Gina

For goodness sake use eye protection when working with glass!! Your eyes are your most important asset - anything else is irrelevant. Astronomy is useless if you damage your eyes. ALSO - seek immediate medical attention if you get glass in an eye, it can do irreparable damage!! And plese tell me you're alright - PLEASE.

I've been thinking about all this even though this project is on hold. The previous circuit using obsolete 1-wire chips is AFAIK still in working order. I shall need to do some tests to make sure but if it works is seems to make sense to use it now that the DS2408 method has ground to a halt. Yes, I've changed my mind There will be a couple of differences - the anemometer uses a hall effect device instead of a reed switch and the optical sensors for the wind vane will be using proper reflective optical sensors with IR LED and phototransistor in the same casing rather than separate components. These will most likely produce a difference in the phototransistor on/off currents so different value resistors will be wanted to convert these currents to voltages.

Yes and yes... I'm using the Dallas OneWire library but the DS2408 library doesn't seem to work. I'm probably missing something.

I've been straining my brain trying to work out how to control the DS2408 1-wire device. There is an Arduino library but I can't get it to work. So I've been trying to use the OneWire library alone to directly communicate with this device but without much luck so far. I've scoured the web for info and there seems to be very little out there - even the Arduino forum hasn't solved the issue. I've also posted in a weather forum where 1-wire is pretty popular but no joy. The makers of these chips, Maxim, have discontinued several almost essential 1-wire devices and have provided no alternative. The DS2408 is an 8 bit programmable input/output device with strobe which could take over in conjunction with standard CMOS logic or even microprocessor. My question is - does anyone here have any knowledge of controlling the DS2408 or indeed more knowledge than me about the Maxim 1-wire device control in general? I'd be most grateful for any help - I'm on the point of giving up and that's not like me.

Tried that but it wasn't successful even though I used slow setting epoxy to help avoid contraction and breaking the gold wires. I'm using a 3D printed shield to protect the wires now and that seems to work well. No broken wires

Thank you Jan

Looking at a purely digital alternative to the diode pump circuit and DS2438 A/D converter, I'll consider a CMOS counter and DS2408 8 bit PIO device. Pulse rates from the anemometer can vary from a pulse every couple of seconds up to 64 pps for winds of 64mph (near hurricane force). Now the Met Ofice measure wind speed over a 3s interval and I think I'll do the same so that's a range of 1 to around 200 counts. So 8 bits of data (256 levels) would be fine. So one way of dealing with the anemometer would be to use an 8 bit CMOS counter and read the data with a DS2408. This could be a viable option once I've sorted out how to use the DS2408 For the counter the CMOS 4000 range, dual 4 bit counters - 4520 looks suitable. Datasheet for MC14520B (one make)

I'm going to look into using a diode pump circuit plus DS2438 to read the wind speed. The diode pump circuit converts the pulse rate from the anemometer to an analogue voltage and the DS2438 will read this and convert it back to digital. This sounds a bit daft but with Maxim no longer producing any form of 1-wire counter device it's either that or measure the period of the pulses which would require very fast sampling to read high wind speeds. We 1-wire weather afficionados are very cross at Maxim drawing the mat from under our feet!! The 1-wire device I was going to use to read the wind direction has also been discontinued This is another part that will need a complete rethink. My original idea was to use optical sensors and a Gray encoded disc to convert the wind vane angle to 16 discrete digital values. With the optical sensors using photo-transistors with an analogue output and no hysteresis the system is very sensitive to noise if a simple logic device were used to detect the light level. I was using a DS2450 quad A/D converter where each photo-transistor would be read as an analogue current and hysteresis applied in program code. With the DS2450 chip being obsolete I shall need to rethink how I shall read the wind direction. One solution would be to use a CMOS Schmitt trigger chip on the photo-transistor output and then read the digital data using something like a DS2408 8 bit PIO chip. I'm currently investigating how these can be controlled from the Arduino 1-wire system.

