Friday, May 09, 2014
OK, so the buffer stop is now finished and installed. For the moment I've not PVA'd the gravel around it but that will happen the next time we get some sunny weather.
Inside, I've tried to waterproof the electronics as far as possible. The original casing from the solar light has been rebuilt around the circuit board and all the holes I can see are filled with Pound Shop epoxy resin. Soldered connections outside the casing are protected with heat shrink tubing.
With no moving parts inside, this ought to keep the light working for a long while. The weak link is the separate AA battery in the unit which relies on contact with its sprung connectors to work. I considered soldering it in (I think it's removable to conform with WEE regs for disposal) but have found in the past that you need flux on the contacts to get solder to stick and so that will just go green and cause the joints to fail anyway.
So, my hope is that if I keep as much moisture out as possible, I'll get a couple of years service from the unit. I think replacement will be possible, if not a 10 minute job.
One area I did initially get wrong was wiring the solar cell. With the polarities reversed, the circuit still charged and the light came on but it didn't switch off again in daylight. Obviously my error meant the transistor that handled this stuff wasn't working. A quick swap of the wires and in daylight the light is off, put your hand on the solar cell and it comes on. That's worth remembering for the future.