novel rain predicter

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rolsen

Member
does any know how those mantleshelf weather huts worked. A little man came out in raincoat if rain coming or a girl dressed for sunny day emerged if fine.

Also what were they called - i've googled with no luck.

I'm wondering if principle could be applied to novel picaxe weather device.
 
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westaust55

Moderator
A weather indicator or hygroscope was the device.

The active mechanism was typicallly twisted cat gut that "moved" as the humidity changed. I recall my parents had a clock back in the 1960's that incorporated one of these weather indicators.
It had a knob at the top of the cat gut so you could rotate the end of the "sensor" to occasionally adjust/calibrate it to match what was happening in reality.

Maybe a barometric or RH sensor thru a PICAXE to a servo operating a disk with the appripriately attired figures on the disk would be the modern equivalent.

EDIT:
you may want to read from this book on Google books (which mentions cat gut twisting with change in humidity):
http://books.google.com.au/books?id=5rALAAAAYAAJ&pg=PA132&lpg=PA132&dq=hygrometer+"cat+gut"&source=web&ots=du1qXwg-1K&sig=cp3Wfh8xDuUBbIrl-09JalVmA6s&hl=en&sa=X&oi=book_result&resnum=5&ct=result
 

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moxhamj

New Member
There are commercial humidity sensors available, so this could be an excellent picaxe project. You could even make it a retro project by making the man and the lady rotate on a servo. (Catgut works but chasing cats and stealing their insides may not be appreciated by the cat. )

It may take a bit of work to find a good price for a humidity sensor - they vary quite a bit. But this forum may come up with a good suggestion soon anyway!
 
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eclectic

Moderator
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BrendanP

Senior Member
I caught a massive feral cat in my backyard yesterday. Took 2 .22 shots to the head and one to the neck to kill it. I would of saved you its guts if I had known.......
 
hippy

hippy

Ex-Staff (retired)
I've always discounted projects using humidity sensors as being too expensive but that HCZ-J3A from Rapid is cheap enough to try and even run in a less than optimal circuit which could damage it over time ( ie, buy some spares ).

I couldn't find any example circuits for its use anywhere and at first glance it seems hard to deliver AC and be able to measure its resistance but what about building a standard RC oscillator out of CMOS 4xxx / 74xx logic ? As the humidity changes so too will its R which in turn changes the oscillator's frequency and that's easy enough to read with COUNT or PULSIN. It might even be possible to build some sort of AC oscillator / charge-discharge cycler around a PICAXE 08/08M so it only needs to be activated a few times a day which could extend its working lifetime.

At its price its got to be worthwhile someone interested in this topic ( hopefully with access to a scope ) getting a breadboard out and giving it a whirl.
 
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manuka

Senior Member
I've been an "electronic" weather watcher for decades & find displays of historic (past 24 hr) barometric pressure readings extremely useful. Any DIY design now really needs to include this, much as do ~US$50 offerings now flooding the market. It may well be worth hacking one of these?

Rainfall & humidity can be "read" in numerous classic ways - dog bowl overflowed, the old creaky knee joints etc- but the crucial rate of of change of barometric pressure is hard to sense other than by instruments. The traditional tapping of aneroid barometers (to ease their movements), has interesting been noted with today's electronic types- folks just can't stop themselves!

Stan (with a very low 969 hPa upon him = eye of present storm)
 
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Dippy

Moderator
With risk of potential Nesbitisation of this thread, maybe Rolsen just wants an electric Weather House (not Hut)?

This has all been covered and discussed and a little searching by Rolsen, or others on his behalf, will produce some info.

Weather stations are not novel and have been done many times over the years. I seem to remember Jeremy Leach spent a lot of time on his project. We haven't seen him recently, I am worried he has used too much sticky tape on a project and we'll find him bonded to a church weather cock.

Anyway, as the first post was just a vague floater* I hope this doesn't reach pointless Nesbit proportions without some effort and input from the thread starter.

*I do realise that 'floater' has another meaning :)
 
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Dippy

Moderator
That looks good. Maybe attach it to a potentiometer by means of a complicated system of string and cheap pulleys from Ebay and ADC the changes.
 
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Mycroft2152

Senior Member
Catgut is no longer used, Nylon is now the choice for many mechanical humidity indcators.

Nylon changes dimensions (length) with changes in humitity. It's pretty significant.

Myc

former textile chemist
 
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moxhamj

New Member
And catgut isn't used in sutures, though older surgeons still refer to them as such.

Good suggestion Mycroft. I also like the old "weather rock" http://en.wikipedia.org/wiki/Weather_Rock

And to the original poster, yes, this would be a perfect picaxe project. Not too hard. Lots of help here if things go wrong. And a (sort of) useful project at the end. Though not nearly as versatile as a weather rock...