I'm going to continue posting ideas for the circuitry to read the wind instruments here. The main issue is Maxim discontinuing several 1-wire devices that I was using for the weather station and not providing any replacements. Yes, ideas as opposed to definite designs and that's why I would prefer not to clog up the Instrumentation thread in the DIY Observatories forum. I could conrtinue to use the components as already designed but these are two of the discontinued ones with no replacements available. I never like to design anything when I have only one of any component in case this should fail. I think it makes more sense to redesign the circuit to use only currently available components and buy at least two of these for spares. If an obselete component failed I would then have to redesign and rebuild the assembly maybe involving more than just a change of circuit. Better to start with the new design I think.

Much of this project has been taken over by my Observatory Environment Instrumentation thread in the DIY Obsvertories forum, as I will be reading temperature and humidity outside near the observatory and inside in both scope room and warm room plus the water level in the hole underneath. Wind speed and direction are also highly relevant to the observatory (as is rainfall) as I have experienced many times over the years and particularly in the last couple of months! So discussion of the weather instruments will mostly be covered in the observatory thread and this thread will deal more with data processing and upload to web site. That will be after I get the instrumentation and communication aspects sorted out and display of the data by dials on the living room wall next to my moon phase clock.

Doesn't look like I'll be testing tonight - clouds are back

Been taking my gear back out to the observatory but realised I need to sort a few things out before I can test the debayered camera attached to the EQ8 mount, so I think I may get set up with an Atik camera and check that I can get things to work after goodness knows how many months since last time. The power system is set up for use with the MN190 ATM and will need a new box for connecting the 450D. The current box is attached to the MN190 dovetail bar. If I can find the right adapters I should be able to hang the 450D off the MN190 for first tests (that's f5 which is much the same as the tele-zoom lens). This scope is equipped with OAG and guide camera so guiding should work. This will mean I can try longer exposures without worrying about eliptical stars (though if the polar alignment is good enough it might not be necessary with this size image sensor). Exposure length will be determined by noise as I haven't arranged cooling yet. Mind you the ambient temperature won't be much above freezing The filters are 1.25" so may get some vignetting - I have Baader 36mm filters for the "proper job" with DSLRs.

Very interesting Herra Now that is really brutal I'm going for Canon EOS 450Ds for debayering but may attempt 1100Ds again later. The cover glass on the 450D can be removed without heat with a craft knife worked carefully round the joint I haven't had quite as much success removing the CFA though and produced some damage on the two sensors I have worked on recently. I hope to be testing these with a Baader Ha filter mounted on my EQ8. Tries with the NEQ6 indoors through a window were unsuccessful as the mount wasn't polar aligned - the EQ8 is. I'm hoping the ground is firm enough to get out to the observatory tonight or whenever we get a few hours of clear night sky. Orion is in a favourable position to try this on M42

I was going to put the main weather station unit in the observatory since that is where most of the data comes from but communicating the data to indoors has turned out to be more difficult than I had thought. Now most of the sensors are 1-wire and this is a multi-device bus with a range of up to 100m and well capable of reading weather sensors from the house so it makes more sense to me to locate the main unit indoors where it acn be connected by USB to a computer for weather data processing and uploading to my weather website. The Arduino can control the display dials on the living room wall and if the UNO hasn't got enough data pins, I can use a Mega which is also compatible with the data logging shield. The sensors which aren't 1-wire are the DHT22 Digital Humidity and Temperature sensors and the unit which measures sky cloud and whether it's raining. The latter uses an Arduino and I could probably use the same Arduino to connect to the DHT22s. It then remains to arrange a way of connecting the Arduino as a slave on the 1-wire bus to collect the data. I have a method for the water level data but that only applies to one data value which changes very slowly. The weather data is another matter though reduced by moving the i-wire sensors directly onto the 1-wire bus

