How can you "drive" a wind clock?

[Eugene]

Some years ago at the National Trust property, Coleton Fishacre, along with some interior decorating and garden design ideas which we pinched, I saw my first ever wind clock and decided one day I'd make one. Next year I'm doing a major refurb. on the snug in our cottage and this will be my big chance.

Here is a snap of it in the library ....



How cool is that?

Superimposed on a painted map of the coast where the house sits is a dial showing the wind direction. The wind vane on the roof is connected mechanically to the compass dial indicator; I think its steel rods and bevel gears running down the inside of the chimney but I'm not too sure after all this time. Anyway that's not for us, we want some form a device that attached to an exterior wind vane can "drive" the compass needle with a bit of damping. I guess this means some sort of electric signal transmitted to "the driver" but I'm clueless on electronics.

So there you go fellers, what can you come up with that an electrical duffer might be able to cobble together, or indeed can you see any other method?

Thanks

Eug

[awemawson]

That's what synchros  and resolvers were designed for. WW2 technology but they work!

[Bluechip]

That's what synchros  and resolvers were designed for. WW2 technology but they work!

Very true, Andrew. Remember those from work a long time ago. Not seen them in Poundland recently though ... 

OK Eugene ... There was a Weather Station in Practical Electronics [ I think ] round about 1980-ish which had one.

It would be easy to implement one now with a Gray code transmitter disc [ IIRC it was 5-bit giving 16 points ] and a uController / stepper for the display wotsit but that's not much good for an ' electrical duffer' though ...

If you wanted use 2 uControllers, one at the top end to send serial data to t'other. Cuts down on the cabling  ... make it as complicated as you like ..

One here with LEDs :

http://www.instructables.com/id/LED-wind-indicator/

I can't think of any really simple electrical way to do it other than hurl vast sums of money at it with S/R set up.



Bit of a bugger ain't it ???


Dave

[vtsteam]

Maybe an R/C servo, and a servo tester.  You'll have to open them and maybe play with limits contacts to get 360 degrees of movement. Same with the pot in the servo tester.

Try Hobbyking for low prices. Make the servo a big one, not for power, but so it's easier to work on.

Maybe Simon Heslop can help you out, now he's familiar with servo testers in his electric bike build.

R/C sailboat winch servos might allow 360 degree movement out o the box, not sure.

Anyway this would potentially be a very cheap system, though requiring tinkering a little to get full movement.


or.......... maybe a scrapped antenna rotator?


ps. could drive you a little nutty in gusty conditions? Might want to think about something that does averaging, well damped.


re. synchro motors -- Andrew, Bluechip, would old electric clock or other synchronous motors be able to be convinced into a pair, or is the word "synchronous" not really applicable to synchro motor pairs? Or what about stepper motors -- can they be fooled into thinking they are synchros?

[John Hill]

The required  'synchros' are magslips and quite different to any regular synchronous motor, they are also quite different to what model aircraft folks know as servos.

I have some idea of how they work and I have a few in the shed (but that is in New Zealand!).

This is Madmodders and we should be able to design and make our own!

Anyway, this is how they work:  There are two devices that are similar  motor like devices which have a three phase field and a single phase on the armature.  Both ends are the same,  the three phases at one end are connected via 3 wires to the three phases at the other end.  Both armatures are connected to an AC current.

The AC current in the armatures induces  AC currents in the field windings phased according to the position of the armature.  If they are free to move the two armatures will take up a position were the 3 phases at one end are in phase with the 3 phases at the other end.  Therefore if you move one and the other is free to move it too will move the same amount.

Now then,  Madmodder hat on!   
A common or garden car alternator has a 3 phase stator and a single phase armature.  In the alternator the armature is called the field.  At first glance it would appear that two alternators could be used as a magslip link and drive the wind direction device.

Not really electronics,  more electrics.

So,  how to test the idea.  Get two alternators that are similar.  Get a low voltage AC transformer,  those 12 volt lighting transformers might be good enough.