And further on down the track, you could cheat, and use a picaxe to link to a wireless system and talk to a PC (or directly via a router), and ftp into your local weather bureau and get the forecast. All the bits of such a project have been published on the forum in the past. Then the little man could come out of his house with a tiny LCD sign that says "rain in 47mins".
 
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boriz

Senior Member
Anyone watch a TV series in UK called Rough Science?

One of the challenges was to predict the weather. They built a humidity sensor using a single strand of human hair connected to a lever. The lever was pivoted close to the hair (to magnify it’s swing) and the other end, weighed down by gravity, pointed to the scale. It worked (a bit). A simple electronic amplification system could be employed to make a human-hair humidity meter practical. With a slow averaging/stabilising system, it would never need re-calibration and any increase/decrease in humidity over, say, a few hours, could easily be indicated.

How about a hair + lever + ‘shade’ partially obscuring an LDR from an LED? Could work.
 
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BrendanP

Senior Member
Like Rambo said "he drew first blood not me!" that cat killed our pet ducks. I think my battery charger woes are getting to me....
 
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westaust55

Moderator
*I do realise that 'floater' has another meaning
Click to expand...
isn't that when the pie . . . . I mean weather house indicates there has been very deep soup . . . I mean rain/floods. :D



When you use a hair instead of catgut it is typically called a Hair Hygrometer (funnily enough :rolleyes:) - there is another special name a particular type of hair hygrometer but it alludes memory recall at this moment.



and with respect to the weather rock and the last line
"If rock is gone, there is a tornado (Run!!)"


The Aussie version last line reads along the lines
"If rock is gone, then some bugger has stolen it!"
 
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Jeremy Leach

Senior Member
(Yes Dippy, it's taken a year to wriggle from the sticky tape !! Beaniebots must have got even more wrapped up !)

As it's just a fun thing and no great accuracy required, I think Hippy's suggestion of variable capacitance might work - might be really simple, cheap and effective. Worth a try. Aluminium foil at the ready ...
 
premelec

premelec

Senior Member
FWIW it used to be that long BLONDE hair was the best for humidity indicators - and obtaining it could be a conversation starter... :)
 
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inglewoodpete

Senior Member
Jeremy, Great to see you're back on deck. I've missed your Friday mathematical gems for PICAXEs.

Back to the hair. In Grade 7 (yes, in the '60s) our class made a hair hygrometer. Quite successful. I still remember the squawk from the girl with long red hair that donated a strand to science.
 
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rolsen

Member
weather indicator

Thanks to everyone for both informative and entertaining replys. I knew that "everyone talks about the weather" this thread no exception.

I did finally find a design using a violin E string, that ran across and down spools, around a pointer hub to a weight. Music shop informed me that violin strings these days are steel as the old strings detuned with weather, (as luck would have it) I got one cheap that had been in stock many years.

Now to join it to the picaxe!!!!
 
R

rolsen

Member
more on novel weather indicator

I must apologise for inadvertent attachment on previous reply.



Quote "Anyway, as the first post was just a vague floater* I hope this doesn't reach pointless Nesbit proportions without some effort and input from the thread starter."

Dippy, I have noted suggestions and will begin this project and advise outcome. One other wetting effect i've noticed in nature involved "wild oat seed" this seed has two " bent legs" which turn if the seed gets wet. Again thanks for many helpful suggestions.
 
lbenson

lbenson

Senior Member
At that price, about $.60US, I'd love to find some to play with. But the site has no information about the manufacturer of the product, so I don't know what to look for to find a seller with reasonable shipping to the U.S.
 
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papaof2

Senior Member
Note that the humidity sensor requires AC - 1v rms at 1KHz - and that you can NOT apply DC to it.

Measuring impedance instead of resistance will be a little more complicated :-(

John
 
hippy

hippy

Ex-Staff (retired)
In post #11 of this thread I suggested a way it might be done. It would probably be worthwhile someone interested in humidity giving it a try.
 
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westaust55

Moderator
Quote "Anyway, as the first post was just a vague floater* I hope this doesn't reach pointless Nesbit proportions without some effort and input from the thread starter."

Definition of a Fairy Tale:
A story about something that didn't happen long ago
 
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Jeremy Leach

Senior Member
Another idea, which could be cheap but maybe not too practical (?!), is to measure humidity using the wet and dry 'bulb' principle. e.g ...

http://support.radioshack.com/support_tutorials/weather/weather-18.htm

Could have two DS18B20s, one covered in cotton etc with a wick into some water. Then 'all' you need is some code to decipher the difference in temperature readings ! Unless there is moving air it won't be that accurate - but this thing isn't meant to be.

I'm only half joking on this, but it might actually be the cheapest method of getting rough humidity ....??

Cue jokes about adding a complex alarm system to remind about topping up wet bulb reservoir ...
 
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