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||How do you create a wind turbine for
electricity if their is no "wind" ?
(See bottom of page for suggested answers)
for crossword No 1
(answers at bottom of this page)
|A good friend of mine
presented me with a cheap radio controlled boat to “have a look at”.
He demonstrated the problem to me…
On activating the transmitter, the boat’s propeller would spin a couple of times and then stop.
He was convinced that the battery pack was at fault and he was thoroughly annoyed with it, as it had only been used twice.
I was convinced however, upon seeing the unit, that the problem was a little more complicated than that.
I started to tackle the boat the next day.
The battery pack had water damage and the connector assembly had corroded quite badly.
It was obvious that it had had a good dunking in salt water.
I measured the battery voltage and found it to be correct, and it also seemed fully charged.
As it was capable of delivering plenty of power, the fault must lay (I thought) in the boat itself.
I disassembled the boat and examined everything.
The designers had gone to a lot of trouble to waterproof everything.
The electronics were encased in their own little waterproof housing.
No sign of any water damage to anything inside the boat. So what was wrong?
I then thought about the transmitter.
Was there a fault in it ?.... I opened it up and attached the C.R.O. to the aerial.
I saw a very brief burst of R.F. and then nothing.
Maybe this was why the boat didn’t respond!
On further examination, the transmitter module appeared to be water damaged too.
I tried giving it a clean with alcohol and hoped that the fine tracks on the circuit board were still O.K.
I couldn’t tell if the surface mount components had come through the ordeal O.K.…
Doing micro-surgery on it did not look at all pleasant!
Fortunately it now seemed to work, with coded bursts of R.F. clearly evident when the rudder and throttle controls were operated. The boat responded properly when switched on.
Just the battery-pack connector to sort out now!
Oh yeah! It’s never that easy!
I was about to fit a new connector when the positive wire fell off the battery-pack. Darn! (or some such words)
I was going to have to rebuild the battery-pack!
It was duly disassembled and the whole lot cleaned up…. Yes the water had got right inside it of course!
The positive terminal was originally covered in heat-shrink tubing and when it was removed, another potential fault was revealed.
There was no solder on it!
The wire had been tinned but that was all.
The heat-shrink tubing was the only thing keeping the wire in contact with the terminal!
Why do my “simple” repair jobs turn out to be Pandora’s boxes?
I HAVE got better things to do!
Anyway. While I was at it, I decided to check the negative terminal as well.
This time there was a properly soldered connection to the wire.
There is however, a peculiar problem with the negative connections in NiCad battery packs.
The dreaded “black wire” syndrome, and this pack was no exception.
I have noticed it a lot over the years with NiCad or the newer NiMHD battery packs.
Every strand of wire in the negative lead takes on a black coating, presumably some form of copper oxide.
It is impossible to solder to and very hard to scrape away, and it usually goes the entire length of the wire, whether it is just a few centimetres or a whole metre in length!
The only solution is to replace the lead with a new one.
I would be very interested to know why this happens….. And why only the negative lead?
Once the battery pack wiring had been fixed, the pack was wrapped in plastic and electrical tape.
I then looked at the connectors.
I wanted to waterproof them, but found there wasn’t enough space to do so and fit the battery in the area available.
The “plastic pilot” wouldn’t sit in his seat properly!
I decided to hard-wire the battery pack in place and fit a waterproof connector on the boat.
The battery charger could then simply be plugged into the boat when necessary.
A green “charging” LED then completed the repair.
So my friend took his boat back home and his grandson was very pleased to have his favourite Christmas toy back!
I suggested that he fit the transmitter with a lanyard so it stays around the user’s neck and not in the water!
The boat could be finished with some neutral cure silicone seal around the battery pack.
My friend could take care of that part himself.
Till next time.
this article belong to "Rick's
Workbench" in Tasmania
: We do not recommend attempting mains powered projects or
The articles from "Rick's Workbench" are for entertaining reading only.
There has been a solution to
this problem in warmer
climates for quite some time.