Open the alternators and snip out the diode bridge  so that you have 6 wires coming from the stator windings.  Use you meter to identify  the ends that are connected to each coil then connect all three coils together in series, there will be 3 joins required and these joins are the 3 phase connections that you connect to the similar 3 phase points on the other alternator.

Get rid of the voltage regulator if it is internal and find the two wires that are connected to the rotor via carbon brushes (these will likely be labelled 'F' for field),  connect the two rotors together in series and connect to your 12 volt transformer along with a 12 volt light socket all in series.   

THAT'S  IT!

Put a 12 volt globe in the light socket and turn on the power to your 12 volt transformer.  Hopefully there will be a bit of buzzing and the light will be lit but not full brilliance.  Turn one shaft and see if the other one moves, or at least shows any tendency to move.

Report your results.


BTW,  these devices were invented in WWI and used in battleship range finders and gun control equipment.  They wanted very low friction and maximum sensitivity and resolution so did away with the troublesome slip rings and brushes and replaced them with magnetic connections which they called magnetic slip rings, hence the name 'magslip'.  They are called 'synchros' in the US.

There are a couple of reasons why this idea might not work and one of them is that the alternator may have too many poles, but I dont really know so hopefully some keen type will try the above experiment!

[awemawson]

Or you could go to Anchor Supplies in Nottingham by the Trent Bridge ground and buy a pair of the real things. They had boxes of them when I was last there 

[lordedmond]

You got it John

We used them on the base exchange units at the iron works to tel the operators when to add charge

Google the name selsyn

They did not have a armature but a two pole electro magnet fed by slip rings , with dc both units the stators were wound for three phase these were conected to each unit but with no other conection or power the only power was to the rotors of each unit

But with some tricky wiring the sender unit could be powered as was the case in our application the weight was wound up prior to a charge dump else you would bury the weight

Good units but I would bet they are expensive


As mentioned rc servos could be repurposed

Stuart

[John Hill]

Or you could go to Anchor Supplies in Nottingham by the Trent Bridge ground and buy a pair of the real things. They had boxes of them when I was last there 

There were a lot of them around in things like radar sets,  all manner of military stuff and anywhere in industry where they needed a remote indicator of the angular position of a shaft.  Ham radio chaps used to buy them to remotely indicate the position of movable beam antennas etc.  They were also used in wind direction indicators which is where mine came from!

The challenge with a wind direction indicator is finding something that can go full 360 degrees and more.

[Bluechip]

Or you could go to Anchor Supplies in Nottingham by the Trent Bridge ground and buy a pair of the real things. They had boxes of them when I was last there 

They've got a place about 5 mins drive from me at Ripley.

Last time I went there some 4 years ago - ish, there was not much in there compared with ages past.

Although looking now at their stock, this was of interest ...

http://www.anchorsupplies.com/last-few/queens-royal-standard-in-residence-flag-15ft-x-24ft.html

Something for you to fly over your place ??? Impress the neighbours etc. ??

Dave

[awemawson]

You'll need that Standard when the Queen comes to stay 

I have fond memories of the Ripley yard - bought some very useful stuff there over the years When I used to travel the country a fair bit, I'd divert over the Pennines from head office in Manchester, come down the M1 and pick up Ripley, then through Nottingham to Trent Bridge, then out the bottom of Nottingham by the Ratcliffe coal fired power station.

[BillTodd]

I've seen this done in a couple of clever ways:

a) I used to repair and fit Yacht electronics and one make Mariner used a neat & simple 3ph potentiometer linked to a small 3ph motor in the head unit (see pic below). The pot, made by Penny&Giles, was the better part of £100 back then

b) Saw this idea in an electronics mag's and thought it worth keeping.
The idea is that the wind speed vane, scans the direction vane producing two pulses . one pulse produced by the speed vane is counted to measure speed and it is also used as a reference to  time the direction pulse . measuring the delay between pulse thus gives direction.

