Vibro Morse keyer

The keen-eyed amongst you will have noticed that it has been bodged together with bits from a hoarder's dream. There is a proliferation of the knurled brass screw tops that used to adorn the 4 1/2 volt Ever Ready batteries (probably 45 years in the junk box, bound to be useful someday!), the two contact pillars are fashioned from the pins of round-pin mains plugs, and the connections are to two Binding Posts of 1930s vintage.

Appropriate, perhaps, for a replica of a machine that was patented just over

100 years ago?

Although the construction looks a bit chunky, the working bits are in fact the same dimensions as the Vibroplex from which it was cribbed.

The base is bigger because it was a piece of scrap ally in the junk box.

The marble has to be large to match the base.

I have long wanted a Morse Key where the operating lever was at desk level, and I have achieved this with the right-angled drop down,

For a rather unusual use:-

(OK, I cannot deny your curiosity. I want to graft selected seedling alders onto "Adult" trees. There is no problem about the woodwork, but they just don't "take". Some people graft alder cultivars onto potted trees which they lay across a hot pipe (How hot? I don't know yet), and then the graft "takes". But you can't do that with rooted trees in the outdoors. So I used 24 volt AC from a transformer, feeding 2 KOhm 2 watt resistors (about the same diameter as the alder twigs) taped to the twig, wrapped round with 10 cms of bubblewrap (which can't get waterlogged, about 3 turns) which gives a temperature about 10°C above ambient. That seems just cosy. But it didn't work! The grafts died!

Why not? 2 possibilities have been suggested to me:-

1) The heat is too localised.

2) Voltage gradients are set up on the twigs which kill them.

I am doubtful about both, but I must try them. One of the problems is weight; these twigs are 2-3mm in diameter at the end of long branches and there is limit to what they will bear.

One possibility is to tape the resistor to one side of a sachet of some liquid, any liquid, so long as it's not too expensive, and tape the other side to the graft. Possible!

But rather better it seems to me, is to use that kind of soft sheet metal that toothpaste tubes used to be made of. I would simply wrap one turn round the resistor and the second turn the other way round round the twig, making a kind of figure of eight (8). That would both supply uniform heat to the graft and shield it from electrical fields.

But where do you get such soft sheet metal? Does any kind of toothpaste still come in it? Where can I get it? What is it CALLED? You can't ask for something which you don't know the name of!

Shooting in the dark!

Michael Bell

Could get some lead flashing and a set of rolls to roll it thinner or even beat it thinner with a planishing hammer. Alternatively, you could treat yourself to a few bottles of decent wine. Check the cover over the bottle end before purchase, since you don't want the cheap plastic stuff :-)

Does the air-graft actually need to be heated at all?

Mark Rand RTFM

What I have actually done is use cut-up disposable "aluminium" pie trays from the supermarket. It's not as thick as "card" but it's thicker than ordinary paper. It folds and then holds its shape in a handy way. It will certainly shield the graft from the voltage gradients and it really ought to distribute the heat, about 0.3 watt's worth, 10 °C.

That is the question to be answered. Others say that it works, but heating it electrically, I couldn't make it work. So, on un-grafted, normal branches,I am investigating possible causes:-

1) That uneven distribution of the heat is the problem. I am testing that as described above by using thin sheet metal to distribute the heat. 2) That the voltage gradients are the problem. At first I was very sceptical of this - 24 volts is not a killer voltage!, but now I have come round to thinking it is quite likely. I am testing it in 2 ways:-

a) Simply taping a wire to the branch. _______________________ ~_______________________

to produce voltage gradients across the branch

b) Taping a wire to the branch, but cutting back one of the conductors. __________________________________ ~______________

to produce a voltage gradient along the branch.

Let's hope a result appears before the branches loose their leaves for autumn anyway.

Michael Bell

Michael,

Lead foil. :-)

See the top of this web page for products.

Jim.

Thank you. If the stuff I have used is unsatisfactory, I'll use this, rather more expensive!

Michael

If you have stone masons in the area then they often use a very thin sheet zinc, IIRC for templates. My local engineering supplier Avery Knight and Bowlers in Bath stocks it. It is about 0.5mm thick and easy to work.

Thank you for this. It will go onto my list of possible solutions.

Michael Bell

Michael,

Thin lead foil is also used in fly tying for angling so you might find smaller quantities at proportionally less cost if you dig around on Google.

Jim.

Thank you. It's amazing the variety of sources that have been suggested on other groups, Euthymol toothpaste, Tomato puree, Kavli cheese tubes... Seek and ye will find indeed! Your suggestion will go onto the list. Thank you.

Michael Bell

Ouch that's expensive.

Any reason you can't use lead roofing flashing? Code 3 (3 lb/sq ft) should do, about £30-40 for 6m by 150mm. Bit thicker than foil, but is there any harm in that?

I think copper would be a mistake here, possibly toxic.

Can you use DC rather than AC? If you use shielded cable with the shield grounded you shouldn't have much in the way of electric or EM fields near the plant.

Weight may be a problem. These are thin branches at a long reach.

I could use DC. Then does it have to be perfectly smoothed? Where do you stop? Before I explore these avenues I'll see if I can make what I have work.

Michael Bell