I've been giving some thought to the sensor system for the anemometer. Currently the idea is a magnet on the rotor and reed switch underneath in the fixed part. This gives two closures per revolution as the reed switch closes with either N-S or S-N magnetic field. With one revolution per second estimated to represent 3mph this means a pulse per second for each 1.5mph. So the wind speed reading is only resolved to 1.5mph if a period of 1s is used for counting. I wonder if 1.5s would be short enough to detect gusts - that would give a 1mph resolution. Average speed could have a much higher resolution by using a longer counting period. Maybe I'll ask this question in a weather forum. Another thing I noticed with magnetic sensing is that the anemometer rotor tends to "lock on" to the positions at either end of the reed switch due to magnetic attraction. This reduces the wind speed at which the anemometer starts to turn so I might change over to optical sensing. Also, I've heard of reed switches failing in this application with millions of operations a week. Optical sensors have no such problem. Optical sensing could use a multi-slot disc on the rotor and give faster and more accurate wind speed readings.

One part that wants replacing with a 3D printed plastic part is the mounting of the vane shaft and damping magnet to the ball bearing the vane pivots on.

Here are a couple of photos of the latest anemometer.

Nice clever design

Very nice image and thank you for the suggestion And yes, I've thought of the problem of getting 3 zoom lenses to the same FL but it's not too critical - the software takes care of it and I'll just crop to the smallest image of the three. I've finished bidding for cameras now

Well it looks like I can debayer the 450D sensor adequately but I see no point in proceeding any further until we get something I can test it on so I'm going back to my other projects. In the meantime it's quite likely that my Baader 36mm unmounted OIII filter will turn up. And having pretty much sussed out debayering the 450D I may think about a triple imaging system using 3 cameras. I have bid for and won a 75-300mm Canon zoom lens so that (x3) could provide the optics. I shall have to work out which DSOs the APS-C sensor and this range of focal lengths will accommodate. I know a zoom lens is not ideal for AP but I can't find any prime lenses at a reasonable price. Of course, two more SW Esprit scopes to go with the one I have already would be ideal but too expensive The advantage of a triple rig, apart from triple light gathering, is that I wouldn't have to accommodate a filter wheel and a Canon lens can be attached directly to the mount, preserving optical alignment. As can a telescope, of course. As for the OIII filter and debayering, I think it's dubious that debayering would give much advantage in a triple imaging rig. I know it will use only 3 of the 4 pixels in the quad and that sensitivity is reduced by being off-peak but the microlenses should make up for that and the sensor will effectively be binned 2x2 (almost). The Ha should give the resolution. But all this is up for experimentation later On a general point - I'm finding it very difficult to generate any interest in astro projects with the continuing dull, dreary, damp and depressing weather and the nil prospect of any astro imaging in the foreseeable future

Actually, I'm thinking all of this is a waste of time and money unless and until we get some clear night skies!!! It doesn't look like that will happen this year

I couldn't get the scraping method to work. The scraper was either too soft and wouldn't touch the CFA or too hard and made deep scratches. Polishing seems to leave the sensor clean and pretty flat. I think flats will take care of the remaining variation. Cover glasses seem to come off 450Ds without any problem and the CFA seems softer. I don't think I'll be able to tell how well my debayered 450D sensors work until we get some clear night skies and I can try on some DSOs. My MN190 is all set up and ready to go in the obsy - it would just be a matter of swapping cameras. I expect to get back to 1100Ds shortly but want to see how well 450Ds do first.

I wouldn't think so. But I haven't tried it. I don't even know if it could be got to fit.

Yes! It works - I can remove the microlenses and CFA without causing any lines, hot pixels or scratcges

Going through all my debayering stuff I've come across three 450D sensors. Two are totally duff but the other is fine and has already had the cover glass removed. So another candidate for debayering I'm going to see if this sensor will succumb to the fine abrasive regarding microlenses and CFA. Meanwhile, I've fitted it into my test camera and run a 10m dark. As before, I used the maximum ISO of 1600. Image stretched extensively to show the noise. No bright dot at the bottom on this image and noise seems pretty constant across the frame