[edit] thinking about it, the pot may have been configure as below.

Bill

[lordedmond]

I have seen systems in place at some old hotels we have stayed in it seemed to be very small unit they were old so no new finagled stuff

They were both at golf related ones Turnberry and Gleneagles ,but  have seen them in many more

Or you could take the easy way out
http://www.amazon.co.uk/Replacement-Direction-Sensor-Weather-Statoions/dp/B00FQGV8RM/ref=sr_1_2?ie=UTF8&qid=1408614085&sr=8-2&keywords=wind+direction


Stuart

[BillTodd]

Video of the mariner system working sort of - I think the pot and/or motor  is faulty (which is why i have it in the spares draw)

     

Bill

[awemawson]

Cheap synchros on ebay:

http://www.ebay.co.uk/itm/CLIFTON-PRECISION-TANDEM-SYNCHRO-400Hz-UTTH-11-RS-/120869094002?pt=LH_DefaultDomain_0&hash=item1c245c0272

[Eugene]

My head hurts! 

Thanks for all the responses guys, lots of things to ponder over, but Bills wee demo and the link provided by Andrew look pretty promising.

Andrew, would two of the doo dahs in the link do the job (ie one drive t'other) without any advanced electrical / electronic knowledge? If "yes" then it's worth ordering a pair just to play with on the bench.

Floating another boat ... from 'O' Level physics class of '57 I recall the Wheatstone Bridge; even an electrical pudding like me could make a circular one mounted round a central shaft. There might be a null point to get round, but it would give an input into what would normally be a traditional galvanometer but could be a totally circular dial / pointer. Any mileage in that?

Regards

Eug

[awemawson]

Eugene,

Obviously I've not seen those ones myself (as they are in Israel!) so it's not entirely clear if they share a common shaft or are on two co-axial shafts. If the later you could probably separate them and thus have your pair, but I suspect it's the former case and they are integral, in which case you'd need two.

Bear in mind that being ex avionics they will operate on the standard 400 Hz aircraft supply, but that is  pretty easy to generate.

[vtsteam]

Wow, a lot of activity while I was sleeping! Thanks for the synchro explanation, John. Very clear, and the alternator vesion seems do-able and fun at the same time. Almost tempted to try it myself even though I don't want a wind clock, just to see if it would work.

Also this morn, I started thinking that if it was a wind clock I really wanted, I'd maybe go back to the shaft and bevel gear idea. Has a lot of appeal, from just a mechanical fun perspective.

Definitely I wouldn't do the R/C servos and pots I suggested earlier. Longevity would be nil with wearing parts like pots in servos, etc. This thing has to handle variable wind direction 24/7 365/yr and, say, 20 years to be worthwhile. Or even 100, if you really want to be proud of it.

I probably wouldn't want to consume power with a wind operable device anyway!

[John Hill]

I would like someone to try the alternator idea as I am far from convinced it would work in practice!  Too many poles on the stator and too many on the rotor. 

However the rotor is easy to modify with an angle grinder just cutting the unwanted pole fingers off.  The stator would be harder but not impossible but would require a isolating each pole winding and rewiring them in groups for each third of the total.

(I have almost convinced myself to go down to the car wreckers!)

Shafts and bevel gears are not so bad but it might be easier to have cables and pulleys to do the job!  You would need a two throw crank (90 degree displaced crank pins) at each end at each end.


There is also that knobbly plastic 'chain' they use for controlling window blinds etc.

BTW, if you are going to buy a pair of  magslip/selsyn/synchro at your local surplus store make sure you are getting the right ones!  There are six or eight varieties,  various voltages, various frequencies (50,60 and 400Hz at least).  Some of them dont even rotate full circle and others will not have enough torque to pull the skin off your Milo.

[John Hill]

vsteam, if you are going to make the wind clock to be proud of you also need a wind speed indicator and I can think of no better project for the Madmodders among us than a water bucket type of pressure tube anemometer.  Just Google 'Dines pressure tube anemometer'!

