About Me

I've been taking things to bits, and making things ever since I can remember, starting with dismantling knackered alarm clocks and watches and helping my dad fix the car. Now I have a well-equipped workshop and have aquired lots of new skills, so I can make better stuff. When they first appeared, I became involved with personal computers, and these and developments in electronics have increased the scope of the things that I can do. Just recently retired, so O yes, now I can make all sorts of stuff.....

Sunday, 22 April 2012

Arduino and Home Easy problems

Whew!  Just spent the best part of a day and a half working out what was wrong with the Arduino-based  magic box that controls the lights and a bunch of other stuff in the house.

Its been working fine for a few months, but around a week ago it decided to either not turn stuff on, or turn it on and then forget to turn it off. Pretty poor show.  Most of the HE kit has its own switch in the room where it lives, but some can only be operated with the remote control which can be a bit of a pain.

I scribbled a quick bit of code for the arduino to flash the various pins that operate the remote control, and discovered that the one that turns things 'on' wasn't working.  The 'off' and 'unit' worked fine.

I started by checking the remote control which is hard wired to the arduino box with a length of CAT5 cable and a standard RJ45 plug - this lets me move the remote around the house using the CAT5 in the walls to get the best wireless signal for the HE stuff.  Opened up the remote, no obvious signs of wires hanging off.  Checked the voltage on the three pins that operate the control - two at 0v, but one at around 0.6v, no surprise that the odd one out was the 'on' connection.

I assumed that the remote was the most likely place for a fault, because I had to butcher it about a bit, so I replaced the opto-isolator for the 'on' button.  No joy.

So the control box had to come out of the rack, and be opened up.  I plugged the remote directly into the box and checked the resistance in the connections, all near enough zero as you'd expect.  From this I assumed that the problem probably lay in the arduino - a dead I/O pin probably - so I switched the connections on the processor and changed the code to use a different one.  Put it all back together, but no luck.

Out with the control box again, check everything again.  Still no joy.  While I had the bonnet up, I changed the 12 volt power supply that also lives in there - it was a switched mode supply previously and it had a lot of problems delivering 12 volts - sometimes it would drift up to 15 or 16 v, then other times it would drop to 4 or 5, playing havoc with my mailbox detector.  I binned the old PSU and replaced with a conventional transformer/rectifier/capacitor arrangement and bingo, 12.5 volts bang on the nose.

After replacing the original I/O pin and checking the software yet again, I concluded that either there was some strange fault in the arduino, or there was a cable fault.  Searched online for reasons for the arduino to play up without success, so I went back to the cabling.  This time I checked every single connection of every cable between the processor and the remote, including individual patch leads and the cables in the wall.

All still tested good, but then a fluke - I happened to move the end of one of the patch leads while the meter was still connected and lost the connection:  moved it a bit more and it came back.

Much happiness in the camp, the problem was an intermittent break in the patch lead (which is why it worked ok one day and not the next).  Cut up and binned the offending lead, then celebrated by flashing all the lights in the house on and off a few times without leaving my chair, which didn't go down too well with 'er indoors.

Saturday, 7 April 2012

Grandfather clock re-build

Well, its taken a solid two months of hard work, but the new case for the family grandfather clock is now completed. The pictures above and on the left shows the new one, and the one below shows how the old one looked before the re-furb.

The clock was originally built in around 1820, so he's nearly 200 years old, been in my family for six generations, and during that time he's taken a bit of a beating.

What's wrong with the old one?

Well, although the clock itself ran OK, the case was in a terrible state. Originally built with a cheap pine framework and veneered with mahogany, it must have looked fine to begin with but the years caused the veneer to split in lots of places and bits have fallen off, to be replaced by various of my ancestors with more enthusiasm than skill.

At some time the whole clock had obviously fallen face down, hopefully not when someone was walking past it, because the front of the case and the lower door had clear evidence of major full-frontal impact. The key for the lock for the lower door must have also been lost at some point, so a chunk had been gouged out of the case so that the door could be opened.

My mother told me that at one time it lived in a house with low ceilings, and it was too tall, so the owners simply dug a hole in the dirt floor and placed it in that. OK for a while, but the bottom foot of the case rotted away, and ended up being sawn off. I guess that was good in one way, as it meant that it would then fit under the low ceilings, but it meant that the weights had a shorter distance to fall and it would only run for around six days instead of the usual eight. My dad solved the problem by making a box out of some rough timber that he had lying around and balancing the clock slightly precariously on top of it.

Apart from the woodworm, last but not least, I found no less than 33 holes in the back panel of the case. These clocks are supposed to be screwed to the wall, but even allowing for numerous house moves I am mystified why it needed that many.

The clockwork bits

The mechanism ran fine, but it was absolutely filthy - my dad used to oil it with a mixture of engine oil and paraffin, liberally applied with an old paintbrush (that noise you can hear is the clock makers of this world screaming in pain), so the whole thing was covered in sticky black goo mixed with fluff and old spider's webs. I thought it best not to dismantle the old chap, so instead I carefully cleaned the whole thing with petrol and carburettor cleaner, and then lightly oiled all the shaft pivots with tiny drops of very thin oil (the same stuff used for my high speed engraver). One of the cords for the weights was a bit tattered, so I replaced it to avoid a 10 Kg lump of lead dropping through the floor in the middle of the night.

Time for the new case

I started with carefully measuring the old one, and working out how to make replicas of all the mouldings that had been used.

Next, with the assistance of my friend and grandson, Owen, we built a timber framework to provide a solid structure for the whole case. Not only did this give it strength, it also made sure that the structure was square and level. These clocks are picky about being level, so the base had adjustable feet concealed within so that we don't need to mess about packing the mechanism to make it level.

The frame was then sheathed in MDF. This may seem a bit non-traditional to the purists, but remember that these clocks were originally made from cheap materials and veneered with more expensive wood, and if the makers were building one today I expect they would have also used MDF. This material also has the advantage of being strong and dimensionally stable, so it should last a fair while.
The veneer used on the original was mahogany, but these days rocking horse poop is easier to get, so I used sapele for the various mouldings and other solid wood parts. Once the mouldings were made, using my trusty router and various modified cutters, the whole case was veneered and the mouldings fixed in place.

I re-used as much of the old case as possible - the brass finials on the front door; the lower door hinges; the lock for the lower door; the glass in the front door; the wooden pillars on the front, and a few other bits. The door which covers the clock face has concealed ball bearings to swing on in place of the rusty nails used on the originals, and a proper catch to hold it closed (the original was just jammed against the frame to keep it shut).

The whole thing was then given a double coating of mahogany stain to even out the colours of the various woods, and to make it look a little older, followed by several coats of danish oil and finished off with beeswax.

Placed it against the wall, used the hidden feet to bring the whole thing vertical in both planes, and screwed it to the wall. Placed the mechanism on the original seatboard, and hung the weights and pendulum, then adjusted the swing of the pendulum to give an even tick - if its uneven, the clock will only run for five minutes and then gives up.

I can hear it ticking reassuringly as I write this, and although its been a monumental job I'm very pleased with the result. Time to pack the tools away, clear all the dust out of the workshop, and start on the next project...