasonably
robust. A problem is that I tried to put it in a small test tube and
seal the end with 'Araldite' but found that although the glue made a
good seal with the glass, plastic and the P.V.C. wire of the connection
and it was not affected by the chemicals, repeated changes in
temperature broke the seal. The glass expanded at a different rate to
the P.V.C. wire at a different rate to the 'Araldite'. The forces
produced just cracked the seal. Any thoughts? I also have an idea for an
all dancing E6 (or come to that any film process) automatic processor
but that is another story.