The simple ones had a air inlet on the wind vane facing into wind and the air pressure was taken away via a tube to the display which was a glass tube part filled with some liquid.  Increasing wind pushed the liquid up and was read against an adjacent scale.  Madmodders should make the water bucket type where a 'bucket' was suspended by a spring over a container of water, the air pressure tube came through the container to end above the level of the water and inside the bucket, as the wind increased there was higher pressure in the bucket which rose accordingly.  The 'professional' ones made by Munro et al had a chain connected to the bucket which went around a sprocket on one of our selsyns/magslip/synchros and hence could be read remotely.  They also had a paper drum recorder for a permanent record of the wind speed and direction.

[hermetic]

KISS! use a long speedometer cable!
Phil.

[John Hill]

A speedo cable is not too silly an idea but if it get turned backwards it might jam up, but maybe that would be after several years!

[Eugene]

John, lads,

My reasons for blowing out the mechanical route are access and water tightness ..... The chimney breast where I'd site it is 3' thick of 200 year old brick and rubble. It's outside face (flush with the wall) is right into the prevailing wind and more significantly in Wales, rain. I've had the wall skinned with a waterproof membrane because of penetrating damp so I'm not going to drill any holes in it even if I had a 3' masonry bit.

Ideally I'd prefer something like the wireless weather stations that are available and convert the readout to analogue. Second best are the Israeli synchos and third would any other electrical solution that only required a small amount of cabling; I can hide that under the gable soffits outside and the roof beams inside.

Still pondering.

Eug

[mattinker]

Horrible Hi-tech solution, web cam following a flag with a screen inside!! How about instead of drilling a hole in the side of the chimney,  a weather vane on top of the chimney, with a shaft coming straight down to a bevel gear?

Regards, Matthew.

[awemawson]

A series of Pitot tubes arranged in an array radiating out from the chimney round the full 360 degrees. As many as you see fit, but perhaps N, NNE, NE etc. Bring the tubes down in a bundle and then arrange them in a suitable display array down stairs

http://en.wikipedia.org/wiki/Pitot_tube

Not only would you have a wind direction reading, but also a velocity reading 

[John Hill]

I got an old alternator today and pulled it apart,  unfortunately the stator is wound for several poles and re winding for just two poles probably puts that idea out of the park,  unless someone is very keen!


Wireless sounds good but I find ours a real pain as the batteries always fail during the worst weather of the year and it usually takes somes messing around to connect to the indoor device which maybe because of other devices in the area using the same channel.  Otherwise wireless is good especially if you can open the battery box and wire in a couple of 'D' cells for long life,  even better if it is a solar powered system.

The second of BillTodd's pictures shows the easiest to wire as it takes just two wires but there is some careful mechanical work to make a head unit that will both work and tolerate outdoor conditions plus it needs some custom electronics at the display end.   

There used to be a system available (from Australia I think) that was a wind rotor with a little tab, or sail really,  on one cup and a single magnetic pickup and just two wires indoors.  The way it worked was there were several points in each revolution where the pickup was triggered and the electronics could measure speed by counting the frequency of the signals and direction by analysing the frequency modulation which was the result of the sail on one cup.  Custom electronics and complex (for me) software.

Nothing really simple there so I have invented another!

Imagine a  transparent disk with binary codes painted around the edge, this disk is connected to the wind direction vane.

Another disk, this one non transparent, is connected to and rotates with the wind speed rotor.  There is a slot in this disk which corresponds with the painted codes around the wind direction disk.

A light is arranged to shine on a photo cell so that as the wind speed disk rotates light passes through the slot and on to the photo cell.

Electronics decode the binary code for wind direction and read wind speed from the interval between codes being received.

For the non electronic version have the signal from the photo cell connected to a loud speaker and paint the codes on the disk in Morse Code!  Only two wires required!